Real-time ultrasonography used for cattle, sheep, and horses is accurate with a skilled operator; however, equipment is expensive. Scanners are best used between 40 and 90 days of pregnancy, and multiple pregnancies are diagnosed with 95% accuracy. Routine radiography can be used with 100% accuracy after day 70 and can detect the number of kids after day 75.
The progesterone test can be done on milk or serum, but samples must be collected precisely 1 cycle after the animal was bred. The progesterone test is good at detecting nonpregnancy but is not a positive pregnancy test because it cannot differentiate between midcycle, true pregnancy, or false pregnancy. The estrone sulfate test, performed on milk or urine, can determine pregnancy. Between 40 and 50 days after conception, the level of estrone sulfate increases substantially and stays increased throughout pregnancy. Abortion, fetal death, or resorption causes the estrone sulfate level to drop; therefore, the test also is a useful measure of fetal viability. Pregnancy specific protein B is also produced by the placenta and can be detected in serum or plasma by ELISA performed at least 30 days after breeding.
Precocious milking is common in heavy-milking strains of goats. It can be seen in a virgin doe or during the first pregnancy. Therefore, udder development is no guarantee of pregnancy.
False pregnancy is a problem in dairy goats. It can be shorter or longer than a true pregnancy. Usually, the udder enlarges, but true filling does not occur. The doe may show behavioral signs of impending parturition; she may even call or search for the nonexistent kid. Many of these does conceive the next year, but many are dried off and are economic losses for 1 yr.
Last full review/revision July 2011 by Joan S. Bowen, DVM