CHAPTER 1 Prenatal Care of the Bitch and Queen
Prenatal care for bitches and queens should begin with the selection of the most desirable members of a potential breeding population. The resources of the important registration bodies and the available databases for evaluation of inherited genetic diseases should be used to select desirable traits. Information is available from the American Kennel Club (AKC), the Cat Fanciers’ Association, the United Kennel Club, and many individual breed clubs. The most significant health database is maintained by the Orthopedic Foundation for Animals (OFA). The OFA is a private nonprofit foundation that serves as a central source of information for breeders and owners based on the standards for evaluation established by the experts in each discipline. The Canine Health Information Center (CHIC) is a joint venture of the OFA and the AKC Canine Health Foundation. The focus of CHIC is health consciousness; this focus allows breeders to manage breed-specific genetic disorders. The criteria for acceptance into the CHIC program are established by each of the parent clubs that are involved. Participation in any health database is voluntary but should be encouraged by practitioners (Box 1-1).
More than 400 genetic diseases have been recognized in the dog, and genetic diseases are responsible for 25% of all disease problems affecting dogs. With the exception of inherited renal dysplasia, all of the most commonly diagnosed inherited diseases are seen in mixed breed dogs. Designer dogs have the same prevalence of genetic disease as the purebred breeds. Responsible breeders of dogs and cats, as well as the respected breed registries, make great effort to improve the genetic health of their breeding animals and thus decrease the risk of avoidable inherited disease.
The various competitive venues available to breeders, such as conformation shows for cats and conformation shows, obedience competitions, agility competitions, hunting tests, and field trials for dogs, offer layers of selection in the choice of reproducing animals. Certainly, not every bitch or queen is worthy of reproduction and the practitioner should encourage and educate potential breeders on their responsibility to choose healthy, quality bitches and queens for their breeding programs.
Breeding dogs or cats involves tremendous commitment of time, space, knowledge, and financial resources. The practitioner should counsel prospective breeders regarding the ethical considerations involved in breeding, including the difficulty in placing puppies and kittens in permanent homes and the responsibility incurred in creating these new lives.
Bitches selected for breeding should be mature enough to have genetic clearances for their appropriate breed and young enough to produce reasonable litter size and survivability. A bitch is at her peak reproductive potential between 2 and 4 years of age. In at least one study of beagle bitches, conception failure occurred in more than 50% of bitches 5 years of age or older. Similarly, the risk of dystocia increases, neonatal mortality increases, and litter size decreases with increasing maternal age. Average litter size is known for most purebred breeds, with average neonatal losses approaching 30%.
The bitch should be presented to the clinician during proestrus of the anticipated breeding cycle. A complete physical examination should include a rectal examination to evaluate the bony pelvis and a digital vaginal examination to detect any vaginal abnormalities. Brucella canis serology using the rapid-slide agglutination test should be done. An in-house test is available (D-Tec CB, Synbiotics; www.synbiotics.com); this test has high sensitivity and low specificity. Any positive result requires additional testing and should cause a delay in breeding during the cycle in which test results are confirmed. Regardless of previous breeding history, all bitches should be evaluated because the disease is spread orally, as well as venereally. Serologic testing for canine herpes virus should be performed on virgin bitches or in bitches with a previously negative test. If the bitch has a negative titer, she must be protected from exposure to the virus. More detailed information pertaining to herpes virus can be found in Chapter 16.
Isolation from other canids for 3 weeks before whelping to 3 weeks after whelping should prevent disease. There is no vaccine available in the United States. Vaginal cytology should be obtained and stained to assess the epithelial cells present. The bitch should either have her vaccinations brought up to date or have titers performed to assess her antibody levels. The bitch should be well protected against canine distemper and canine parvovirus to maximize maternal antibody levels.
The bitch has an endotheliochorial placenta. Puppies depend on mammary transfer of antibodies because placental transfer is minimal. With normal ingestion and absorption of colostrum, the antibody level of the puppy will approximate 95% of the dam’s measured antibody level. Gut permeability to immunoglobulins begins to decline within 8 hours after birth and is no longer possible after 48 to 72 hours.
The bitch should have baseline laboratory tests performed to assess her suitability for pregnancy and lactation. A bitch with total plasma protein levels of less than 5.0 gm/dl is unlikely to whelp a litter of strong, healthy puppies. Bitches with significant renal or hepatic dysfunction are not successful brood bitches. If the bitch has a history of infertility or pregnancy loss, a vaginal culture should be performed during the first 5 days of proestrus. Although the value of vaginal cultures is controversial, most clinicians consider a pure culture in significant numbers of a known pathogen to be worthy of treatment. The vaginal culture should be interpreted within the context of patient history, physical examination findings, and vaginal cytology. Both B. canis and Salmonella sp. are always considered pathogens. B. canis is rarely treated in any kennel or colony situation. In kennel situations, B. canis is managed in a test and cull manner because it is highly contagious and nearly impossible to eradicate with therapy. Antibiotic choice and duration of treatment should be based on safety and efficacy in pregnancy. Bitches that have sustained pregnancy loss may be monitored weekly for hypoluteoidism, which is a poorly documented condition.
During normal pregnancy, progesterone reaches peak levels of 15 to 90 ng/ml. During the last trimester of pregnancy, progesterone decreases until it drops below 2 ng/ml approximately 1 day before whelping. A progesterone level above 2 ng/ml is required for the maintenance of pregnancy in the bitch. If the progesterone drops to 10 ng/ml, frequent monitoring of the progesterone levels is recommended. Progesterone values of 5 ng/ml may warrant intervention with an exogenous progestogen supplementation. Exogenous progestogen administration is an extralabel use of any of the available preparations and should always be accompanied by careful client education and a signed release form outlining the risks. Prolactin and luteinizing hormone (LH) are also luteotrophic in the bitch.
