Isolation of mycoplasmas from the genital tract of horses.

Vaginal swabs from 19 mares and penile swabs from 4 stallions were cultured for mycoplasmas. A single semen sample from one of the stallions was also examined. Twelve vaginal swabs and 2 penile swabs yielded mycoplasmas. Ten of the positive vaginal swabs were from mares with vaginitis, or with a history of failure of conception. Two were from apparently healthy mares, but one had been served by an infected stallion. One positive penile swab was from a stallion with ulcerative lesions and the other from a stallion with breeding difficulties. All 14 strains of mycoplasma utilised arginine, and the growth of 11 strains was inhibited by hyperimmune serum against one strain.