Animal Behavior for Shelter Veterinarians and Staff. Группа авторов
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Instead of the female moving away, she will stand in a braced position with her back feet base wide and deviate her tail to the side if touched near her vulva. If the male is inexperienced, the female may mount him, or she may actively solicit the male by backing into him with her tail flagged to the side. An estrus bitch will urinate a small amount frequently, similar to a dog with a UTI. Dogs have a tremendous sense of smell, and the hormonal changes in the female’s urine attract males over a large area (Bradshaw and Nott 1995). This results in the intact male roaming in search of the female.
The proestrus and estrus stages can last anywhere from a couple of days to four weeks. Behaviorally, diestrus is the first day the female is no longer receptive to the male. The vulva decreases in size, and the female may display aggressive threats as she defends herself from males. The diestrus period is the time from ovulation to either parturition or anestrus.
Initially, there are very few behavioral changes between a gravid and non‐pregnant female. During the last two weeks of gestation, the pregnant bitch’s abdomen starts to enlarge, her nipples and mammary glands continue to develop, and, at times, milk may even leak from her glands. She may prefer to eat smaller portions and may also be polydipsic and polyphagic. The enlarged uterus filled with growing feti places increasingly greater pressure on the stomach. Small frequent meals allow the bitch to ingest enough nutrients to support herself and the growing feti and to produce milk. Milk production also requires an increase in water consumption. The enlarging mammary glands may cause discomfort, resulting in increased licking of the uncomfortable area. Depending on the size of her litter and her body condition, she may also move more slowly. The change in hormones that occur during impending parturition may result in some bitches becoming anorectic and having looser feces. This may result in an evacuated gastrointestinal system, allowing for a more sanitary birthing process because general abdominal pressure may result in fecal expulsion.
Bitches, whether bred or not, may build a nest and act pregnant. Some will become very destructive in their nest building and dig up or destroy bedding, furniture, or other household items. In addition, they may also drag items from other parts of the house or yard to construct their nest. Some bitches will regard certain toys or objects as puppies and bring them to the nest. Others may carry the “pup” around with them. Some individuals may become very protective of their “surrogate litter.”
Parturition occurs approximately 63 days after ovulation. Plasma progesterone drops to less than 2 ng/dl (Concannon et al. 1978), followed 10–14 hours later by a drop in rectal temperature. Twenty‐four hours prior to parturition, many bitches’ rectal temperature drops below 100° F for a short period of time and then returns to normal. During this time, the bitch may seem restless and uncomfortable, pant, and nest build. These behaviors may also occur intermittently during the last week or two prior to parturition, with an increase in frequency as parturition becomes imminent.
Anestrus is the time from parturition until the next estrus cycle. During this time, a bitch’s behavior should be similar to that of a spayed female or unneutered male.
4.8.1.1 Pseudopregnancy (Pseudocyesis, False Pregnancy)
After estrus, the uterus undergoes the same changes whether the bitch is bred or open. Pseudopregnancy is just as it sounds. The bitch is in diestrus, and her body acts as though it is pregnant even though she is not. As described above, she may build a nest, become protective of toys, and exhibit mammary development. She may become restless, irritable, and/or lethargic. She may undergo contractions and have a liquid discharge. Pseudopregnancy is self‐limiting and generally does not require treatment. If treatment is necessary, the type will depend on many factors: gonadal status of the dog, duration and severity of signs, and the types of signs (physical or behavioral). Treatment regimens have not been well described, and more research is needed on this problem.
Pseudopregnancy can occur in any breed and has been known to occur in bitches as young as 7 months of age and those as old as 10 years of age (Johnston 1986). The incidence of pseudopregnancy is unknown but estimated to be as high as 50–75% by one author (Johnston 1980). In a survey study in the United Kingdom, veterinarians reported seeing 10 cases per year on average (Root et al. 2018). Of greatest concern, 96% reported behavioral changes in these patients without noteworthy physical changes, and 97% reported aggression as one of the behavioral signs (Root et al. 2018). Pseudopregnancy may occur in a gonadectomized bitch three to four days after her ovariohysterectomy (Johnston 1986) if the surgery was performed during the diestrus phase of her cycle and not the anestrus phase. The implications of this, combined with the data from the Root study, should not be ignored. Collecting a vaginal swab for cytology is not difficult or time‐consuming, and many resources exist for aiding in the analysis. Vaginal cytology is routinely used for determining stage of estrous. Performing ovariohysterectomy on female dogs in the shelter without knowing their stage of estrous could result in behavioral changes that are hormonally related. Similarly, if aggression is seen in a recently spayed female with an unknown history, an awareness that it could be related to hormonal changes may affect behavior assessments and any planned interventions, including behavior modification.
4.8.1.2 Mastitis
Mastitis is an infection of the mammary glands seen most commonly in intact bitches post‐parturition or post‐pseudopregnancy. In most cases, it is not a life‐threatening condition and generally only affects one or two glands. The bitch is typically pacing and restless, lying down and getting back up. She will often lick and/or chew the infected gland. The infected gland appears enlarged, firm, and erythematous, and it is likely painful to the touch. Suckling by the puppies may elicit an aggressive response, such as growling, lip lifting, snapping, or biting. The bitch may also move away from the puppies and avoid staying with them, as nursing is painful. This leaves the puppies hungry, so they initially cry more, but if they are not fed, they become lethargic, their cries become weaker, and their suckle response decreases.
4.8.1.3 Eclampsia
Eclampsia is an acute condition of the pregnant bitch where the blood levels of calcium fall to dangerously low levels. This hypocalcemic condition may occur pre‐ or postpartum and is most often seen in small breeds, although it can occur in any breed. Initial signs include restlessness, whining, and pacing that progresses to a stiff gait. The signs progress very quickly to lateral recumbency with extensor rigidity and impending death without treatment (Pathan et al. 2011). Upon physical exam, the bitch is generally hyperthermic due to muscle rigidity.
4.8.1.4 Metritis
Metritis is an infection of the uterus postpartum. Bitches with metritis are thin, lethargic, and have a purulent vaginal discharge. Initially, the bitch may spend an excessive amount of time licking and grooming the vulvar area. As the disease progresses, she may not feel well enough to expend the energy to clean herself. Often, the bitch will become anorectic, and because of the decreased caloric intake, her milk production may decrease. This will result in increased vocalization of the puppies, whose nutritional needs are not met. Any dog with puppies that suddenly begins avoiding her pups or acting aggressively toward them should be thoroughly examined for eclampsia, mastitis, and metritis, as her change in behavior may be a result of pain and discomfort.
4.8.1.5 Pyometra
Pyometra is an infection of the uterus that occurs when the uterus is under the influence of progesterone (Nelson and Feldman 1986). It is common in intact female dogs, but actual risk has been difficult to confirm in North America due to the high incidence of gonadectomy. Pyometra should be viewed as an important risk to the intact female dog.
Typical signs of pyometra include polydipsia and weight loss. Many bitches show depression, a slightly decreased appetite, increased panting (likely due to endotoxemia and their febrile state), and lethargy. Others may seem relatively normal except for polydipsia and excessive licking or grooming of the perineum and hindquarters. They may also have urinary “accidents” in the house; this is generally secondary to polydipsia and pressure on the bladder from the increased size of the uterus.
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