4 June 1999

Hot tips to treat scald

Scald in lambs is difficult to treat, so what can sheep

producers do to ease the workload of footbathing ewes

and lambs regularly and achieve effective treatment?

James Garner reports

SCALD is like a blister, it looks innocuous but is excruciatingly painful for affected sheep and is particularly hard to treat.

Infected lambs are more frequently seen at this time of year. Scald, which is probably one of the most painful foot conditions, means that some lambs struggle to walk, says vet and foot specialist at the Royal Vet College Rose Grogono-Thomas.

Sheep producers hate seeing their stock hobbling with foot problems, and scald can be the worst offender.

"Scald is caused by a bacteria that lives in the soil and animal dung. It is present on every farm and in theory every sheep is exposed to it."

In practice what normally occurs is that certain conditions combine to allow the bacteria to invade the skin between the digits of the sheeps foot.

"Often it is wet weather and long, coarse herbage, particularly Italian ryegrass, that runs between the claws and abrades the skin.

"Once the skin is damaged the bacteria invades and causes scald." Its called scald because it looks like skin thats been damaged by boiling water.

Its a common condition in sheep. According to a Royal Vet College survey, 50% of flockmasters confirm that their flocks regularly suffer from scald.

It is aggressive and effects all breeds, says Mrs Grogono-Thomas. "It is probably seen more in terminal sire breeds, because their heavier weight puts more stress on their feet, which is more likely to precipitate scald."

Lambs are more commonly infected than ewes, perhaps because their feet are tender and the inter-digital space is closer to the ground, she says.

Unlike foot-rot where the knowledge exists to control and prevent the disease, scald is unpreventable because its in the soil and environment, making it difficult to treat. "When there are only a few lame animals it may be best to treat infected feet with an antibiotic spray."

Obviously this is not practical when there are many infected sheep and regular footbathing is the next best option, she says.

Diluted formalin or zinc sulphate will both cure scald. Formalin must be diluted to 1-3% and zinc to 5%. But beware strong formalin solutions can cause scald by damaging feet.

Formalin is normally bought as 40% solution, so it needs to be diluted at three litres of formalin to 100 litres of water to be at the correct strength. "Often it is used at 10%, which is far too strong for curing scald and too strong for foot-rot as well."

The longer sheep take to pass through the bath and the wider it is, the better. Also letting sheep, whether ewes or lambs, stand afterwards to let their feet dry is best where practical.

"It is a time consuming job. But it does reduce lamb growth rates and can also effect ewe performance."

Putting 5cm (2in) of ordinary sponge or foam in the bath, may make it easier to treat lambs. The animals seem to run through easier which makes it a less stressful experience, she adds.

SCALD

&#8226 Painful condition.

&#8226 Footbath lambs.

&#8226 Use dilute formalin.