Biosecurity

Mark Tabachnik graduated from the Royal (Dick) School of Veterinary Studies in 1995 and, in 2016, became the chairman of XL Equine, a collaborative group of more than 100 equine vets who aim to be the quality mark for equine care.

A new horse at our yard has had strangles in the past. Is there a risk he could still be carrying it, and what signs do I need to watch out for? Daisy Grier, Carlisle A Once a strangles infection has cleared the horse should be clear of the disease. However, a small proportion of horses become carriers. In these cases, the bacteria that causes strangles lives within the guttural pouch and can’t be attacked by the immune system. The guttural pouch is part of a small tube at the back of the horse’s throat called the eustachian tube. Bacteria within this pouch will intermittently be shed by the horse through nasal discharge, but very often carriers actually don’t show any visible signs at all, and the horse will appear to be healthy. In the acute stages of the disease horses can show obvious signs of strangles, such as a snotty nose, cough or generally being listless. They may also have swollen lymph nodes under their chins or around their jaws. Horses with clinical signs of strangles should be isolated to prevent the spread of infection, and under the care of their vet.

Carrier horses

The key to managing strangles is to identify carrier horses, and blood samples are helpful in determining this. A blood test called a strangles ELISA will identify whether a horse has had, or still has, strangles. Ideally a horse should have this blood test before being moved onto a new yard. If there is any doubt whether infection is present, vets can use endoscopes to examine the guttural pouch and take samples of any fluid for analysis. It’s a good idea to have an isolation facility for new arrivals, as signs of infection often don’t appear for several days. This is known as the incubation period and it might last as long as 14 days. Isolating a horse for three weeks is a good amount of time to see if he’s carrying any diseases. You may wish to then re-blood test to check he remains clear.

Making isolation work

Isolation facilities can be simple; it requires an area that isn’t in the same airspace as other horses and where nose-to-nose contact isn’t possible. Provide separate buckets, barrows and feeders, and make sure people aren’t crossing from the isolation facility back into the yard without cleaning and disinfecting their boots and clothes. It’s a good idea for every yard to designate a quiet corner as an isolation facility, and apply a strict policy for new horses entering the group. (Turn to page eight for news of a possible vaccine.)