CLASS NOTES - SMALL ANIMAL THERIOGENOLOGY
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CANINE - FEMALE
Anatomy
- Ovaries - Not routinely palpable or visible by ultrasound in normal bitches
- Uterine tubes
- Uterus - Bicornuate - Not routinely palpable or visible by ultrasound in
normal non-pregnant bitches
- Cervix - Abdominal - Tightly closed except during estrus, the peripartum
period, or in the presence of uterine disease
- Vagina - Extremely long - The dorsal median postcervical fold obscures the
external cervical os. Formed from the paramesonephric (Mullerian) ducts
- Vestibule - Forms junction with the vagina just cranial to the urethral
papilla - Forms from the urogenital sinus - The ventral portion is the clitoral
fossa.
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Techniques
- Vaginal cytology
Vaginal epithelial cells mature to keratinized squamous epithelium under the
influence of estrogen. Estrogen concentrations rise through proestrus and
peak just prior to the onset of standing heat. Cornification (=keratinization)
of the vaginal epithelium develops gradually, paralleling estrogen concentrations.
You can interpret the population of vaginal epithelial cells, WBCs and bacteria
collected on a swab of the dorsal vaginal surface during the estrous cycle
to try to predict reproductive events, and can do vaginal cytology at any
time to assess for reproductive tract pathology and as a bioassay for estrogen.
Technique - Moisten a cotton-tipped swab with water or saline (this is not
a sterile procedure). You may use a standard length swab since changes in
cytology are the same throughout the vagina. Insert at the dorsal commissure
of the vulva, advance craniodorsally till the swab goes over the ischial arch,
then advance cranially. Roll the swab against the dorsal vaginal surface,
pull it straight out, roll onto a glass slide, allow to air dry, and stain
with new methylene blue or DiffQuik.
Interpretation - Four cell types exist. Parabasal and intermediate cells are
the two non-cornified cell types, and superficial cells and anuclear squames
are the two cornified cell types. There is a gradual increase in percent cornification
as the dog progresses from proestrus to estrus, and a abrupt return to complete
non-cornification at the onset of diestrus. Swabs from early proestrus and
diestrus look exactly alike.
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- Vaginal culture
Direct uterine culture is only possible via laparotomy with hysterotomy. The
vulvar discharge present during proestrus and estrus originates in the uterus,
so indirect uterine culture can be performed by anterior vaginal culture during
proestrus or estrus. Use a long guarded culture instrument. Insert as for
collection of a vaginal cytology specimen. Be aware that there is a large
population of normal flora present in the vagina.
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- Vaginoscopy
Instruments used = vaginoscope, endoscope, otoscope. Insert as for collection
of a vaginal cytology specimen. Vaginoscopy allows visualization of the vaginal
mucosa, and assessment for source of discharges, presence of masses, foreign
objects, vaginal anomalies, etc. Vaginoscopy will not allow visualization
of the external cervical os.
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- Hormone assay
Estradiol - Estradiol
is not routinely measured in serum. It is present in very low concentrations
(pg/ml) and the assay sensitivity may be above this. Concentrations of serum
estradiol vary greatly even within one animal. It is generally better to use
vaginal cornification as a bioassay.
Progesterone - Progesterone can be measured by
enzyme-linked immunosorbent assay (ELISA) or radioimmunoassay (RIA). ELISA
tests can be run in-house, but the accuracy is not good. These tests are semi-quantitative;
the Premate progesterone assay (Synbiotics) gives results of low (< 3 ng/ml)
or high (> 3 ng/ml). RIAs must be sent out but the accuracy is excellent.
RIAs can be done at any commercial or hospital laboratory.
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Estrous cycle
- Puberty - Female dogs reach puberty, defined as the first observed heat,
from 6 to 24 months of age, with an average onset of 10 to 12 months of age.
Small breeds come into heat earlier than large breeds. The pubertal estrus
may be a split or false heat. You may induce an early pubertal estrus by housing
a young bitch with cycling females. Bitches cycle, on average, every 7 months.
Some breeds cycle more frequently (German Shepherd dogs and Rottweilers may
cycle as frequently as every 4.5 to 5 months) and some less frequently (Basenjis,
dingos and wolf-crosses cycle yearly).
- Stages
- Proestrus
Length = 9 days average, range 0 to 17 days
Physical changes and behavior = The vulva is
enlarged and firm. Vulvar discharge ranging in character from serous to serosanguinous
is present. Male dogs will be attracted to the bitch but she does not stand
for breeding, and often tucks her tail under tightly, sits down, or turns
on the male dog.
Endocrinology = This is the follicular stage
of the cycle. Estrogen concentrations rise during proestrus and peak at the
end of this stage. Serum progesterone and luteinizing hormone (LH) concentrations
are low.
Vaginal cytology = RBCs may be present throughout
the stage. PMNs are present early in this stage but disappear as estrus nears
and the vaginal epithelium thickens. The vaginal epithelial cell population
gradually changes from completely non-cornified to completely cornified. Cornification
will be complete about 2 days before estrogen peaks, about 4 days before standing
heat begins.
To view an image of early proestrous vaginal
cytology, click here.
To view an image of late proestrous vaginal
cytology, click here.
To view a chart detailing endocrine changes during the
estrous cycle of the dog, click here.
- Estrus
Length = 9 days average, range 3 to 21 days
Physical changes and behavior = The vulva may become
less turgid as the bitch enters standing heat. The vulvar discharge may become
straw-colored but can range from serous to serosanguinous in a normal bitch.
Estrus, or standing heat, is defined by the behavior of the bitch; standing
= remaining motionless as the male investigates her hindquarters, flagging
= deflection of the tail laterally and muscular elevation of the vulva.
Endocrinology = Estrogen concentrations fall at the beginning of estrus. This
decrease in estrogen, along with a preovulatory rise in progesterone, is necessary
for appearance of breeding behaviors in the bitch, and presumably elicits
the LH surge. A surge of LH is released from the pituitary on or about the
first day of estrus, and causes ovulation of a primary oocyte 2 days later.
Great variation in time of ovulation exists in the normal dog. After ovulation,
CLs form and progesterone production begins. Measurement of serum LH is not
routinely performed. However, measurement of serum progesterone concentrations
easily can be performed and this data used to optimize breeding management.
Vaginal cytology = The vaginal epithelial cell population is completely cornified,
with greater than 50% of the cells anuclear squames. No PMNs or debris are
present. Intra- and extracellular bacteria are commonly present. RBCs may
or may not be present. Vaginal cytology cannot be used to predict ovulation
time prospectively; however, vaginal cytology changes abruptly as the bitch
enters the next stage of the cycle, diestrus, with this change consistently
occurring 6 days after ovulation.
To view an image of estrous vaginal cytology,
click here.
- Diestrus
Length = 60 days average, range 50 to 80 days
Physical changes and behavior = There are no characteristic physical changes
or behaviors in diestrus. Small amounts of mucoid vulvar discharge may be
present. Some bitches still stand to be bred early in this stage.
Endocrinology = Bitches maintain the CL for about 60 days whether they were
bred or not at that cycle. Progesterone concentrations are high throughout.
Diestrus ends with a decline in serum progesterone to less than 2 ng/ml. This
is associated with whelping if bitch is pregnant, false pregnancy or no outward
signs if she is not. The CL is the sole source of progesterone during pregnancy
in the bitch.
Vaginal cytology = On the first day of diestrus, the vaginal epithelial cell
population abruptly shifts to complete non-cornification. There may be a large
number of PMNs present, and metestrum cells (non-cornified cells containing
leukocytes) and/or foam cells (non-cornified cells containing vacuoles) may
be present.
To view an image of diestrous vaginal
cytology, click here.
- Anestrus
Length = About 4.5 months average, so counting the approximately 2.5 months
of proestrus, estrus and diestrus, the overall interestrous interval averages
7 months. This is a period of reproductive quiescence with no characteristic
physical, behavioral or endocrinologic changes. Vaginal cytology reveals only
scant numbers of non-cornified epithelial cells at this stage.
To view an image of anestrous vaginal
cytology, click here.
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Breeding management
- Ovulation timing
- Prospective methods
* Count days from estrus onset - Poor! Great variability exists between normal
bitches.
