The fight to keep bugs at bay
Published 16/08/2011 | 05:00
At a recent bout of sheep shearing on a lowland flock, the shearer complained about excess mites on his clippers blades.
The farmer was most upset by the shearer's comments as he had been vigilant this year in treating all his sheep.
In fact, the whole scenario resulted in a complaint to the drug company about how ineffective their product was.
The farm vet was called to investigate the affair, as this was a particularly well-run farm that prided itself on the production of premium product.
An injectible version of one of the ivermectin family of medicines had been used to good effect on the farm for several years. There was little or no wool loss and no signs of scratching. That is to say not until the middle of the grazing season.
Samples of wool and skin scrapings were taken and dispatched to the regional veterinary laboratory. But the answer was fairly obvious on initial clinical examinations on the first farm visit.
There are a range of skin parasites that affect sheep in the form of mites and lice. Some of the parasites burrow deeply into the skin and others live fairly much on the surface, eating dead flakes of skin and such like.
In years gone by we used dips to protect against sheep scab; a particularly nasty form of skin parasite on sheep.