Measurement of IgG concentration in ovine fetal fluids: a useful diagnostic test.

The Veterinary Diagnostic Laboratory at Oregon State University received 172 aborted ovine fetuses during the 1985-1987 lambing seasons; from 120 of these, body fluids were evaluated for IgG levels. Fifty-two (43%) of the fetal fluids had immunoglobulin G (IgG) levels greater than 15 mg/dl. Forty-five (87%) of the fluids with elevated IgG levels were confirmed or presumed toxoplasma or chlamydia abortions. A mean fetal fluid IgG concentration of 111.5 +/- 78 mg/dl was found for the 26 toxoplasma abortions; for the 19 chlamydia abortions, a mean IgG concentration of 109 +/- 91 mg/dl was found. Antibody titers equal to or greater than 1:40 against Toxoplasma gondii were detected in 23 fetal fluids. Fetal fluid IgG concentration less than 15 mg/dl was found to be associated with bacterial organisms (i.e., Campylobacter sp.) as the confirmed or presumed cause of abortion. These results suggest that measurement of fetal fluid IgG concentration is a useful, supportive diagnostic test in determining the cause of ovine abortion, and should be included as a routine laboratory procedure for ovine abortion diagnosis.