* Progesterone assay - Progesterone begins its normal rise at the time of
the LH surge that stimulates ovulation. Serum progesterone concentrations
are about 2 ng/ml on the day of the LH surge, and 4 to 10 ng/ml on ovulation
day. Knowing this, we can measure serial serum progesterones in a dog, and
watch for the time of its rise to predict ovulation. Once progesterone begins
to rise, reaching a concentration of about 2 ng/ml, ovulation will occur in
2 days.
| Serum progesterone (ng/ml) |
Event occurring
|
|
< 1.0
|
Anestrus or proestrus |
|
1.0 - 1.9
|
Ovulation minus 3 days - Recommend recheck |
|
2.0 - 2.9
|
Ovulation minus 2 days |
|
3.0 - 3.9
|
Ovulation minus 1 day |
|
4.0 - 10.0
|
Ovulation day |
|
---
|
Optimal breeding day is 2 days after ovulation |
|
> 10.0 with cornified vaginal cytology
|
Ovulation plus 1 to 5 days |
|
> 10.0 with non-cornified vaginal cytology
|
Diestrus - Too late to breed this season |
If I do not know the history of the bitch, I usually ask to first see her
when the owner perceives her as having been in heat for 4 to 5 days. I start
with vaginal cytology and only draw blood for progesterone assay if it is
greater than 60 to 70% cornified. The earliest I have known a bitch to ovulate
was 4 days from the onset of proestrus. The latest was 32 days from the onset
of proestrus.
* Luteinizing hormone (LH) assay - Because the LH peak lasts at most one day,
blood samples must be drawn daily and at about the same time of day to increase
chance of identifying the LH surge. This is cumbersome and expensive for the
owner. One practitioners recommends freezing leftover serum from progesterone
assays and running the LH test on samples believed to be indicatve of the
LH surge, as a way to verify progesterone results without undue inconvenience
or expensive to the owner.
* Breeding history - As far as is known, most bitches will ovulate on or about
the same day of their cycle from one heat to the next.
- Retrospective methods
* Diestrous smear - The abrupt transition from the complete cornification
seen on cytology during estrus to the complete non-cornification seen in diestrus
happens 6 days after ovulation.
* Whelping history - Gestation length is 62 to 64 days from ovulation. If
good records are kept of the date of onset of heat and subsequent date of
whelping, subtraction of 63 calendar days from parturition equals date and
day of the estrous cycle when ovulation occurred.
- Breeding timing
Sperm must undergo capacitation within the female tract; this requires about
7 hours. Normal sperm can remain viable in a normal female tract for up to
7 to 9 days. The ovulated oocyte is a primary oocyte which must undergo 2
meiotic divisions before fertilization can occur. This maturation process
takes about 2 days.
Best conception rate occurs when the bitch is bred from 4 days before to 3
days after ovulation; best litter size is achieved when the bitch is bred
2 days after ovulation.
There are 2 possible breeding strategies:
* Breed every other day while the bitch stands
To view an image of normal
canine breeding behavior, click here.
* Breed once, 2 days after ovulation
To view an image of a client handout describing breeding
management, click here.
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Estrus suppression
- Ovariohysterectomy (OHE)
Advantages: Prevents conception, signs of heat, appearance of uterine disease,
confers protection against later mammary cancer if the dog is spayed before
or shortly after the first estrus.
Disadvantages: Cost, risk of anesthesia, permanent contraception, estrogen-responsive
urinary incontinence, perivulvar dermatitis and obesity may be sequelae.
- Progestogens - Progestogens exert negative feedback on the hypothalamus
and pituitary, preventing release of gonadotropins and ovulation. The only
progestogen currently approved is megestrol acetate (Ovaban - Schering). It
can be used in 2 ways:
* Anestrus - 0.25 mg/lb po x 32 days
* Proestrus - 1.0 mg/LB PO x 8 days, begun within first 3 days of cycle
Return to heat is extremely variable with a range of 2 to 9 months. Megestrol
acetate should not be given to a bitch on her first cycle or for more than
2 consecutive cycles. If used as directed, there is no adverse effect on fertility.
It is contraindicated in bitches with predisposition to progesterone-dependent
disease conditions, e.g. previous pyometra, mammary nodules, or diabetes mellitus.
- Androgens - Androgens act by exerting negative feedback on the pituitary,
preventing release of gonadotropins and ovulation.
The only androgen currently approved is mibolerone. As of August 2002, the
approved product (Cheque - Upjohn) was not available. Mibolerone has no progestational
or estrogenic effects. Treat with 30 mcg/25# BW PO SID up to 1.8 ml daily
for the length of time the dog is to kept out of heat (German Shepherd Dogs
should get 1.8 ml daily regardless of body weight). Mibolerone must be started
at least 30 days before the next estrus is due to begin. Return to estrus
after the drug is withdrawn is variable, with an average of 70 to 90 days
(range 7 to 240 days). This drug is not recommended for use in the pubertal
heat, or for use in breeding bitches. No adverse effects on fertility have
been reported. The drug is contraindicated in Bedlington terriers, bitches
with androgen-dependent disease (e.g. perianal adenomas), or those with renal
or hepatic dysfunction. Side-effects include clitoral hypertrophy and vaginitis.
Testosterone often is used to suppress estrus
in racing Greyhounds. While under racing stress, low doses (5 mg testosterone
per os daily or 50 mg injectable testosterone esters monthly) suppress heat
in the bitch.
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Pregnancy termination
In general, methods that terminate pregnancy
prior to day 40 of gestation result in absorption of fetuses while those after
day 40 result in expulsion of fluid or tissues. Puppies passed after about day
55 of pregnancy may be alive and should be euthanized when passed.
- OHE
Method: Physically remove the gravid uterus and both ovaries
Pros: 100% effective, protection against future mammary neoplasia, ovarian
and uterine disease
Cons: Surgical and anesthetic risk, cost, permanent contraception, post-surgical
complications
- Estrogen ("mismate" shot)
Method: Estrogen slows movement of ova through the uterine tube, causes degeneration
of ova, and alters the endometrium, affecting implantation
Pros: Low cost, effective if given mid-estrus to early diestrus (post-ovulation)
Cons: May induce pyometra, ovarian cystic disease and/or pancytopenia, ineffective
if given at wrong stage of cycle, prolongs standing heat
- Prostaglandin (PGF-2a, Lutalyse)
Method: PGF-2a causes lysis of the CL with a subsequent
decline in serum progesterone concentrations, and causes uterine contractions.
Pros: Effective at all stages of gestation after the fifth day of diestrus
(250 mcg/kg SQ BID x 4 days), fertility unaffected
Cons: High cost, side-effects of hypersalivation, emesis and defecation, may
cause early return to estrus. The GI side-effects may be minimized by concurrent
administration of atropine (0.025 mg/kg SQ).
- Dexamethasone
Method: Mimics normal decrease in progesterone induced at time of whelping
(see Endocrine induction of parturition)
Pros: Effective after day 30 to 35 of pregnancy, can be given orally so dog
need not be hospitalized (0.2 mg/kg BID x 10 days). Abuse potential minimal.
Cons: Short-term side-effects include PU/PD and vulvar discharge.
- Miscellaneous
* Mifepristone (RU 486) - Blocks progesterone receptors
* Prolactin inhibitors - Bromocriptine (Parlodel - human product) or cabergoline
(Dostinex - veterinary product)
* Combination therapy can be used, such as bromocriptine and prostaglandin
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Pregnancy
- General information
Fertilization occurs in the oviduct. The embryo enters the uterus as a morula
day 8 to 12, and implantation occurs day 17 to 18. Dogs form an endotheliochorial
zonary placenta with marginal hematomas containing the green pigment uteroverdin.
Gestation length = 62 to 64 days from ovulation. Due to variability in the
time of ovulation compared to time of standing behavior in the bitch and the
long time sperm are viable in the female reproductive tract, gestation length
from a single breeding can range from 58 (bred late) to 71 days (bred early).
Pregnancy endocrinology - Progesterone must be present to maintain pregnancy.
All progesterone is produced by the CL in dogs. No pregnancy specific gonadotropins
are released.
- Pregnancy diagnosis - This is confounded by the fact that all bitches maintain
the CL and undergo a prolonged luteal phase. Endocrinologic tests and assessment
of physical changes are unreliable.
* Palpation - Abdominal palpation should be performed from 28 to 35 days after
ovulation. Accuracy is poor in a tense or obese animal.
* Radiography - Less than 42 days from ovulation you can visualize an enlarged
uterus but cannot differentiate pregnancy from uterine disease. You can first
see calcification days 42 to 45 from ovulation (variable number of days from
breeding). Late in gestation, radiography is the best predictor of fetal number,
and can be used to estimate fetal age and to assess for fetal death.
To view a chart showing correlation of fetal mineralization
with gestational age, click here.
Signs of fetal death include gas within or around fetus, collapse of the axial
skeleton, overlap of cranial bones and/or failure of skeleton to calcify or
fetus to grow; lack of signs of fetal death does not imply viability.