The queen should also be examined before breeding. When presented, the queen should have a complete physical examination, including baseline laboratory work, and a fecal examination should be performed. Serology for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) should be obtained. Only queens testing negative for these two viruses should be used for breeding. Neonatal isoerythrolysis occurs in purebred cats. This condition may be avoided by blood typing the queen and breeding to a tom of an appropriate blood type (Box 1-2). The blood types of domestic felids are A, B, and AB. The breeds with the highest frequency of type B blood are the British Shorthair, the Devon Rex, and the Cornish Rex. Cats are unusual in that unlike dogs, they have naturally occurring antibodies to other blood types. The A allele (A) is dominant to the B (B) allele so only the cats with homozygous recessive condition (BB) express the type B antigen on their erythrocytes. Type A cats are either homozygous AA or heterozygous AB. The AB blood type is rare and inherited separately as a third allele recessive to A and co-dominant with B. Feline neonatal isoerythrolysis occurs when maternal anti-A alloantibody gains access to the fetal circulation after colostrum ingestion and destroys type A and type AB erythrocytes. Type A and type AB kittens from a type B queen bred to a type A or AB tom are at risk. Specifics pertaining to the clinical manifestations of the disease in neonates are discussed in Chapter 2.
In the case of breedings within catteries, the status of all cats with respect to feline coronavirus (FCOR) should be evaluated (Table 1-1). To prevent the spread of coronavirus, the tom and the queen should have the same serologic status. The Chlamydia status of cattery members should also be determined using serology.
|Infectious agent||Cats testing negative||Cats of same serology status|
FeLV, Feline leukemia virus; FIV, feline immunodeficiency virous; FCOR, feline coronavirus.
The queen should be vaccinated for feline panleukopenia (FPL), feline herpes virus (FHV), and feline calicivirus (FCV) to prevent clinical disease within the cattery (Table 1-2). However, vaccination alone may not prevent the spread of infection. Higher levels of maternal antibody may be achieved by boostering the vaccinations just before or at the time of breeding.
|Infectious agent||Vaccinate||Do not vaccinate|
FeLV, Feline leukemia virus; FIV, feline immunodeficiency virus; FPV, feline panleukopenia virus; FHV, feline herpes virus; FCV, feline calicivirus.
The queen has an endotheliochorial placenta. Colostral antibodies are the main source of immunoglobulins in the kitten. Progesterone produced by the corpus luteum is necessary for maintenance of pregnancy in the cat since placental production of progesterone is minor. The corpora lutea remains functional throughout pregnancy and regresses after delivery. The queen typically has a progesterone level of 1.0 to 1.6 ng/ml at day 60 of pregnancy. Thus pregnancy likely involves pregnancy-specific secretion of luteotrophic hormones of placental or pituitary origin. Several studies indicate that prolactin is a major luteotrophic factor in pregnant queens after implantation has occurred. Hypoluteoidism has not been reported in the queen. Progesterone therapy to prevent recurrent pregnancy loss should only be considered when infectious causes of pregnancy loss in the queen have been ruled out.
Proper diet for gestation begins before the bitch becomes pregnant. The bitch should be fed a quality, name-brand diet labeled complete for all life stages by the Association of American Feed Control Officials (AAFCO) standards using feeding trials or suitable for pregnancy and lactation. There is minimal need for increased calories during the first half of pregnancy. The bitch should be kept in fit condition, and her caloric intake should be appropriate to allow for a weight gain of approximately 36% over her normal prepregnancy weight. The diet should contain a protein level of 25% to 34% and a fat level of at least 18% with a balanced supply of n-6 and n-3 fatty acids, as well as optimum vitamins and minerals. Supplements should be avoided to prevent dietary imbalances and inadvertent toxicity.
Calcium supplementation is unnecessary and can result in decreased parathyroid hormone (PTH) stimulation of bone resorption. Eclampsia (puerperal hypocalcemia) can occur when the bitch depends on intestinal calcium absorption rather than on the PTH-stimulated bone calcium mobilization. After confirmation of pregnancy, the puppy or kitten diet is appropriate during the second half of pregnancy. Immediately after delivery, the bitch or queen should weigh approximately 5% more than her prepregnancy weight. It is nearly impossible to overfeed the bitch or queen during lactation. Recently, it has been established that nutrients may influence maternal or fetal gene expression, thereby influencing the metabolic status of an animal for life. It has been established that both prenatal and postnatal nutrition contribute to metabolic programming.
Many bitches experience a period of reduced appetite or inappetence during the second trimester of pregnancy. This period may be brief or prolonged. The bitch should be encouraged to eat by adding palatable foods to her diet (cooked meat or canned food). If inappetence persists, force feeding may be necessary.
Nutritional insufficiency of taurine may result in resorption, abortion, and stillbirth of kittens. Effects of a taurine deficient diet may persist beyond an individual lost pregnancy. This effect is unlikely to be seen in queens who are fed feline commercial diets but may be seen in situations where dog food is fed to cats. Dietary supplements are not recommended. Pregnant and nursing queens may have nutritional needs that are four times maintenance requirements. Canned foods may prove to be more palatable during pregnancy and should be offered if the queen’s appetite wanes.