by W.P. Howey

Contagious Equine Metritis CEM

Contagious Equine Metritis (CEM) aka ‘Jubilee Clap’

Contagious Equine Metritis (CEM) was first diagnosed in 1977 in the UK and spread to many countries, initially in thoroughbreds. Because the first diagnosis was made at the National Stud in Newmarket, Suffolk, UK in QE II’s Jubilee Year (25 years of Rule since Coronation) it was quickly dubbed ‘Jubilee Clap’ by the satirical pundits. The sobriquet stuck.

It was also identified in Australia in 1977, but since eradication in 1980, Australia has been free of the disease. Contagious Equine Metritis currently occurs in the United States of America, parts of Europe, South Africa and the United Arab Emirates.

I/we were intimately involved with the very first definitive diagnosis at a Stud on the outskirts of Scone in early spring 1977. The mare Opera had been ‘exposed’ in 1976 at another stud in southern NSW. It is certain the venereal disease had been introduced in 1976; perhaps even earlier? We will never know. A major innovative stud in South Australia was also implicated. However these farms were among the leaders of their generation. It was the very beginning of the now systemic ‘Shuttle Stallion’ scheme.

Unfortunately very shortly before we had in the Upper Hunter also ‘hosted’ the very first outbreak of Equine Herpes Viral Abortion (EHVI ‘Abortion Storm’) in Australia. This event preceded the initial diagnosis of the introduction of CEM. They were cataclysmic times. Ignorance, fear and chaos ruled. Pandemonium prevailed; briefly. It was very soon confirmed a valuable shuttle stallion from a major Irish Thoroughbred enterprise to a Widden Valley Stud Farm had ‘infected’ his first three mares by venereal transmission. The proverbial hit the fan. Fortuitously we had the in-house expertise to make the definitive diagnosis which requires specific laboratory agar plate culture (‘micro-aerophyllic incubation on chocolate blood agar for 48 hours’), bacterial isolation and identification.

I/we called a special meeting held in the Scone Bowling Club in July. The stud master on whose property the first Viral Abortion Storm was confirmed nobly allowed dissemination of the information. He said he could not risk his untarnished reputation in business. He was a rare individual in the thoroughbred world. This was just before the Hunter Valley Bloodhorse Breeders Association was formalized. It expedited the process. I chaired the meeting attended by over 400 delegates from all over Eastern Australia. Some had flown in by private charter aircraft from Victoria including AEVA President Geoff Hazzard. Most were anxious breeders with about 10% veterinarians. The NSW Government Veterinarians (Bruce Boots, Geoff Carter et al) acknowledged they ‘had no plan or expertise to deal with outbreaks of diseases in horses’. Nairn Fraser spoke on Viral Abortion strongly emphasizing it was caused by a VIRUS spread by droplet (‘nasal’) inhalation and/or ingestion. John Morgan elaborated on CEM labouring the fact it was caused by a BACTERIUM which was venereal in transmission. We thought at least that fact would be absorbed. It wasn’t. Considerable confusion reigned supreme. The reality is that the AEVA and veterinary practitioners ‘on the ground’ dealt with the outbreaks.

Contagious Equine Metritis is caused by the bacteria Taylorella equigenitalis. Horses are the only hosts. The disease was originally detected in thoroughbreds but is now rare. Cases still occur in warmblood and Arabian horses. The disease is spread by venereal transmission in both mares and stallions. Infection may also occur mechanically with poor hygiene when examining the genital tracts of mares and stallions.

Signs of contagious equine metritis

Signs include:

  • mares develop an inflamed vagina and thick, odourless discharge from their genital tract 1–3 days after mating, or sometimes later
  • there may be a lot of discharge or only an accumulation of grey or grey-white fluid in the vagina
  • discharge usually disappears after 3–4 weeks
  • mares may return to heat a few days after infection.

Stallions show no clinical signs and some infected mares show no signs. Test for CEM if mares show chronic infertility.

In the case of Viral Abortion the signs are just that; aborted foetuses (foals) in the third trimester of pregnancy. This will therefore be prevalent in mid-winter and/or early spring. Very soon after our initial diagnosis in Scone a large stud farm on the western outskirts of Sydney reported full term foals born normally but which very quickly developed serious respiratory disease unresponsive to treatment. Most died. This was soon confirmed as a ‘new clinical syndrome’ due to EHVI infection late in pregnancy. It added fuel to the fire of the rumour mill now in overdrive.

As in most things all eventually settled down. To be forewarned is to be forearmed. We were. CEM was eliminated within three years. Viral Abortion occasionally ‘flares up’ but is managed by a combination of strategic vaccination and good management practices. Hyperventilating stud farmers, mare owners and the omnipresent self-anointed polymath tribe of experts in the thoroughbred world settled down. Normality resumed as soon as was practicable.

This was one of the major challenges we faced in c. 50 years of veterinary practice in the Hunter Valley. I think we were equal to the task?