* Ultrasound - Fetal vesicles are first visible routinely day 24 to 28, and
fetal heartbeats are easily visible after day 30. Fetal heart rate and movement
can be used to assess fetal viability.
To view an image of mid-gestation
pregnancy on ultrasound, click here.
* Relaxin - A commercial assay is available (Witness - Synbiotics). Accuracy
is good after about 28 days of gestation.
* Miscellaneous - Acute phase proteins (fibrinogen), measurement of serum
prolactin after challenge with naloxone
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Parturition / Dystocia
- Endocrine induction of parturition
The fetus induces parturition. The hypothesized scheme is : Fetal ACTH causes
release of fetal and maternal cortisol with subsequent decrease in progesterone
secretion and increase in production and release of estrogen and prostaglandin.
Dead or abnormal fetuses, or small litter size, may be insufficient to initiate
labor.
Progesterone is thermogenic. As the serum progesterone concentration declines
at the time of parturition, you will see a transient decrease in body temperature
until other thermoregulatory systems take over. Most bitches begin labor within
24 hours of a rectal temperature drop to less than 99 degrees F.
- Normal parturition
* Stage I = cervical dilation. This occurs secondary to increased estrogen
and prostaglandins, and decreased progesterone, uterine contractions and the
pressure of the fetus at the cervix. Contractions are not visible. The bitch
is restless, pants and may vomit. Signs should increase in frequency and severity.
* Stage II = expulsion of fetuses. The cervix should be fully dilated. The
length of this stage is variable, 6 to 12 hours on average. Abdominal contractions
are strong and coordinated. The chorioallantoic sac may be seen first, then
the pup with or without the covering of the amniotic sac. Puppies may present
cranially or caudally. You ordinarily see passage of a neonate every 30 to
60 minutes. You should see passing of the first pup within 4 hours of labor
onset, and the bitch should deliver pups at least every 2 hours thereafter.
The bitch should tear away the amniotic sac and lick the neonate to stimulate
respiration. If the bitch ignores the pup, tear away the sac and rub briskly
with a towel. You may need to aspirate fluid from the pup's respiratory tract.
* Stage III = expulsion of placentas. Placentas usually pass 5 to 15 minutes
after each pup is born. The bitch may eat them; they have no known physiological
value, and may cause vomiting and diarrhea.
- Post-partum period
* Uterine involution
Normal uterine involution takes 4 to 5 weeks. Administration of oxytocin to
promote uterine contraction post-partum is only necessary if the pups are
stillborn or not nursing.
* Lochia
Lochia = normal vaginal discharge present for up to 3 weeks after whelping.
Lochia should be sero-mucoid and odorless, ranging in color from pale brown
to pale green. Lochia may be slightly hemorrhagic.
* Rectal temperature
Slight elevation in body temperature is normal for the several days following
parturition.
* Care of the neonates
Warmth - Leave with bitch or provide an external
heat source. Pups are incapable of thermoregulation until 2 to 3 weeks of
age. Be careful with heating pads or heating lamps; pups are easily burned.
Colostrum - All pups should nurse within the
first 12 hours of life. Pups receive 75 to 80% of maternally derived antibodies
from colostrum.
Weight - The pups should double their birth
weight by 10 to 14 days of age.
Tails and dewclaws
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- Dystocia
"dys" = difficult, "tokos" = birth
- Causes
Maternal
* Obstruction
of passage
-
Pelvis - congenital or acquired
-
Vagina - hypertrophy, neoplasia, developmental
-
Vulva - "infantile"
* Abnormality
of uterine function
-
Obese, debilitated, poorly exercised
-
Primary inertia = no second stage of labor seen, requires C-section
-
Secondary inertia = second stage starts but does not progress as uterine muscle
fatigues. May be obstructive so be cautious with ecbolic agents.
* Abnormality
of pregnancy
-
Fetal fluid disorder
-
Herniation or torsion of uterus
Fetal
* Obstruction
of passage
-
Relative oversize = birth canal too small
-
Absolute oversize = pup too big, birth canal normal
* Developmental
abnormality
-
e.g. fetal monster, hydrocephalus
* Abnormal presentation,
position, posture
-
Presentation = relation of long axis of pup to birth canal. Cranial and caudal
are normal.
-
Position = relation of fetal vertebral column to birth canal
-
Posture = disposition of head and limbs
- Determination of dystocia
Questions to ask:
* Obvious malpresentation?
* First stage > 12 hours, second stage weak and intermittent > 2 to
3 hours, second stage hard > 30 minutes, > 2 hours between pups?
* Abnormal vulvar discharge? Pus, frank hemorrhage, green fluid (denotes placental
separation)
* Rectal temperature decline > 24 hours ago?
* Signs of labor not progressing?
* Systemic illness in bitch?
* Prolonged gestation?
* High risk pregnancy? (Previous pelvic trauma or dystocia)
Presentation:
* History
- Previous disease or trauma
- Breeding dates
- History of previous whelpings
- Pups and progress at this whelping
- Temperature drop data
- Treatment thus far
* Physical examination
- General examination
- Abdominal palpation
- Digital vaginal examination
- Lateral abdominal radiographs
- Uterine monitors (WhelpWise)
Treatment of dystocia
Manipulative
* Feathering
* Digital manipulation
* Instruments
Pharmacologic agents
* Oxytocin - Oxytocin
acts as an ecbolic (causes uterine contraction). It may cause premature placental
separation and should not be used in obstructive dystocia. Dose = 2 to 5 IU
at 20 to 30 minute intervals, for no more than 3 to 4 doses if not effective.
* Calcium
* Glucose
Cesarean section - Anesthesia
for C-section
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Abnormalities of...
- Puerperium
I will only discuss eclampsia at this point but be aware that metritis, mastitis,
and subinvolution of placental sites are also puerperal conditions.
- Eclampsia
= Puerperal tetany = hypocalcemia. This is seen primarily in small breed dogs
nursing large litters during the first 2 to 4 weeks of lactation, when the
bitch is under the heaviest metabolic stress due to lactation. It may also
be seen at or near parturition.
Serum calcium concentrations fall to about 4 to 7 mg/dl (normal 9 to 11 mg/dl).
The initial presentation is trembling and weakness. As the condition progresses,
dilation of the pupils, elevated pulse rate, elevated body temperature and
eventually convulsions occur.
Treatment includes removal of pups from the bitch for 12 to 24 hours, administration
of 5 to 10 ml 10% calcium gluconate solution slowly IV while ausculting the
heart (give to effect - too rapid infusion can cause bradycardia, cardiac
arrhythmias and/or cardiac arrest). Follow-up therapy includes administration
of 5 to 10 ml 10% calcium gluconate SQ, and discharge of the dog with 1 -
3 gm calcium lactate or calcium gluconate to be given PO SID with 10,000 to
25,000 IU Vit D. Oral calcium gels also exist. Recurrence in the same or a
subsequent lactation is common. Wean pups only if more than one clinical episode
occurs within a lactation.
Some people feel that post-parturient hysteria (savaging of pups) may be a
manifestation of eclampsia. Insure the bitch is on a well-balanced ration.
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- Metritis (see Uterine disorders)
- Mastitis (see Mammary gland disorders)
- Subinvolution of placental sites (SIPS)(see Uterine disorders)
- Cysts
Bitches present with a history of irregular cycles or, more commonly, with
a history of prolonged proestrus and/or estrus. Ascertain whether the bitch
is truly in a prolonged heat cycle. You may need to perform serial vaginal
cytology and progesterone assays over 2 to 3 weeks to verify this.
Diagnosis is based on a true history of persistent estrus, and physical examination
and vaginal cytology signs indicative of estrogen secretion (swollen vulva,
cornified vaginal epithelial cells). Similar signs may occur secondary to
functional ovarian tumors. Differentiate by abdominal palpation, abdominal
radiography or ultrasound, exploratory laparotomy, and response to treatment.
Treat with induction of ovulation using gonadotropin releasing hormone (GnRH;
50 mcg IM) or human chorionic gonadotropin (hCG; 1000 IU, half IV, half IM).
The bitch should be monitored for signs of uterine disease, as she may develop
cystic endometrial hyperplasia / pyometra after ovulation induction. For bitches
not intended for breeding, and for those bitches that do not respond to medical
treatment in 7 to 10 days, OHE is the treatment of choice.
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- Neoplasia
Primary ovarian neoplasia is uncommon in the dog. Some may be productive tumors,
with excessive and/or persistent levels of progesterone and estrogen causing
paraneoplastic syndromes referable to actions of the hormone present.
