Reproductive difficulties in cattle with antibody titers to Haemophilus somnus.

A herd of Holstein cows was examined because of suspected embryonic death. Four cows had embryonic loss, and 2 cows had aborted. Paired serum samples were tested for antibodies to infectious bovine rhinotracheitis virus, bovine viral diarrhea virus, and Haemophilus somnus. Of 16 cows, 8 had antibody titers to H somnus greater than 1:1,024, and 3 had greater than or equal to four-fold changes in antibody titers to H somnus. Haemophilus somnus infection was active in this herd and may have been responsible for the herd's reproductive problems.