The average dog goes into heat twice yearly, although normal dogs may cycle
as frequently as every 5 months or as infrequently as every 12 months. When
a dog is in heat, she exhibits swelling of the vulva and exudation of bloody
to straw-colored vaginal discharge for up to three weeks. Male dogs are interested
in her throughout this time, but the average dog does not allow the male to
mount and breed her until she has been showing signs of heat for about 9 days.
The female allows breeding for about another 9 days. The average bitch is most
fertile from days 8 through 15 of heat, counting day 1 as the first day vaginal
bleeding was noticed. Many dogs may be successfully bred by introducing the
female to the male when she has been in heat about 7 days, and allowing breeding
every other day while the female allows the male to mount and the male is interested.
Many fertile dogs are not average dogs; female dogs may become pregnant from breedings well before or well after they ovulate, or release eggs from the ovary. Your veterinarian can help pinpoint your dog's most fertile time by assessing cells collected from the vagina with a swab or by measuring a hormone, progesterone, in blood. This increased accuracy in determining the female dog's fertile window is necessary when breeding with chilled extended or frozen semen. Click here for more information about ovulation timing in dogs.
Some breeders may wish to breed dogs that are geographically distant. It is difficult and expensive to ship dogs. Shipping refrigerated canine semen may be a better alternative in some cases. Accurate breeding management, to pinpoint day of ovulation in the female dog, must be performed. Optimally, insemination is performed twice, two and four days after ovulation; two separate shipments are required. Semen is collected from the male dog by a veterinarian, placed in a liquid medium called an extender, that nourishes, buffers and protects the spermatozoa in the sample, chilled to refrigerator temperature, and shipped. It is desirable for the semen to be inseminated into the female dog as soon as possible after collection. Shipment may be made counter-to-counter via a commercial airline or using an overnight service such as Federal Express or UPS. Kits for this procedure are not maintained at the University of Minnesota, but can be ordered directly by the breeder either from Synbiotics or Camelot Farms.
We do not freeze canine semen at the University of Minnesota. Please contact either Dr. Fran Smith (Smith Veterinary Hospital, phone 952-736-8278), Dr. Jim Winsor (Inver Grove Heights Animal Hospital, 651-451-4404) or Dr. Don Rice (Stillwater Veterinary Clinic, 651-439-3200).
Dogs may be bred accidentally, or may get away from the owner when they are in heat with subsequent possible breeding. The average female dog is most fertile when she has been in heat about a week, and remains fertile for about another week. Several options exist for pregnancy termination.
Ovariohysterectomy (OHE) - Ovariohysterectomy is spaying. Pregnancy is terminated by physical removal of the ovaries and uterus. This is a successful and permanent contraceptive technique. Your veterinarian may not be comfortable spaying your dog when she is in an advanced stage of pregnancy, so please contact them as soon as possible after the accidental breeding. This is the preferred method of pregnancy termination in dogs that are not specifically intended for breeding.
"Mismate" shot = Estrogen - Estrogen injections terminate pregnancy by altering movement of the fertilized egg(s) into the uterus. For estrogen shots to be effective, they must be given after the dog has released eggs from the ovary (evidenced by concentration of progesterone in blood greater than 4-10 ng/ml) but before she goes out of heat (evidenced by assessment of vaginal cells on a swab). If the shot is given before she ovulates, it will not work. If the shot is given after she has gone out of heat, there is a relatively increased risk of inducing uterine disease (pyometra). We do not administer estrogen mismate shots at the University of Minnesota Veterinary Teaching Hospital.
