Pregnancy Determination in Goats

Pregnancy detection in does is commonly performed using real-time ultrasonography to visualize the presence of an embryo/fetus and/or placentomes within the uterus.

Transabdominal ultrasonography is quick and reliable and can detect pregnancy as early as 30 days, though it is most accurate after 45 days' gestation (1). If possible, does should be fasted from food (12 hours) and water (4 hours) to improve speed and accuracy when performing ultrasonography in large herds.

Transrectal ultrasound is more difficult and time-consuming, although it can diagnose pregnancy as early as 20 days. Ultrasonography can be used to count embryos/fetuses most accurately up to 85 days' gestation, which is important when managing does prone to pregnancy toxemia in late gestation (see twin pregnancy ultrasonography image).

Twin pregnancy, goat (ultrasonography)

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Diagnosis of a twin pregnancy using transrectal ultrasonography at 37 days' gestation in a goat.

Courtesy of Dr. Jamie Stewart.

Fetal sexing may be performed by skilled ultrasonographers between days 55 and 70 of gestation and is more accurate in singles versus multiples. Radiography can be used to detect pregnancy with 100% accuracy after day 70 and can detect the number of kids after day 75, though it is not routinely performed because of impracticality and cost.

Progesterone concentrations can be measured in milk or serum. However, this method is not recommended due to low accuracy. Samples must be collected precisely one cycle (19–24 days) after the doe is bred.

Whereas low progesterone levels can confirm that a doe is not pregnant, high progesterone is not a positive pregnancy test, because it cannot differentiate between midcycle, true pregnancy, or pseudopregnancy.

Progesterone concentrations cannot accurately determine viability or predict fetal number when performed early in pregnancy. Tests can also be expensive to perform in larger herds.

A commercially available blood test can reliably detect pregnancy as early as 25 days after breeding in goats. This kit tests for the presence of pregnancy-specific protein B (PSPB), also known as pregnancy-associated glycoprotein, which is produced by the placenta. Owners may choose to submit this test themselves after observing nonreturn to estrus in bred does.

An animal-side SNAP test is also available that will test for the presence of PSPB. Compared with ultrasonography, this blood test is not as accurate for counting fetuses or determining fetal viability.

Concentrations of PSPB are reportedly lower in does carrying singletons versus multiples (2). Therefore, grouping does by PSPB levels may be useful when managing late gestation. However, because of the long half-life of PSPB, false positives may occur when fetal death has occurred within the last 15 days. Therefore, ultrasonography is still considered the gold standard for pregnancy detection.

Hydrometra, or pseudopregnancy, is well documented in goats, although its cause is largely unknown. Aseptic fluid accumulates within the uterus and is accompanied by high peripheral concentrations of progesterone due to a failure of luteolysis (see pseudopregnancy vs pregnancy image).

Pseudopregnancy vs pregnancy, goat

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Left: A fluid-filled uterus is visible on ultrasonographic evaluation of the abdomen. However, no cardinal signs of pregnancy are evident, consistent with hydrometra (or pseudopregnancy). Right: Both an embryo (within its amniotic vesicle) and a placentome are observed with ultrasonography, consistent with pregnancy.

Courtesy of Dr. Jamie Stewart.

Approximately 50% of pseudopregnancies are thought to result from early embryonic death at ≤ 40 days of gestation. An additional mechanism involves spontaneous persistence of the corpus luteum, which occurs more commonly in older goats or in does bred out of the natural breeding season or after induced ovulation. The diagnosis can be made by excluding pregnancy coupled with the presence of clinical signs.

Hydrometra can be treated with prostaglandin to lyse the corpus luteum, and does may be able to conceive again if diagnosed and treated early. However, if the condition persists or recurs, the chances of future conception decline, and does should be culled. Other reported causes of hydrometra in older does include cervical adhesions that develop after a dystocia and prevent normal drainage of fluid or neoplasia. These animals will not respond to prostaglandin administration and have a poor prognosis for fertility.

Abortions in goat herds are relatively common and have severe economic implications. Diagnostic evaluations should be performed when abortions exceed 5% of the total number of pregnant animals in a herd or if several does abort within a short period of time.

Chlamydiosis (Chlamydia psittaci), toxoplasmosis (Toxoplasma gondii), campylobacteriosis (Campylobacter fetus fetus), and Q fever (Coxiella burnetii) are commonly identified infectious causes of goat abortions in the US. Placental lesions are commonly observed with these pathogens due to the development of placentitis.

If congenital defects, such as arthrogryposis, are observed, then viruses (eg, Cache Valley fever, border disease, bluetongue) and toxic plants (eg, Veratrum californicum) should be suspected. The fetus and placenta should both be submitted to a diagnostic laboratory. Paired serum samples should be obtained from the doe and stored appropriately, in case serology is indicated. A thorough history, including nutrition and any recent changes in husbandry, should be taken to aid in diagnostic evaluation and management.

Prevention of abortions and prevention of infertility are best achieved by maintaining low-stress herds and implementing appropriate biosecurity measures. New animals should be isolated for 2–3 weeks before introducing them to the herd.

Vaccinations against Chlamydia and Campylobacter spp may be incorporated into herd health protocols if necessary. However, these vaccinations only minimize losses and do not completely prevent infections.

Though previous strategies to reduce likelihood of abortions involved the prophylactic administration of feed-grade tetracyclines, this practice had minimal efficacy and is now restricted with the implementation of the veterinary feed directive.