What exactly is Strangles?

Zoe Satsias BVM&S MRCVS, St David’s Equine Practice

Every horse owner dreads the word ‘Strangles’ being mentioned by their vet. We all know that a diagnosis is serious… but what exactly IS Strangles?

Strangles is one of the most common equine diseases worldwide. It is caused by infection with the bacterium Streptococcus equi, and is primarily a disease of the upper respiratory tract. It is spread by direct contact, which is why biosecurity is key in controlling an outbreak on a yard. Strangles is potentially devastating and can cause fatalities, this is why symptoms and diagnosis must be taken very seriously.

Typical clinical signs of disease include:

Fever

Loss of appetite

Depression

Marked ‘snotty’ nasal discharge (this is the most common sign)

Lymph node swelling and abscesses, predominantly of the head and neck

Remember that not all horses will show all (or any) of these signs! This is the danger of Strangles. Some horses can be carriers of the disease and, subsequently, spread the disease to other horses unknowingly. The bacteria sits in the carrier’s guttural pouch (sacs at the back of the throat) and is occasionally shed and passed on to in-contact horses. Once diagnosed, the guttural pouches can be medicated and the horse will be confirmed free of Strangles after timely treatment.

Diagnosis of disease

In order to confirm Strangles, your vet will need to take a nasopharyngeal swab from your horse. This is a very long swab that goes up your horse’s nostril and to the back of its throat where the bacterium is most likely to reside. A blood sample will also be taken, this will tell your vet whether your horse has been infected, whether it is a carrier or whether it has been exposed to Strangles in the past. Other methods of diagnosis include culturing pus from affected lymph nodes or from nasal discharge. The incubation period is between 3-14 days, with abscesses forming up to two weeks later.

Complications

Strangles can become deadly by spreading to other parts of the body and forming abscesses, which subsequently rupture. This is called ‘Bastard Strangles’. Another complication is a rare bleeding disorder, called Purpura haemorrhagica, which can also be fatal to your horse.

What to do in an outbreak: If your horse or a horse on your yard has been diagnosed with Strangles, the first thing to do is isolate the affected horse.

The yard must be closed to horses leaving and entering the premises.

Monitor all horses on the yard by taking rectal temperatures twice daily.

Divide horses into three groups: a red group – horses infected or with raised temperatures, an amber group – horses that have had direct contact with infected horses but are showing no clinical signs and a green group – horses that have had no contact with orange or red group horses and appear healthy.

Avoid mixing equipment and tack. Use gloves and overalls when handling infected horses and wear waterproof shoes that can be dipped in an appropriate disinfectant between the groups.

An outbreak can unfortunately close down a yard, and can last for months.

Prevention

There is a vaccine available that helps the control of Strangles. If interested, please contact your vet for further information. Vaccination should always be used in conjunction with good stable management and disease awareness.

It is easy to follow some simple steps to help prevent disease:

When away from home with your horse: Do not mix equipment. Use your own water and feed buckets. Wash your hands after handling other horses. Disinfect your boots before you get back home.

All new horses should be isolated for three weeks on entry into a new yard. A blood test should be taken at the start and at the end of the three weeks to check for exposure to Strangles.

Use separate equipment for each horse on your yard at home.

Awareness and taking action without delay are key in helping to control Strangles. These websites provide some useful information www.aht.org.uk/strangles and www.equine-strangles.co.uk

St David’s Equine provides the equine veterinary services for Molecare in the South Molton, Newton Abbot and Cullompton areas. Visit www.stdavids-equine.co.uk for more information.