Strangles is an infectious bacterial disease in horses caused by the bacterium Streptococcus equi equi. It is characterised by an acute upper respiratory infection and swollen or abscessed lymph nodes around the head and neck. Strangles is normally a disease of young horses but any horse that hasn’t been vaccinated or hasn’t been exposed to strangles before can be affected.
How does it spread?
The bacteria are spread by direct contact with nasal discharge or pus from infected lymph nodes. So, nose to nose contact can cause the disease to spread but it may also spread via indirect contact with infected material that the sick horse has been in contact with e.g. bedding, yards, tack, clothing, troughs etc.
What does the disease look like and what do I need to look out for?
The time from when a horse is exposed to strangles to when it gets sick (incubation period) is approximately 3-6 days but on rare occasions it can take up to 14 days to develop. The earliest clinical signs you see are fever (up to 410C), lack of appetite, and nasal discharge that may be clear or pussy. As the disease progresses the lymph nodes under the jaw and neck will swell and may abscess and need draining.
Can Strangles be life threatening?
Strangles doesn’t normally cause death but it can make your horse very sick through complications and can spread rapidly through other exposed unvaccinated horses.
What do I do if my horse might have been exposed to strangles?
Its very important to keep you horse isolated from other horses. If it has been running with a group of horses, then these should be kept isolated as a group. Once a horse has clinical signs it can be infectious for around 4 weeks. If you suspect your horse may be developing clinical signs please call your vet. Diagnosis can be made on clinical symptoms or nasal swabs. If you have Strangles diagnosed it is very important that you do not transport your horse around the district as this will increase the chance of the disease spreading.
Keeping good hygiene is critical so cleaning areas and equipment exposed to strangles with a disinfectant such as Virkon is recommended.
Vaccinating horses against strangles is the best way to manage this disease risk. The vaccination program consists of three sensitiser doses 2 weeks apart then yearly or six-monthly booster doses depending on the risk.
Unfortunately, horses that have been recently exposed to Strangles and may be incubating the disease should not be vaccinated as vaccination in the face of an outbreak can cause a disease called pupura haemorrhagica which can be worse than Strangles itself. Get in touch with your vet for more information.
Alex Meban (BVSc)