8 March 1996

Irish, north &south, take brunt of EAE

ENZOOTIC abortion of ewes (EAE) is particularly marked in Northern Ireland and Eire this year, says Dr Gareth Jones of the Moredun Institute, Edinburgh.

When ewes do succumb to the disease, which costs the UK sheep industry about £15m a year, they will abort in the last four weeks of pregnancy, at about 135 days. "You might start to see a dirty discharge which has a characteristic putrid smell," explains Dr Jones.

"The placenta will show characteristic lesions and pussy tissue. It goes a dirty red or brown and is a major source of infection."

Afterbirth should be disposed of immediately. It can be buried and not become a future source of infection. The site of infection must be disinfected thoroughly.

Injecting with long-acting tetracycline, at the recommended dose, is the most efficient way of stemming spread of infection to ewes yet to lamb. "But you can only inject the rest of the flock between 95 and 115 days into gestation because the bacteria are not detectable and causing damage on the placenta until 95 days. After 115 days the damage to the placenta is severe enough to be irreversible," says Dr Jones.

If used properly he believes it is possible to "risk" just one injection. However, trials at Moredun show that injecting ewes again 14 days later reduced EAE incidence to 0.5% compared with 2.5% with just one injection.

"Justifying the second injection means measuring the cost and bother against a perceived decrease in abortions," he says.

EAE can only be diagnosed by lab examination of the aborted lambs.