18 February 2000

Combat foot-rot in hot spells

DRY, hot weather when the foot-rot organism is inactive is the best time to rid your flock of the disease.

It is an onerous task, admitted sheep vet Chris Lewis at a joint MAFF/ADAS meeting. But he reckoned a concerted, structured effort to eradicate it would take less time than bringing sheep in and out when they had feet problems during the year.

For best results, Dr Lewis suggested dividing flocks in two; lame sheep and those with good feet. "This means examining hooves of every sheep. You cant leave one because half the ewes walking soundly will have lesions."

Any sheep with lesions should be split off into a hospital group. It is important to ensure that those infected cant reinfect the main flock, and it was easier to treat 50 ewes than 400, he said.

The main flock should stand in 10% zinc sulphate solution mixed with a suitable wetting agent, such as washing-up detergent, for 20 minutes. When this was not practical you could use 3% formalin solution, he added.

Despite some concerns over formalin it was the best product to treat scald, said Mr Lewis. "But it must be mixed at 3% max, which is three pints of formalin to 12gal of water." But he recommended using zinc sulphate for treating foot-rot.

Then move the main group to clean grazing, free from sheep for at least 12 days. This group should be gathered again 10 days later, and the exercise repeated. If any sheep are lame they should join the hospital group, leaving a nucleus of foot-rot-free sheep.

"Infected sheep should be turned, their feet pared and an antibiotic injection given." He normally recommends using either 10cc of streptopen or long-acting oxytetracycline at 20mg/kg of sheep bodyweight.

Then footbathe infected ewes in a 10% zinc sulphate solution. "This is kinder on sore tissue than formalin. You must not use formalin, as this is far too painful." Once treated they should be returned to clean pasture.

This must be repeated five days later and again five days after that, but return any sheep that have recovered to the main flock after footbathing. The rest must be treated with antibiotics and footbathing before being put on to clean pasture once more.

After footbathing infected sheep five times, at five-day intervals, lame ones must be culled. "They are a danger to the rest of the flock and could reinfect them unless culled."

FOOT TREATMENTS

&#8226 Use antibiotics for foot-rot.

&#8226 Footbathe in 10% zinc sulphate.

&#8226 For scald use 3% formalin.