Update on the CEM debate

Breed societies remain unhappy with the testing requirements for contagious equine metritis (CEM), despite these having been relaxed somewhat, says Dr Mac.

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In May 2016, the department of agriculture (DAFF) relaxed the requirements for testing breeding stallions for the venereal disease, contagious equine metritis (CEM).

The new regulations now allow for a single test that will be valid for two years, instead of the annual two tests at seven-day intervals originally required. A test currently costs R200. However, as the swabs must be taken by a vet, breeders in remote areas often have to pay the vet’s travel expenses.

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The Arab Horse and Boerperd breed societies, which each have a large number of members, have long objected to the fact that the tests are mandatory only for registered breeders. The latter cannot register foals unless the stallion is negative. The dispute has not been resolved by the relaxed requirements.

CEM poses a danger in that it could threaten the export of racehorses, warmbloods and endurance horses. For this reason, CEM is a notifiable disease, but the tests are not subsidised in any way by DAFF.

Stopping a CEM outbreak

Breeders should understand that the most cost-effective way to stop an outbreak is through stallion testing. Stud breeders face the greatest risk from CEM, as a carrier stallion can infect up to 40 visiting mares in a season. The disease is then widely spread when the mares return to their owners.

An infected breeding operation can lose about 30% of foals due to early resorption and chronically infected mares becoming infertile.

Treatment is very expensive and not always successful. The Animal Diseases Act currently specifies that positive mares should be euthanised and stallions castrated.

Although DAFF could allow state vets to take samples, most are used to working with livestock and are not particularly keen to take penile swabs from stallions. Stallions may need to be tranquillised intravenously and state vets do not have access to these drugs.

On the other hand, stud owners usually own horseboxes and travel to shows or endurance rides. It would not be impossible for them to take a stallion to an equine veterinary practice to reduce costs.

Another option is for a breed society to contract a vet to take samples in each province and subsidise the transport costs for its members.

Whatever the case, the risk of CEM justifies the testing costs involved. As mentioned, a good breeding stallion can serve 40 horses a season; if the service fee is only R2 000, that comes to R80 000.

The test, plus vet fees, usually comes to slightly less than R1 000, although breeders have claimed it can be up to R5 000 due to travel costs.

The cost remains a good investment, though, if you consider that a 30% loss of R80 000 is R24 000. If you also take into account the potential cost of valuable breeding stock becoming infertile or being culled, it is worth the expense, particularly as testing has now been reduced to two-year intervals.

The risk of CEM is also decreasing, as no further infected stallions have been found. It is likely that, in future, the test will be required only if breeders want to sell chilled or frozen semen.

Dr Mac is an academic, a practising equine veterinarian and a stud owner.