What is Strangles in Horses?

What is Strangles in Horses?

Strangles is a highly contagious bacterial respiratory disease of horses that can spread rapidly through stables, agistment properties, training facilities and groups of horses. Whilst such a definition sounds alarming, the good news is that Strangles is a disease we can significantly reduce the risk of through vaccination, good biosecurity and early identification.  

So, what exactly is strangles and why should horse owners take it seriously? 

Strangles is caused by the bacterium Streptococcus equi subspecies equi. The bacteria primarily infects the horse’s upper respiratory tract and associated lymph nodes. It is highly contagious and can be transmitted through direct contact with an infected horse or indirectly through contaminated equipment and surfaces. This can include the likes of shared water troughs and buckets, feed bins, halters, bits and lead ropes, tack and grooming equipment, floats and trucks, stable surfaces,  people’s hands, clothing and footwear. This is why one case can quickly become a much bigger problem on a property! 

What are the signs of strangles? 

The term strangles comes from severe cases where swelling around the throat can interfere with normal swallowing and, occasionally, breathing. As these lymph nodes enlarge, they can become extremely painful and may eventually rupture and discharge pus. 

Clinical signs can vary, but affected horses commonly develop: 

• Fever & high temperatures; often one of the earliest signs 

• Depression and lethargy 

• Reduced appetite 

• Thick nasal discharge 

• Coughing 

• Pain or difficulty swallowing 

• Swollen lymph nodes beneath the jaw and around the throat 

• Abscess formation within affected lymph nodes 

Most uncomplicated cases recover with appropriate veterinary management, but strangles should never be dismissed as simply a nasty cold. Complications can develop rapidly, and lead to severe implications. One of the better-known severities is “bastard strangles”, where infection and abscesses develop in lymph nodes or organs elsewhere in the body. Another potential complication is purpura haemorrhagica, an immune-mediated condition that can result in inflammation of blood vessels and significant swelling. 

Whilst horses can make a full recovery, they can become carriers, harbouring the bacteria within the guttural pouches without appearing unwell. These horses can potentially become a source of infection for other horses, even though clinical signs are no longer present. 

What should I do if I suspect strangles? 

If your horse develops fever, nasal discharge or swollen lymph nodes, contact your veterinarian and isolate the horse immediately. 

Until your veterinarian has assessed the situation: 

• Don’t move the horse off the property. 

• Keep them separated from other horses. 

• Don’t share buckets, tack or grooming equipment. 

• Allocate separate equipment to the affected horse. 

• Wash your hands thoroughly after handling them. 

• Change or disinfect contaminated clothing and footwear. 

• Avoid moving between sick and healthy horses unnecessarily. 

• Take temperatures of potentially exposed horses as directed by your veterinarian. 

Biosecurity is incredibly important when dealing with infectious equine disease. Australian government guidance recommends measures including isolating new horses, monitoring their health and maintaining good hygiene and cleaning practices. 

Reporting requirements can also vary between Australian states and territories. For example, strangles is currently a notifiable disease in Victoria. 

Can I vaccinate against strangles? 

Yes, you can vaccinate for Strangles! 

Strangles vaccination can substantially reduce the risk and severity of disease, although no vaccine can guarantee that an individual horse will never become infected.  

Vaccination is particularly worth discussing with your veterinarian if your horse travels regularly, lives at an agistment property, attends shows, clinics, camps or clubs, regularly encounters unfamiliar horses, and/or lives on a property where horses frequently arrive and leave. 

Your veterinarian can recommend an appropriate initial vaccination course and ongoing booster schedule based on your horse’s age, previous vaccination history and exposure risk. 

What other preventative measures can I take? 

A strangles outbreak can mean weeks of isolation, veterinary treatment, cancelled competitions, restricted horse movements and considerable disruption to an entire property. 

Some simple preventative measures can make a big difference: 

• Keep vaccinations up to date. 

• Quarantine new arrivals before introducing them to resident horses. 

• Avoid sharing water buckets at events. 

• Don’t allow horses to share feed bins. 

• Clean and disinfect floats and equipment regularly. 

• Monitor horses closely after travelling or competing. 

• Know your horse’s normal temperature. 

• Isolate horses immediately if they become unwell. 

Strangles may be highly contagious, but it is also a disease where we have practical tools to significantly reduce the risk. Talk to your veterinarian about your horse’s strangles vaccination status, particularly if it’s been a while since you last checked the vaccination record.