Most ovarian tumors are palpable as masses in the mid- to cranial abdomen.
Radiographs verify tissue location of the mass and are used to assess for
metastasis.
i) Sex cord/Stromal tumor = Granulosa cell tumor. This is the most common
primary ovarian neoplasm in the dog. These usually occur in older bitches,
and may be more prevalent in nulliparous bitches. Clinical presentation includes
a history of progressive abdominal distension. Functional granulosa cell tumors
may produce estrogen causing vulvar enlargement, serosanguinous vulvar discharge,
persistent estrus and occasionally pancytopenia, progesterone causing CEH/pyometra,
or both. Eighty percent of these tumors do not metastasize so surgical removal
usually is curative.
ii) Germ cell tumors = teratoma (benign) and dysgerminoma (malignant)
Treatment - Complete OHE. Tumors are often bilateral, direct extension to
the uterus may occur, and older bitches with ovarian disease may be even more
predisposed to uterine disease.
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- Metritis
Metritis does not equal pyometra!
Metritis occurs postpartum. It is caused by ascending infection following
normal parturition or abortion, fetal infection, dystocia, and/or retention
of placentas. Clinical presentation includes fever, anorexia, depression,
neglect of pups and exudation of foul-smelling purulent vulvar discharge.
Diagnose by demonstration of leukocytosis with left shift on CBC, demonstration
of purulence of vulvar discharge by cytology, and/or culture of bacteria from
vulvar discharge. Abdominal radiographs and/or ultrasound can be used to diagnose
retention of placentas and/or feti.
Treat by promoting evacuation of uterine contents with oxytocin at a dose
of 1 IU/kg IM or PGF-2a at a dose of 0.25 mg/kg
SQ, and treatment of infection with an antibiotic chosen via culture and sensitivity.
While awaiting culture results, start on a broad spectrum antibiotic; as metritis
is most commonly caused by Gram negative enterobacters, ampicillin is a common
choice (20 mg/kg PO TID). As long as the bitch does not show evidence of toxemia,
pups can be allowed to nurse.
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- Subinvolution of placental sites (SIPS)
This is a disorder that most commonly occurs in young bitches after whelping
their first litter. They will present with excessive or prolonged sanguinous
vulvar discharge postpartum (remember the normal exudation of lochia for 3
weeks post-whelping). The discharge is cytologically non-purulent and the
bitch is normal in all other respects.
Diagnostic tests to be run include cytology and culture of vaginal discharge
(to assess for presence of infection), careful abdominal palpation +/- radiography
and/or ultrasound (to rule out metritis, retained placentas or feti), CBC
(to rule out metritis and monitor PCV in bitch with chronic hemorrhage), and
testing for brucellosis. Definitive diagnosis rarely is performed as it requires
histologic examination of placental sites; on gross examination, affected
sites are larger than involuted sites and contain nodular protrusions of endometrium.
Histologically, these nodules are made up of eosinophilic tissue with necrosis
and hemorrhage. The persistent hemorrhage is due to failure of the normal
thrombosis and occlusion of endometrial blood vessels which occurs as part
of the involution process.
Treat by OHE in bitches not intended for breeding in the future, and supportive
care for those left intact. Monitor the PCV and transfuse if necessary, and
give antibiotics if secondary reproductive tract infection develops.
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- Cystic endometrial hyperplasia (CEH) / Pyometra
Pyometra does not equal metritis!
The initial insult is development of CEH. CEH develops due to repeated prolonged
exposure of the estrogen-primed uterus to progesterone (estrogen increases
the number of progesterone receptors in the endometrium). Bitches are prone
to uterine disease due to the unique nature of cycling in the dog. Most bitches
older than 5 to 6 years of age have some degree of CEH. Exogenously administered
estrogens and progestogens can induce CEH and subsequent pyometra. Pyometra
develops when ascending infection overlies CEH. E coli is the organism
most commonly isolated.
To view a gross pathologic image
of CEH, click here.
Presenting history is of a bitch usually older than 5 to 6 years of age who
was in heat 1 to 12 weeks ago, and who is currently exhibiting anorexia, depression,
PU/PD, abdominal distension, and possibly purulent vulvar discharge (variable,
depending on patency of cervix). Signs of septic shock, vomiting and diarrhea
may also be present, especially late in the course of the disease. On physical
examination, vulvar discharge may or may not be present and the uterus will
be palpably enlarged. Be cautious with abdominal palpation; overly aggressive
palpation of the friable, distended uterus may induce uterine rupture.
Diagnosis involves demonstration of uterine enlargement and non-pregnancy
(remember, we're in diestrus) by radiography and/or ultrasound. Immature neutrophilia
will be present, with higher WBC number if the cervix is closed. Changes on
a serum chemistry profile include increased BUN and increased total plasma
protein (globulins). Urine will be normal to dilute and proteinuria may or
may not be present. The vaginal discharge will be cytologically purulent.
To view an image of CEH on ultrasound,
click here.
To view an image of purulent
vaginal discharge cytology, click here.
Treatment is dependent on cervical patency. Students often ask about placing
drains through the cervix to bypass the problem of cervical patency. There
are few such reports in the literature, with most using catheters as a path
by which intrauterine fluid can drain along the catheters rather than through
them. Success has been variable and most reports have included medical therapy
(prostaglandin) along with the catheter placement for success. I have not
tried these techniques nor do I know of anyone who considers them a likely
alternative for the treatments listed below.
* Closed cervix
- OHE + fluids + antibiotics
1) Correct fluid deficit
2) Culture cranial vagina, start bitch on
ampicillin (20 mg/kg PO TID)
3) OHE as soon as stable
* Open cervix
- OHE + fluids + antibiotics
As above - OHE is always the best treatment
since the bitch with pyometra has underlying
CEH which will probably always be present.
Pyometra is an acute manifestation of a
chronic disease process.
- PGF-2a
Four criteria required for medical treatment of pyometra are an open cervix
(evidenced by vulvar discharge), the bitch is still of breeding age (generally
less than about 6 years of age) and is valuable in a breeding program and
the bitch is not azotemic.
1) Determine uterine size (to follow progress)
2) Culture and sensitivity of vaginal discharge
3) Start bitch on ampicillin (20 mg/kg PO TID).
Change antibiotic if necessary based
on sensitivity. Continue antibiotic for
1 month.
4) PGF-2a (Lutalyse - Upjohn) at dose of
250 mcg/kg SQ SID x 2 to 7 days,
until uterine size nears normal. If the
bitch is still in diestrus, administer BID
to lyse CL and decrease progesterone.
5) Recheck bitch 2 to 4 weeks after therapy is
concluded. Vulvar discharge may
persist for up to 1 month. If vulvar
discharge is increasing in volume or
uterine size has increased, consider
repeat of PGF-2a therapy or OHE.
6) At next proestrus, collect an anterior vaginal
culture and treat with an appropriate
antibiotic for 3 weeks. Breed at that
season. If she does not conceive,
consider luteolysis with PGF-2a to de-
crease progesterone effect and
recurrence of pyometra. OHE as
soon as breeding life over!
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- Vaginitis
* Prepuberal = puppy vaginitis. This appears prior to the first estrus. The
dog presents with a history of small amounts of clear to cloudy sticky vulvar
discharge with occasional vulvar licking, and rarely presents with systemic
signs.
* Adult vaginitis. This appears after the first estrus and in spayed females.
Signs are similar to those above. Vulvar discharge may be copious and the
bitch may attract male dogs.
Physical examination findings are all normal except in the genital system.
Assess for uterine enlargement and perform a digital vaginal examination to
assess for presence of anatomic abnormalities predisposing to infection.
Diagnose by anterior vaginal culture and sensitivity (remember that the vagina
is not a sterile environment). Perform vaginal cytology; vulvar discharge
may be a normal indication of estrus in an intact dog. Check for brucellosis.
Make sure to differentiate from urinary tract disease.
Treatment - Puppy vaginitis often resolves spontaneously, and may be more
likely to resolve spontaneously if the bitch is allowed to go through one
estrous cycle. Treat with a 4 week course of a specific antibiotic only after
ruling out or treating all underlying problems (e.g. vaginal strictures, urinary
incontinence, pyometra). Some dogs may respond to topical therapy with triple-antibiotic
ophthalmic ointment. Spayed dogs may benefit from low-dose estrogen therapy.
Veterinarians at Colorado State University recommend a therapeutic trial with
phenylpropanolamine as used for urinary incontinence in bitches with idiopathic
vaginitis, assuming subclinical urine leakage into the vaginal vault through
an incompetent urethral sphincter.
