FAQ

The estrous cycle of the bitch consists of proestrus, estrus, diestrus, and anestrus. Proestrus is the first stage of heat, and she will exhibit a swollen vulva and have moderate bleeding. Male dogs are interested but she does not allow mounting. Estrus, or standing heat, is characterized by receptivity of the bitch to a male, and the vaginal discharge is frequently yellowish rather than bloody. Diestrus and anestrus are the stages of the cycle after ovulation, during which there are no characteristic physical changes. The average bitch cycles about twice a year. Proestrus and estrus are each generally 7 10 days, for a total length of heat of about 3 weeks, but can range from 1-6 weeks. Prime fertility is during the very end of the heat.

Optimal breeding day is 2 to 4 days after ovulation in bitches. Ovulation is determined by measuring the hormone progesterone. Progesterone does not cause ovulation; luteinizing hormone (LH) from the pituitary stimulates ovulation in dogs and other species. A significant rise and fall in serum concentration of LH, which lasts at most 24 hours, occurs 2 days before ovulation. Bitches undergo a process called preovulatory luteinization, in which the lining of the ovarian follicles containing the eggs begin to secrete progesterone prior to ovulation, and occurs in a linear fashion, allowing us to use progesterone as an indicator of the LH peak and ovulation.

The progesterone test can be done every 2-3 days starting on day 5 of heat. The beginning progesterone levels are typically less than 1.0 ng/ml until the day before the LH surge. The day of the LH spike, progesterone concentrations are 2-3 ng/ml; and progesterone tends to double each day after. Ovulation occurs between 5 and 10 ng/ml. It is important to continue testing until ovulation is confirmed, as split heats, or anovulatory heats, can occur.

Do not try to pull dogs apart! When dogs are tied, the engorged proximal portion of the penis is caught within the muscular lips of the vulva and pulling the dogs apart is extremely painful and very dangerous to them. The male has already ejaculated at this point, so the bitch is not less likely to become pregnant even if you did pull them apart.

For pregnancy termination, an initial determination of likelihood of pregnancy having occurred is warranted. It has been reported that only about 2/3 of dogs presenting for pregnancy termination are pregnant, as ties frequently occur before the fertile period. However, healthy dog sperm can live for up to a week in the reproductive tract of normal female dogs. To determine pregnancy, an ultrasound is performed 30 days post mating. If she is pregnant, there are several safe options available. Ovariohysterectomy, or a spay, is the safest and quickest option. If the bitch is to remain intact, a prostaglandin called Estrumate is used to decrease progesterone below the levels required to maintain pregnancy, and to cause uterine contractions and evacuation. Minor side effects include cramping and GI upset, but this method is overall very safe, and future fertility is maintained.

There are several types of artificial inseminations (AI), which vary by anatomic location. Vaginal AI is performed by inserting a pipette in the vaginal vault, several inches before the cervix. Intrauterine inseminations preclude the sperm having to “swim” through the cervix, and enable the sperm to be deposited directly into the uterine horn. There are two types of intrauterine inseminations — surgical and transcervical. For a surgical AI, the dog is put under anesthesia, an abdominal incision is made, and the sperm is injected into the uterus. For a transcervical insemination (TCI), the bitch is awake and standing, and a rigid endoscope is passed through the cervix into the uterus, and sperm is deposited into the uterine horn via a catheter. This procedure is the gold standard for breeding, and it is minimally invasive, and highly accurate.

Fresh semen is used during natural matings, or side by side breedings, where the stud dog is collected, and the ejaculate is used right away for insemination. Chilled semen is fresh semen that undergoes an extending process to stabilize it for shipment and use within 48 hours. Chilled semen can be shipped across the country, or even internationally. Frozen semen is semen which undergoes a cryopreservation process and is stored in liquid nitrogen for use anytime in the future. Frozen semen may be shipped anywhere in the world and stored, but it is the most fragile, with a lifespan of only about 12 hours once thawed for use. Because of this, intrauterine insemination is required for frozen semen breedings.

There is no early pregnancy test for dogs and cats. Embryos are visible on ultrasound at around 25 days post breeding, and most ultrasounds are performed at around 30 days. Ultrasound is excellent for determining pregnancy, but is only about 50% accurate to count number of puppies. For an accurate puppy count, an x-ray is performed in the last 10 days of gestation when skeletons are fully formed and calcified. This is recommended in bitches who are free whelping at home, so owners can monitor delivery of all fetuses.

False pregnancy, or pseudopregnancy, occurs because the hormone progesterone is elevated for 2 months after a heat, whether the bitch is pregnant or not. The bitch may gain weight, have mammary gland development, even lactate, and exhibit nesting behaviors. Symptoms resolve after 65 days, when hormones return to baseline. Imaging is recommended to confirm lack of pregnancy.

Normal gestational length is 63-65 days post LH surge. In dogs, the fetuses initiate onset of labor, so bitches carrying only one pup or carrying dead pups may not spontaneously enter labor. Progesterone concentrations fall abruptly in the last 1-2 days of gestation, leading to a decrease in body temperature, typically to <98F. Owners are recommended to start taking rectal temperatures 2-3x daily in the last week of gestation to monitor for this trend.

Labor occurs in three stages. In stage I, the bitch is restless and panting, exhibits nesting behavior, and typically declines food. No abdominal contractions are visible. This stage may last as long as 12 hours. The second stage is passage of puppies. Puppies may be born either head first or rear end first with limbs extended and may be within the amniotic sac when born. From the first obvious abdominal contractions, a pup should be born within 4 hours. No more than 2 hours should elapse between pups. Dystocia is the term for an interrupted labor where complications occur. Puppies may be malpositioned and block the birth canal, or uterine intertia may occur, where the muscles run out of energy and stop contracting. Green fluid without the passage of a puppy, or significant hemorrhage can indicate life threatening complications. Third stage labor is passage of the placentas and usually occurs along with second stage labor, with the bitch passing a puppy and then the placenta shortly after. Bitches frequently eat the placentas, which may cause GI upset, but is otherwise of no consequence. Puppies should be nursing within an hour of birth. First time mothers may require strict supervision and assistance. Puppies should be feeding every 2 hours for the first 4 weeks of life. At this point, they can transition to gruel made of high quality puppy food, and can become more independent.

Puppies are under the influence of maternal antibodies until they are about 8 weeks of age. For this reason, early vaccines are ineffective. First puppy vaccines should be received at about 8 weeks of age, and they should have boosters every 4 weeks for a total of 3-4 sets. Core puppy vaccines consist of distemper, parvovirus, adenovirus and parainfluenza. Parvovirus and distemper and both highly contagious diseases that have very high mortality rates. These viruses can be in the ground, in the air, on toys, benches, or even shoes. Puppies are not safe until they have had at least 3 sets of vaccines timed appropriately. For this reason, do not take puppies to public areas such as dog parks, pet stores, grooming parlors, or even on walks around the neighborhood, until they are fully vaccinated. IF your puppy shows any signs of illness, such as vomiting, diarrhea, or lethargy, please have your puppy examined right away.

Signs of heat, such as vocalizing, lordosis, and receptivity to toms, is not normal in a spayed female, but is not uncommon. Typically these signs are consistent with ovarian remnant syndrome, a condition where ovarian tissue (which may be located abnormally) is left inadvertently during the spay surgery. Have your cat examined when she is showing signs of heat. Exploratory surgery to locate the remnants may be scheduled at that time. Medical suppression of estrous may be possible but is not recommended for this syndrome.