Prostaglandin - Prostaglandins are a class of hormones that are
naturally released in dogs at the end of their heat cycle. Prostaglandin F2alpha
is the drug most commonly used for pregnancy termination in dogs. It terminates
pregnancy by stopping production of the hormone progesterone, which is required
for pregnancy maintenance, and by causing uterine contractions, which physically
break down the pregnancy. Prostaglandin F2alpha can be used safely throughout
pregnancy, allowing us to definitively diagnose the dog as pregnant before any
medication need be given. Pregnancy diagnosis should be done one month after
the accidental breeding. If the dog is not pregnant at that time, nothing need
be done. If she is pregnant, prostaglandin F2alpha can be administered twice
daily for four days. At this point of pregnancy, the pups will be reabsorbed,
not aborted. Side-effects of the drug are short-lived, and include vomiting
and salivation. Prostaglandin F2alpha is the drug preferred
for pregnancy termination in dogs at the University of Minnesota Veterinary
Teaching Hospital
Dogs may develop vaginitis as puppies (puppy or juvenile vaginitis) or as adults. Underlying causes of vaginitis that have been identified include urinary tract infection or anatomical abnormalities within the vagina. Many cases of vaginitis have no apparent cause. The main clinical sign is vaginal discharge, which may look like mucous, blood, or pus. If the discharge is not excessive and the bitch is not bothered by it, no treatment is necessary. If an underlying cause can be idenitified, that should be corrected. Culture of the vagina and treatment with an appropriate antibiotic for at least one month may be helpful. Refractory cases may require long-term, low-dose antibiotic therapy, or concurrent treatment with an estrogen (diethylstilbestrol [DES], as used for urinary incontinence) or corticosteroid. These drugs are not recommended for use in dogs with juvenile (puppy) vaginitis. Dogs with juvenile vaginitis may benefit from being allowed to go through one heat cycle.
WHY SPAY-NEUTER YOUR PET?
We strongly recommend that all animals that are not going to be used for breeding be spayed or neutered. There are millions of dogs and cats euthanized in humane societies every year in the United States. Only those animals that are genetically superior should be bred. Some recent articles advocate spaying or neutering when animals are over one year of age, or not spaying or neutering at all. Some studies document increased incidence of some cancers in spayed and neutered dogs compared to intact dogs. However, the incidence of these disorders is still so low that it cannot outweigh the great benefits of these procedures, described below.
FEMALES
Female dogs and cats are spayed. Spaying is ovariohysterectomy, surgical removal of both ovaries and the uterus. This prevents the animal from coming into heat and from getting pregnant. The surgery can be performed safely anytime from 7 weeks of age in cats and 3 months of age in dogs. The benefits of spaying are:
- The animal will no longer be fertile.
- The animals will not go into heat, which is associated with bloody vulvar discharge in dogs and specific, usually undersirable behaviors in both dogs and cats.
- Animals spayed before they go through their first heat are at greatly decreased risk of developing mammary cancer late in life.
The disadvantages of spaying are:
- Immediately after surgery, hemorrhage may occur into the abdomen or the suture line may come apart. These side-effects are uncommon and usually are readily repaired by your veterinarian.
- Spayed dogs and cats may be predisposed to obesity. This can be controlled with proper diet and exercise.
- Spayed dogs may develop urinary incontinence, in which they leak urine where they lie resting or sleeping. This can be controlled with medication.
MALES
Neutering is the term commonly used to describe surgical reproduction control in male dogs and cats. The surgery is more correctly called castration, which is removal of both testes. The surgery can be performed safely anytime after 7 weeks of age in dogs and cats. The benefits of castration are:
- The animal will no longer be fertile. This is especially important in male animals for population control, since a single male animal can produce many more offspring than can a single female animal.
- Castrated male dogs are less likely to develop prostate disease with age.
- Castrated male cats are less aggressive, have less foul-smelling urine, and are much less likely to spray urine.
- Castrated male dogs are less likely to roam or to mount other animals or humans.
The disadvantages of castration are:
- Immediately after surgery, hemorrhage may occur into the scrotal sac. This side-effect is uncommon and usually is readily repaired by your veterinarian.
- Castrated dogs and cats may be predisposed to obesity. This can be controlled with proper diet and exercise.
Questions? Please contact Dr. Peggy Root by phone (612-624-7290) or email (rootk001@umn.edu).