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- Vaginal prolapse
Signalment - This occurs in intact, young, large breed dogs. It almost always
occurs during proestrus or estrus, occasionally at parturition. Estrogen stimulus
causes edematous enlargement of the vagina with subsequent protrusion of the
vaginal mucosa through the vulvar lips.
Three stages: Stage I = perineal swelling, Stage II = eversion of vaginal
floor (hyperplastic change originates just cranial to urethral papilla), Stage
III = eversion of entire vaginal circumference.
To view an image of stage
II vaginal prolapse, click here.
To view an image of stage
III vaginal prolapse, click here.
Treatment - If the bitch can be spayed, OHE! If the bitch is to be left intact,
treat with topical soothing lubricants and an Elizabethan collar and consider
administration of GnRH to induce ovulation. Surgical resection may be necessary.
Recurrence is common in dogs without surgical resection (2/3), but may even
recur after surgery. Purse-string sutures and pexy- procedures are not recommended
as secondary infection may occur.
* Differentiation of vaginal prolapse and vaginal neoplasia *
|
Vaginal prolapse
|
Vaginal neoplasia
|
| Young dogs |
Older dogs |
| Arises from vaginal floor cranial to urethral papilla |
Arises anywhere in vagina |
| Appearance and progression vary with estrous cycle |
Appearance and progression do not vary with estrous cycle |
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- Neoplasia
Leiomyoma and TVT most common.
Patients with vaginal neoplasia present with clinical signs of bulging of
the perineal region, dysuria or pollakiuria, and/or bulging of tumor tissue
through the vulva. Diagnose by exfoliative cytology or histopath after core
or excision biopsy. Treatment of vaginal tumors consists of surgical removal.
To view an image of a vaginal
leiomyoma, click here.
TVT = transmissible venereal tumor = naturally occurring neoplasm with unique
chromosome complement (2n = 59), transmitted by transplantation to external
genitalia at mating. It appears as single or multiple nodules or pedunculated
cauliflower-like friable masses on the genitalia. Transplantation to nasal
mucosa and other tissues can occur. Tumor behavior varies depending on host's
immune status. Treat with vincristine +/- surgical debulking.
To view an image of a vaginal
TVT, click here.
- False pregnancy
This is a normal phenomenon in which the dog exhibits nesting behavior, lactation
and possibly maternal protection of inanimate objects as a response to the
normal decline in serum progesterone at the end of diestrus. This can be mimicked
by withdrawal of exogenous progestogen therapy or OHE during diestrus.
No other reproductive tract condition predisposes a bitch to false pregnancy
or vice versa. Belgian researchers have some evidence that false pregnancy
may be associated with mammary neoplasia, presumably secondary to distension
of the mammae with milk and subsequent hypoxia and free radical formation.
Treatment - Spontaneous remission - Light sedation with hot and/or cold compresses
of mammary glands may help very uncomfortable animals. Do not treat with phenothiazine
tranquilizers (e.g. acepromazine), which may inhibit dopamine and potentiate
prolactin secretion. Mibolerone at 18 mcg/LB PO x 5 days is reported to alleviate
signs of false pregnancy (not approved). Testosterone cypionate (0.5 to 1.0
mg/kg IM once) decreases milk production in dogs (not approved). Pseudopregnancy
can also be treated with prolactin inhibitors (bromocriptine, cabergoline).
Do not use progestogens; the dog will relapse after therapy is discontinued.
OHE is not curative.
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- Mastitis
Mastitis is most commonly due to ascending or hematogenous infection with
coliforms, Staph or Strep sp. in the first week of lactation.
Infected mammary glands are enlarged, hot and painful. The bitch exhibits
pyrexia and neglect of pups. The CBC shows immature neutrophilia. Abscessation
and gangrene of mammary tissue may be present.
Treatment - Start on broad spectrum antibiotics until culture and sensitivity
results are back. If abscessation or necrotic tissues are present, the areas
should be surgically drained and debrided, leaving them open to heal by second
intention. Warm soaks or hot packing may be beneficial. Aspirin can be given
for its antipyretic and analgesic effects. Pups need not be weaned unless
abscessation is present.
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- Agalactia
Agalactia is poorly documented in the bitch. Treat with oxytocin therapy (Syntocinon).
Oxytocin aids in milk letdown only, not in milk production. Acupuncture also
can be used to stimulate lactation in bitches as can treatment with the dopamine
antagonist, metoclopramide (0.1 - 0.2 mg/kg BID to TID - watch for behavior
changes; causes depression in women) or domperidone (2.2 mg/kg per os BID).
- Mammary neoplasia - Need a review of oncology
terminology?
This is the most common neoplasm in female dogs.
Signalment - Mammary neoplasia is most common in bitches over 6 years of age,
those left intact (bitches spayed before 2.5 years of age or 4 estrous cycles
have decreased risk of developing mammary neoplasia with greatest benefit
if spayed before puberal estrus), and in purebreds (compared to crossbreds)
with tumors most often arising in the caudal pair of mammae.
Many types of tumors may arise in mammary tissue with many patterns of metastasis
possible. In the dog, 50% of mammary tumors are benign fibroadenomas (=mixed
mammary tumor) and 50% are malignant adenocarcinomas. The most common sites
of metastasis for adenocarcinoma are the regional lymph nodes (axillary LN
drain 3 cranial mammae, superficial inguinal LN drain 2 caudal mammae) and
lungs. Many of these tumors contain receptors for estrogen and progesterone.
The mammary gland of dogs is more sensitive to neoplastic transformation due
to progesterone than is mammary tissue in other species. This effect may be
mediated by growth hormone.
Diagnose by palpation of masses in 1 or more glands. More than one mass is
present in the majority of cases. Systemic signs vary with pattern of metastasis.
Needle aspirate, scraping of ulcerated lesions or cytology of fluid from affected
glands may yield useful information in diagnosis of malignancy, but lack of
neoplastic cells does not imply that malignancy is not present. Definitive
diagnosis requires histopath on an excision biopsy sample.
Treatment - Surgical removal +/- OHE - If OHE is performed at the same time
as tumor removal, do the OHE first to prevent seeding of the abdomen with
neoplastic cells.
* Lumpectomy = removal of mass only
* Simple mastectomy = removal of gland containing mass
* En bloc dissection = removal of mass, gland, intervening lymphatics, and
regional LN
* Unilateral mastectomy = removal of entire chain of glands +/- regional LN
No definitive studies have been done that determine which technique is associated
with best survival time. In women, studies suggest that more radical therapy
is not necessarily correlated with improved survival time. Chemotherapy, radiation
therapy, and immunotherapy are possible, but are not well characterized in
the dog.
Prognosis - Prognosis is very good with benign masses, and poor to good with
malignant masses with poorest prognosis associated with tumors greater than
2 to 3 cm is diameter or the presence of metastasis (75% survive < 2 years
after surgical removal of primary tumor).
Return to Table of Contents
CANINE - MALE
Anatomy and physiology
- Puberty, defined as presence of spermatozoa in the ejaculate and normal
breeding behaviors, occurs from 6 to 24 months of age, with an average of
10 to 12 months of age.
- Anatomy:
The two testicles should be completely descended by 6 months of age. The two testicles should be completely descended by
6 months of age. Testicular size varies with size of the dog. and can be evaluted
by measurement of total scrotal width (Woodall PG, Johnstone IP. J Sm Anim
Prac 1988;29:543). The prostate is the only accessory sex gland. The
penis of canids contains a bone, the os penis.
-
|
BODY WEIGHT (kg) [lbs]
|
AVERAGE TOTAL SCROTAL WIDTH (mm)
|
ACCEPTABLE RANGE FOR TOTAL SCROTAL WIDTH (mm)
|
|
5 [11]
|
30
|
24-35
|
|
10 [22]
|
37
|
31-45
|
|
15 [33]
|
42
|
35-50
|
|
20 [44]
|
47
|
38-56
|
|
25 [55]
|
49
|
41-60
|
|
30 [66]
|
55
|
43-64
|
|
35 [77]
|
57
|
46-68
|
|
40 [88]
|
59
|
48-74
|
|
45 [99]
|
63
|
49-76
|
|
50 [110]
|
64
|
50-77
|
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Techniques
- Semen collection and evaluation
- Semen collection
i) Equipment - Teaser bitch (may increase number of sperm in ejaculate), collection
vessel (AV, syringe case, cup or plastic bag)
To view an image of semen collection
equipment, click here.
ii) Technique
The dog is manually stimulated through the prepuce. As erection begins, the
prepuce is pushed caudal to the bulbus glandis and the artificial vagina (AV)
introduced. The fingers encircle the penis caudal to the bulbus glandis tightly,
simulating contraction of the constrictor vestibulae muscles during the copulatory
lock (=tie). Three fractions of semen are ejaculated; the clear pre-sperm,
cloudy sperm-rich (thrusting behavior) and clear prostatic fluid fractions
(rhythmic anal contractions and urethral pulsations). When you are done collecting
semen, release the grip caudal to the bulbus and gently peel off the AV. Ensure
detumescence and replacement of penis within the prepuce prior to kenneling
the dog.
