Memories of contagious equine metritis 1977 in Newmarket.

The research article discusses the outbreak of a new venereal disease among mares in 1977, its cause, diagnosis and treatment efforts, as well as its impacts on the overall fertility rates of affected populations.

Outbreak of a New Venereal Disease in Mares

• The research paper starts with an account of a significant occurrence of an unidentified venereal disease among mares in Newmarket in 1977. This ailment was characterized by increased purulent vulval discharge post-mating, recurring oestrus within 8 or 9 days, inflamed cervix, and signs of severe endometritis.
• The disease was first noted at the National Stud in Newmarket and in mares from other farms who had mated with the National Stud’s stallions. The disease showed no systemic signs in any horse, mare, or stallion and no significant growth was found through bacterial culture of the pus.

Identification and Transmission of the Causative Bacterium

• Throughout March 1977, similar symptoms were found in mares mated by stallions not from the National Stud, suggesting the disease was spreading through lateral transmission, possibly by veterinarians or handlers during preservice examination.
• The cause of the disease was found to be a bacterium named Taylorella equigenitalis. It was initially traced back to the clitoris, thereby improving the diagnosis and control of venereal diseases in mares and stallions.
• The origin of the disease remained mysterious until consultations with Irish colleagues revealed similar symptoms had been observed in some mares in Ireland the previous year. A number of mares visiting the National Stud stallions in 1977 during the outbreak were from Ireland, suggesting a potential link.

Debate and Impact on Fertility

• The difficulty in pinpointing a specific cause for the disease led to numerous debates. The National Stud and several other stud farms decided to cease covering mares due to damage risks.
• Despite the outbreak, many stud farms chose to continue covering as the clinical symptoms resolved with or without treatment. The fertility rate was affected, reducing from 86% in the previous year to 70%. The disease spread to 29 stud farms affecting 200-250 mares and 23 stallions.

Successful Culturing of the Bacterium

• In May 1977, swabs and pus samples were sent to Dr. Edward Taylor with experience of culturing for gonorrhoea. Successful culturing of the bacterium occurred over a long holiday weekend when the plates were left unexamined for four days, growing colonies similar to those seen in smears.
• The bacterium, sensitized to most common antibiotics including penicillin and nitrofurans, was resistant to streptomycin. This finding reduced contaminants when streptomycin was added to the culture medium.