Canine Lost Pregnancy: Diagnosis and Prevention

Establishing and maintaining pregnancy is dependent on many biological interactions between the embryo or fetus and the pregnant female. For approximately 12 days after fertilization, free-floating embryos are dependent on the fluid environment within the uterus for development. If this environment is inhospitable (due to inflammation, hormonal imbalances, infection etc.), embryos may not survive. Death of embryos during this period often goes unnoticed because the embryos are resorbed before pregnancy has been detected. Most embryonic losses occur during this period and at implantation, when attachment to the uterus first takes place. These losses are collectively referred to as early embryonic deaths. After implantation, embryos depend almost entirely on the dam and will not survive if she is unable to adjust to the physical requirements and demands of pregnancy. Factors that lower the odds for survival include fetal or maternal abnormalities, nutritional deficiencies, environmental stresses or infectious causes. Infectious agents are the most common cause of canine abortion.

A number of pathogens are associated with canine abortion. Brucella canis is most prevalent in kennel situations where contact with infective discharges and fetal tissues may result in infection and possible abortion in susceptible females. Infected males may spread the disease to noninfected females at breeding. Breeding kennels should routinely test all animals for B. canis. To date, there is no permanent cure for B. canis infection in the dog. Therefore, infected animals must not be bred again and should be removed from contact with other breeding animals.

Neospora caninum can infect the brain and spinal cord of developing fetuses or neonates. Newborns have progressive muscular weakness leading to death. Toxoplasma gondii is a protozoal parasite causing mild disease in adult dogs. It’s affects may be more severe when present with distemper virus, which is known to suppress the immune system. Fetal infection may occur and T.gondii has been found in the milk of lactating bitches. Mycoplasma and Ureaplasma species have been cultured from the cranial vagina and prepuce of healthy, fertile animals. However, when females are housed in crowded kennels, close contact and environmental conditions can lead to increased numbers of these organisms, resulting in infertility and pregnancy losses. Providing adequate space, a clean environment and separation of individual breeding animals will greatly reduce the risk of abortion resulting from these and other bacterial infections.

Canine distemper and adenoviruses may cause spontaneous abortion with or without fetal infection. Canine herpesvirus abortions have been associated with chronic infertility and cannot be effectively treated at present. Affected females should be isolated from susceptible pregnant animals. Viral abortions are most often due to the stress of clinical disease in the bitch. These can be prevented by routine vaccinations. Pregnant females should not be vaccinated with modified-live vaccines, as these could adversely affect fetal survival.

To control infectious causes of abortion, bitches should be vaccinated regularly and tested for potential abortion-related pathogens prior to breeding. HealthGene Laboratory is offering two problem-specific DNA profiles that include the combination of DNA tests for most common pathogens causing abortion in dogs: Canine Loss Pregnancy Profile (Brucella canis, Staphylococcus aureus, Sterptociccus spp, Mycoplasma spp., Ureaplasma spp., Canine herpesvirus, Chlamydophila spp.).

With any abortion, the bitch should be presented to a veterinarian as soon as possible for a complete physical examination and collection of samples for diagnostic testing. In most cases, these diagnostic procedures will not save the pregnancy, but they will help identify the appropriate supportive medical therapy and the management practices necessary to prevent future abortions. We recommended submitting a blood sample (EDTA tube) as well as a vaginal swab in a sterile container from bitches with the recent case of abortion or which will be used for the future breeding. Also, our laboratory recommends testing the sire that was used or will be used for breeding by submitting a blood as well as a semen sample. DNA tests on the semen can be done using our Canine Semen Profile (Brucella canis, Mycoplasma spp., Ureaplasma spp., Chlamydophila spp., Canine herpesvirus, Leptospira spp.)

One of the most important but often overlooked diagnostic procedures is the examination of the aborted fetuses and their associated membranes. In some cases, the bitch may consume aborted fetuses before they can be retrieved, but when these fetuses are available, they should be collected in as clean a manner as possible and taken to the veterinarian with the bitch. DNA testing of selected fetal tissues may be recommended.