To view an image of semen
collection in the dog, click here.
Return to Table of Contents
- Semen evaluation
i) Color - Normal = milky, red or brown = blood, yellow = urine, green = pus
ii) Volume (ml/ejaculate) - Normal = 1 to 30 ml, extremely variable
iii) pH - prostatic fraction only. Normal 6.5 to 7.0 - pH may be used to direct
antibiotic therapy in prostatic disease (see Prostatitis).
iv) Progressive motility - Look at one drop of semen on a warmed glass slide
with or without extender. Normal = > 70%
v) Concentration (sperm/ml) - Hemacytometer and WBC Unopette system. Count
center square to get number of million sperm per milliliter. The normal number
is variable as it is dependent on the volume of prostatic fluid collected.
vi) Total sperm number (sperm/ejaculate) = volume x concentration. Normal
= 300 to 2000 million. Larger dogs make more sperm as they possess a larger
mass of spermatogenic tissue.
vii) Morphology - Stain with eosin-nigrosin (SFT Morphology stain) or DiffQuik
stains. Normal = > 80% morphologically normal sperm. Examine at least 100
individual sperm under the oil immersion objective. Correlation of defects
with fertility is unknown in the dog.
To view an image of canine
spermatozoa on phase contrast microscopy, click here.
To view an image of canine
spermatozoa stained with DiffQuik,click here.
To view an image of canine
spermatozoa stained with eosin-nigrosin (SFT) stain, click here.
To view a chart of morphologic abnormalities in the
dog, click here.
viii) Cytology - Examine the sample for abnormal cells, bacteria, and/or inflammatory
cells.
ix) Microbial culture - Aerobes, anaerobes, Mycoplasma. Perform a quantitative
culture with > 10,000 bacteria (CFU) per ml indicative of significant overgrowth
of an organism.
The correlation between inflammatory cytology and presence of infection is
not 100%. Perform a culture even if the cytology is normal if you are suspicious
of reproductive tract infection (e.g. recurrent prostatitis or cystitis, infertility).
- Prostatic palpation and massage
The normal prostate is palpable on rectal examination as a bilobed symmetrical
organ 2 to 3 cm caudal to the pelvic brim. As the animal ages, the prostate
enlarges (see BPH), and may be pulled cranially to the point where it may
be palpable per abdomen. The prostate secretes fluid constitutively; this
prostatic fluid normally drips down into the bladder and out the penile urethra.
Prostatic massage is used for collection of prostatic fluid from dogs that
cannot or will not ejaculate. The dog is sedated if necessary, and placed
in lateral recumbency. A sterile polypropylene urinary catheter is used to
empty the urinary bladder which is then flushed with 3 to 5 ml sterile saline.
A gloved finger is inserted into the rectum and the urinary catheter withdrawn
until its tip is palpable in the post-prostatic urethra. The catheter is then
advanced until it is judged to be within the prostatic urethra. A volume of
1 to 2 ml sterile saline is flushed in while the prostate is massaged vigorously
for 1 minute. Fluid and cells are aspirated and submitted for culture and
cytology.
Return to Table of Contents
Abnormalities of ...
- Congenital defects
- Balanoposthitis
= inflammation of penile and preputial mucosa. The condition is usually caused
by opportunistic invasion of normal flora. Affected dogs may show preputial
discharge and/or excessive licking. Diagnose by physicalsigns and culture;
treat with local and systemic specific antibiotic therapy.
- Phimosis / Paraphimosis
Phimosis = inability to extrude penis. This may be due to congenital or induced
stenosis of the preputial orifice.
Paraphimosis = extruded penis cannot be withdrawn into prepuce. Paraphimosis
may follow normal copulation or may be due to presence of a hair ring decreasing
vascular outflow or physical movement of the penis. Treat by lubrication.
If recurrent, this condition may respond to therapy with progestogens (megestrol
acetate 0.5 mg/kg once daily per os for a maximum of 30 days) or may require
surgical enlargement of the preputial orifice.
- Neoplasia
TVT, skin tumors
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- Cryptorchidism
= lack of descent of one or both testicles into the scrotum by 6 months of
age. The retained testicle(s) may be found at the inguinal ring, in the inguinal
canal, or in the abdomen
.
Normal testicular descent - The testes develop initially caudal to the kidneys,
attached to the superficial inguinal ring by the gubernaculum testis. The
gubernaculum grows, pulling the testicle through the abdomen and inguinal
canal, and then shrinks, pulling the testicle into the scrotum. The process
is dependent on physical presence of the testis. Testosterone is important
only late in descent. Factors controlling gubernacular outgrowth are unknown.
Cryptorchidism is due to hormonal, genetic and/or physical-environmental factors
altering gubernacular outgrowth and movement of the testis. In rats, cryptorchidism
is associated wtih decreased androgen secretion, decreased smooth muscle content
in the gubernaculum or decreased sympathetic tone in the gubernaculum. Canine
cryptorchidism is believed to be a sex-limited hereditary trait with transmission
due to a single autosomal recessive gene. The genetic predisposition may be
carried by males or females, although it will only be manifested in males.
Incidence - This is a common disorder with purebred dogs more susceptible
than crossbreds (perhaps due to inbreeding), with toy breeds predisposed,
and unilateral cryptorchidism more common than bilateral with the right side
more commonly retained.
The risk of testicular neoplasia and torsion is increased in retained testicles.
The unilateral cryptorchid is fertile. Retained testicles are incapable of
spermatogenesis due to elevated abdominal temperature destroying spermatogenic
tissues, but are capable of steroidogenesis.
Breeding of unilateral cryptorchids should be discouraged. Neuter them! This
condition is hereditary, and the dog is at increased risk of testicular torsion
and neoplasia. Cryptorchid dogs cannot be shown in AKC sanctioned dog shows.
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- Orchitis/Epididymitis
= inflammation of the testicular and/or epididymal tissue due to bacterial
infection after penetrating injury or hematogenous introduction of bacteria,
traumatic, or autoimmune causes. Brucellosis is associated with epididymitis
in dogs. The dog will be painful, the scrotum reddened and the testicles palpably
enlarged. Diagnose by physical examination findings, needle aspirate of the
affected testicle, CBC (immature neutrophilia) and/or serology for brucellosis.
Treat with specific antibiotics and/or castration. Prognosis for future fertility
is guarded as inflammation = increased temperature within the scrotum = decreased
spermatogenesis.
- Neoplasia
Testicular neoplasia is the second most common type of neoplasia in male dogs
(skin #1).
Three types exist; all are equally common in scrotal testicles. Incidence
of testicular neoplasia is increased in animals over age 8. It may be uni-
or bilateral and more than 1 tumor type may be present. Bilateral castration
is the treatment of choice for all types.
* Sertoli cell tumor - Arises from Sertoli cells - Large - This is the type
most likely to produce a paraneoplastic syndrome due to production of estrogen,
with gynecomastia, attraction of male dogs, pendulous penile sheath, alopecia
and blood dyscrasias. The non-neoplastic testicle atrophies due to increased
scrotal temperature and negative feedback of excessive gonadal steroids from
the neoplastic testicle. Sertoli cell tumors are the most common type in abdominally
retained testicles.
* Seminoma - Arises from germ cells. Paraneoplastic syndromes are uncommon.
These are the most common type in inguinally retained testicles.
* Interstitial cell tumor - Arises from interstitial (Leydig) cells - Small
- These occasionally produce paraneoplastic syndromes.
Treatment = castration. You can do a unilateral orchiectomy in a valuable
breeding dog but be aware that fertility may be reduced due to atrophy or
undetected neoplasia in the testicle left behind. Signs of paraneoplastic
syndromes regress with tumor removal. Prognosis is good; while the occurrence
of metastasis varies greatly, it is generally <10%. Prognosis is worse
if pancytopenia is present.
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- Benign prostatic hypertrophy (BPH)
= enlargement of the prostate, unassociated with infection
BPH occurs in intact dogs. It occurs to some degree in all intact dogs >
5 years of age. The aging prostate in dogs and man secretes increasing amounts
of estradiol which increases prostatic receptors for a testosterone metabolite,
5-a-dihydrotestosterone, which increases prostatic
size.
The dog may be asymptomatic or show clinical signs consisting of dripping
bloody fluid from the penis unassociated with urination, blood in the semen,
or hematuria. No systemic signs are usually present..
Palpation - The prostate is symmetrically enlarged and non-painful.
Diagnosis - This list of diagnostic tests is applicable for all prostatic
disease conditions.
* Cytology and culture of prostatic fluid, collected by ejaculate or prostatic
massage
* Survey radiographs of the caudal abdomen
* Retrograde cystourethrography
* Prostatic ultrasound
* Prostatic aspirate or biopsy
In BPH, no significant changes besides prostatic enlargement are noted. The
diagnosis can be verified by prostatic biopsy or aspirate but these tests
only define the condition in the part of the prostate that was sampled.
Treatment:
* Surgical = castration
* Medical - In breeding dogs, you may treat
with progestogens (e.g. Ovaban at 1 mg/lb for up to 2 weeks) or 5-alpha reductase
inhibitors (Finasteride [Proscar™] at 0.1 - 0.5 mg/kg/day). Progestogens
act by exerting negative feedback to the pituitary, decreasing release of
LH and testostesterone and have not been demonstrated to be detrimental to
spermatogenesis. Finasteride causes a decrease in prostate size within one
month of therapy and does not appear to affect semen quality or libido. Other
treatments used in men (e.g. nutritional supplements, doxazosin mesylate [Cardura™])
have not been evaluated in the dog. Herbal therapy (saw palmetto) has been
shown not to be efficacious in dogs with BPH. If the male with BPH is to continue
breeding, you may see adequate reproductive performance, even with blood in
the semen. Monitor with quantitative semen cultures every 4 to 6 months to
catch early onset of prostatitis, which will decrease fertility. The long
range plan = castration as soon as the dog's breeding life is over.
Return to Table of Contents
- Prostatitis
= prostatic inflammation associated with infection
Prostatitis occurs in intact dogs. Ascending infection is often superimposed
on BPH. The clinical presentation varies. In acute prostatitis, the dog is
painful, with a stilted gait in the rear limbs, fever and anorexia. He may
be painful when ejaculating. In chronic prostatitis, the dog may be asymptomatic
or show intermittent signs of urinary tract disease.
Palpation - The prostate may be asymmetrical. If cysts or abscesses are present,
the prostate may be greatly enlarged.
Diagnosis - See the list of diagnostic tests under BPH. Cytology of prostatic
fluid will be inflammatory, and cultures of prostatic fluid positive (>
10,000 CFU per ml, most common organisms E. coli, Staph and Strep
sp.). On retrograde cystourethrography, the contrast medium will move out
into the honeycomb of prostatic tissue and may fill cystic spaces. On ultrasound,
the prostatic tissue may appear mottled. If an abscess is present, it will
be visible as a round, fluid-filled structure within the parenchyma. Prostatic
biopsy is contraindicated if infection is present.
Treatment - Appropriate antibiotic therapy is the treatment of choice. The
antibiotic used must diffuse into prostatic tissue. You can base your antibiotic
choice on pH; if the prostatic fluid is acidic, weak bases should be trapped
within the prostatic tissue. Trimethoprim sulfa, chloramphenicol, and Baytril
are known to diffuse well into prostatic tissue. Treat for 3 to 4 weeks, recheck
cultures at 7 weeks and 3 to 4 weeks post-treatment if necessary. Castration
will decrease prostatic size and increase the chance of clearing prostatitis
but do not perform castration in the presence of uncontrolled reproductive
tract infection. Treatment of prostatic abscesses may involve surgical resection
of the abscess (some research suggests marsupialization of the abscess or
packing of the cavity with omentum hastens recovery and decreases recurrence)
or ultrasound-guided aspiration of purulent material. Appropriate antibiotic
therapy is paramount prior to these procedures.
Return to Table of Contents
- Neoplasia
The most common prostatic neoplasm is malignant adenocarcinoma.
Prostatic neoplasia occurs in intact or neutered dogs. One study suggested
that neutered dogs may have 2X more risk of developing this tumor than intact
dogs. There is no known hormonal influence. It is most common in older dogs.
Dogs may present with a wide array of clinical signs, varying with the pattern
of metastasis. These include stilted gait, tenesmus, dysuria, emaciation,
rear limb weakness, and lumbar pain. Metastasis occurs most often in iliac
LN, lungs, urinary bladder, periprostatic tissue, rectum, bone, and kidney.
Palpation - The neoplastic prostate is usually enlarged, firm and nodular
and may be asymmetrical. You may be able to palpate enlarged sublumbar LN.
Diagnosis - See the list of diagnostic tests under BPH. You may see exfoliated
neoplastic cells on cytology. Retrograde cystourethrography reveals prostatic
enlargement, disruption of the smooth mural surface of the urethra, and/or
excessive movement of contrast medium into the gland. On ultrasound, the gland
will appear mottled with hyperechoic areas suggestive of calcification. Definitive
diagnosis is based on cytologic samples of prostatic fluid, or biopsy or aspirate
samples of prostatic parenchyma. Cytologic examination of prostatic fluid
is less invasive and should be performed first.
Treatment - Prostatectomy is not the treatment of choice. No hormonal therapy
is known to be effective. The prognosis is grave as metastasis usually already
has occurred when the dog is diagnosed.
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CANINE - GENERAL
Artificial insemination
- Fresh semen
Semen collection: Routine
Semen handling: None
Storage: None
Shipment: None
Insemination: Vaginal
- Fresh chilled semen
Semen collection: Routine
Semen handling: The semen is mixed with extender which serves to increase
semen volume, protect against changes in temperature and pH, provide nutrients
and decrease bacterial growth.
Storage: None
Shipment: Must reach destination within 24 hours
Insemination: Vaginal
- Frozen semen
Semen collection: Routine - Recommend a breeding soundness examination beforehand.
Semen handling: The semen is mixed with extender and cryoprotectant, then
frozen in straws or pellets.
Storage: Liquid nitrogen
Shipment: No time limit, must be maintained in liquid nitrogen canister
Insemination: Intrauterine
- Insemination volume
Vaginal
1.5 to 3 ml for
bitches weighing less than 10 pounds
3 to 5 ml for
bitches weighing 10 to 50 pounds
5 to 8 ml for
bitches weighing more than 50 pounds
Intrauterine
Even very small
volumes will distend the uterine body and both uterine horns. Excessive volume
(more than 4 to 5 ml) will leak through the cervix readily.
- Conception rates
Natural service > Fresh AI > Fresh chilled > Frozen
Return to Table of Contents
Brucellosis
The etiologic agent is Brucella canis. Canine brucellosis is
a zoonotic disease.
Transmission occurs primarily via ingestion, secondarily by venereal or congenital
routes. The prepatent period is 1 to 3 months. Bacteremia with no fever may
persist for 6 to 12 months. This bacterium eludes the immune system by persisting
inside macrophages and PMNs.
Clinical history:
Both genders: Asymptomatic, occasional cause of vertebral discospondylitis
Females: Abortion late in gestation, persistent vaginal discharge, infertility
Males: Orchitis, epididymitis, scrotal irritation, poor semen quality, infertility
Diagnosis:
- Serologic tests - Dog must be off antibiotics for 4 weeks prior to testing
* Rapid slide agglutination test (RSAT) - This test is sensitive but not specific.
False positives are due to cross-reaction with Bordetella, Pseudomonas, Staph
sp., etc. The RSAT becomes positive earliest of all serologic tests in a
true infection. All positives should be rechecked!
* Tube agglutination test (TAT) - Gives a titre instead of just a yes/no answer.
The same problem with false positives exists as described above.
* Agar gel immunodiffusion test (AGID) - This test is performed at Cornell University.
It identifies cytoplasmic antigens (very specific) and cell wall antigens (less
specific). This test remains positive longer after the animal becomes abacteremic.
Chronically infected animals are intermittently bacteremic, and show an intermittent
decrease in titres. Chronically infected animals may therefore test negative
falsely with any test. If you are unsure, 3 negative tests at monthly intervals
are required to call a suspicious animal truly negative.
- Culture - This is definitive but difficult. Consider blood, LN aspirates,
and obvious samples such as aborted tissues and vaginal or preputial discharge
for culture.
Treatment: OHE or castration should be performed as gonadectomized animals shed
fewer organisms. Consider euthanasia, especially in kennel situations. Antibiotic
therapy may decrease titres but is not curative.
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Early spay/neuter
Definition:
= surgical sterilization of sexually immature animals
Pros:
* Control of pet overpopulation - Animals gonadectomized before placement from
humane societies, shelters, pet stores, or breeders
* Surgery quick with minimal bleeding
* No scientific reason exists for traditionally recommended time of gonadectomy
* Studies done to date have not demonstrated negative short-term or long-term
side-effects of prepuberal gonadectomy in dogs or cats
Cons:
* Anesthesia/surgery concerns in pediatric animals
To view an image of ovariohysterectomy
of a 7-week-old kitten, click here.
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FELINE - FEMALE
Anatomy
Estrous cycle
Cats are seasonally polyestrous. In natural light, queens will cycle from January
to mid-October. They can be induced to cycle year-round with artificially increased
daylength (14 to 16 hours light daily).
- Puberty
Queens enter puberty at 4 to 12 months of age or when they reach 2.3 to 2.5
kg in weight. Puberty onset is dependent on season. Long-haired breeds and
Manx cats show later puberty onset.
- Stages
- Proestrus
Rarely observed in cats
- Estrus
Length = 6 to 10 days, range 12 hours to 19 days, +/- effect of breeding
Clinical appearance - Signs of heat include lordosis, vocalization, increased
affection, positive stimulation and allowing the male to mount.
Vaginal cytology - Vaginal epithelial cells will become cornified, but not
to the same degree as in canine samples.
To view an image of lordosis
in a cat, click here.
- Postestrus
= period after an estrus during which the queen was not induced to ovulate.
Length = 13 to 18 days.
- Diestrus
= period after an estrus during which the queen was induced to ovulate. The
CL persists and progesterone is produced. Length if a fertile mating occurred
(= gestation length) is about 65 to 66 days with range of 63 to 71. If a non-fertile
mating occurred, pseudopregnancy will follow, with a length of 40 to 50 days.
- Anestrus
Seasonal
- Induced ovulation
Induced ovulators include the domestic cat, ferret, rabbit, mink, skunk, 13-lined
ground squirrel, camel, llama, short-tailed shrew and giant fruit bat, and
possibly the tiger, cheetah and jaguar.
An external trigger, usually coitus, is required for stimulation of GnRH release
and the subsequent LH surge inducing ovulation. The amount of LH released
is dependent on the timing and number of copulations; 50% of queens bred only
once showed progesterones indicative of ovulation, while 100% of those mated
at least 4 times apparently ovulated.
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FELINE - MALE
Anatomy
Accessory sex glands = prostate and bulbourethral glands
Penis - Penile "spines" = cornified papillae which encircle the penis.
These spines appear at puberty and disappear with castration (androgen-dependent).
FELINE - GENERAL
Breeding/Artificial insemination
- Breeding
- Mount
- Intromission and ejaculation
- Dismount and "after reaction"
- Remount
Semen is deposited into the posterior vagina; the erect penis of the tomcat
is too short and too large to reach the queen's cervix.
To view an image of normal
cat breeding behavior, click here.
- Artificial insemination - Rarely performed
- Semen collection by artificial vagina or electroejaculation
- Semen deposited vaginally
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Pregnancy/Parturition
- Gestation length = 65 to 66 days with wide normal range. The literature
reports 100% incidence of stillbirth or early postnatal deaths in litters
with gestation length of < 61 days.
- Placentation = endotheliochorial, zonary as in dog
- Pregnancy diagnosis - Abdominal palpation can be performed at 21 to 25 days,
ultrasound is not commonly used and radiography can be used after about day
38 to 40. Radiographic measurement of fetal crown-rump length can be used
to estimate fetal age as can degree of mineralization.
To view a chart showing correlation of fetal mineralization
with gestational age in cats, click here.
- Parturition - The stages are the same as in the dog. Dystocia is uncommon.
Normal parturition can take > 24 hours; in our colony, median parturition
length was 8 hours, with a range of 4 to 42 hours.
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Abnormalities of ...
- Sexual differentiation
Male calico and tortoiseshell cats - White coat color is on an autosome while
black and orange are on the X chromosome. A male, with 1 X, should therefore
only be able to exhibit orange or black, not both. If he exhibits both, he
probably has an abnormal karyotype (e.g. XXY, XX/XY chimera). These cats usually
are sterile.
- Female cats
- Ovarian remnant syndrome
= presence of functional ovarian tissue in a previously ovariohysterectomized
queen
Causes:
* Surgeon error - Improper placement of clamps or ligatures, inadvertent deposition
of ovarian tissue in abdomen. One study found that < 50% of cases evaluated
had been spayed by new graduates :)
* Congenital anomaly? - Presence of completely or partially separated piece
of normal ovary near the main ovary or in the broad ligament
* Drugs?
Presentation:
Post-surgical onset is variable but once cycles are resumed, they assume normal
periodicity. The cat exhibits normal signs of estrus and attracts tomcats.
Diagnosis:
* Vaginal cytology - Cytology will be cornified when the cat is showing signs
of behavioral estrus.
To view an image
of non-cornified feline vaginal cytology, click here.
To view an image of
cornified feline vaginal cytology, click here.
* Hormone assays
Resting:
- Estradiol - Not accurate. Cytology is more accurate as a bioassay.
- Progesterone - Will be low as cats are induced ovulators
Challenge:
- Give GnRH (25 mcg/cat IM) while the cat is in estrus. Recheck progesterone
in 2 to 3 weeks. If the serum progesterone concentration is high (> 2 ng/ml),
you have proven that luteinized ovarian tissue is present.
* Exploratory laparotomy
Treatment:
* Medical - Estrus-suppressing drugs. None are approved for use in cats, and
this would have to be life-long therapy.
* Surgical - Perform an exploratory laparotomy when the cat is exhibiting
signs of estrus (follicular structures on remnant) or after induction of luteinization
of tissue (luteal structures on remnant).
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- Mammary hypertrophy
This condition is usually seen in young intact females following estrus, and
in male and female cats receiving long-term therapy with progestogens. It
is a progesterone-dependent condition.
Diffuse or localized non-painful firm swellings of one or more mammary glands
will be present. No necrosis or inflammation is present histologically. As
hypertrophy mimics mammary neoplasia which is usually malignant, biopsy is
indicated.
Treat by removing the progesterone source, with OHE in diestrus animals and
cessation of exogenous progestogen therapy in other animals. The mammary glands
usually regress spontaneously if left untreated. Testosterone cypionate (0.5
to 1.0 mg/kg IM once) causes a decrease in milk production and may hasten
regression of mammary hypertrophy (not approved).
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- Mammary neoplasia
This is the third most common tumor of the cat (skin #1, lymphatics #2). Malignant
adenocarcinoma is the most common type.
Presentation - This is seen in older cats. They will present with firm nodular
masses in one or more mammae, unrelated to the time of last estrus. Tumor
incidence is equally common in all mammary glands.
To view a gross pathologic
image of feline mammary neoplasia, click here.
Metastasis to regional LN may or may not be palpable. Metastasis to many tissues
may occur; the most common cause of death is respiratory dysfunction secondary
to pulmonary metastases.
Due to its highly malignant character, biopsy is always indicated. Needle
aspirates may not be diagnostic. It is usually best to submit tissue after
surgical excision of the mass. Radical surgery, compared to lumpectomy, has
not been shown to increase overall survival time, but will decrease incidence
of local recurrence. Prognosis is associated with tumor size; following surgery,
the median survival for cats with tumors > 3 cm in diameter is 6 months,
for cats with tumors 2 to 3 cm in diameter 2 years, and for cats with tumors
< 2 cm in diameter approximately 3 years. Patients with pulmonary metastatic
disease rarely survive longer than 2 months after diagnosis.
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- Pyometra
Pyometra is most common in cats > 6 years of age.
The underlying lesion is CEH, which develops secondary to repeated exposure
of the endometrium to progesterone. Pyometra develops due to ascending infection
with normal flora of the vagina (most common are E. coli, b-hemolytic
Strep sp.). Pyometra may occur in cats receiving exogenous progestogens.
Diagnosis - Pyometra is easily diagnosed by identification of an enlarged
uterus in a non-pregnant animal. You may or may not see purulent to sanguinous
vulvar discharge. Systemic signs (e.g. PU/PD) are less common than in the
dog.
Treatment :
* OHE + fluids + antibiotics - This is the best option!
* PGF-2a + fluids + antibiotics. As in the bitch,
treatment may not promote endometrial repair to a significant extent. Queens
with CEH will always be predisposed to pyometra.
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- Male cats
Cryptorchidism - Cryptorchidism is less common
in the cat than in the dog. Heritability is unknown in the cat, as is predisposition
to torsion and neoplasia.
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