Strangles is a very common but unpleasant bacterial disease that can affect horses, ponies and even donkeys. Signs vary between individuals and can range from very mild to dramatic in appearance. Strangles is a disease caused by bacteria called Streptococcus equi subspecies equi (Strep. equi) and is highly contagious being spread by direct contact with infected discharges or with contaminated clothing or equipment. Horses can also be silent carriers of the bacteria displaying no outward signs but being capable of infecting others.
Clinical Signs of Strangles in Horses
Clinical signs of strangles in horses are split into two types:
- Classical signs of fever include: loss of appetite, depression, cough, thick nasal discharge and pain, swelling and abscess formation in the lymph nodes under the jaw and in the throat region are most commonly seen in younger horses;
- Milder signs include: short term fever, dullness, loss of appetite and mild nasal discharge
Milder signs of strangles are increasingly common and may be evidence of a previous or ongoing infection.
Some cases can have serious complications:
Some cases of strangles can have serious complications for horses, this is why you’ll want to catch the disease early before it gets a hold of the horse. Sadly, for some horses, strangles can have a more serious effect than others no matter how early you diagnose the problem.
- “bastard” strangles is caused by the spread of bacteria and abscess formation in different areas of body
- Purpura haemorrhagica is inflammation of the blood vessels with fluid swelling (oedema) of the limbs
You may also see small areas of bleeding or bruising on the mucous membranes of the gumsand eyes.
Up to 10% of horses may recover and appear normal but remain infected. These horses are ‘silent carriers’ harbouring the bacteria in the guttural pouches of the throat; they can infect other horses.
Diagnosis of strangles in horses can be difficult and may require multiple tests. These will be done by your vet at the earlies convience. ANY horse or pony suspected to have strangles should be moved and isolated using the correct biosecurity measures.
The diagnosis procedure includes:
- bacterial detection on nasopharyngeal (nose and throat) swabs, guttural pouch washes and fluid collected from an abscess
- blood test for raised or rising antibodies
- carriers of strangles can be detected using a screening blood test and guttural pouch wash (flushing and collecting fluid from the pouches in the throat)
Key Take-Away Points
Key points to remember out the disease include:
- highly infectious
- highly debilitating
- affects all equines of all ages
- takes a long time to treat
- some horses can become silent carriers of the bacteria after infection
Nursing care is the mainstay of treatment for horses with strangles, which involves:
- damp/sloppy foods to aid swallowing
- warm packs/poultices to help the abscess mature and cleaning and flushing to speed their resolution
- anti-inflammatories to make the patient feel more comfortable
- Antibiotic use is controversial and may delay abscess bursting and increase the risk of complications (cases should be individually assessed)
- following recovery, a guttural pouch wash should be performed to confirm resolution of the disease.
Prevention of Strangles in Horses
Strict biosecurity policies include:
- quarantine new horses for three weeks prior to entry to the yard;
- new horses should have a clear blood test in the week preceding entry onto the main yard;
- routine screening blood tests of horses to identify carriers. When an outbreak is confirmed or strongly suspected:
- close the yard to prevent horses from leaving or entering and alert all visitors to the yard;
- institute the protocol for dealing with an outbreak of infectious disease;
- isolate infected animals and all that have been in contact;
- clean and disinfect all equipment;
- unless the source is clear, investigation should be carried out to identify and treat carriers of the disease
- Notify local yards in the area and any necessary bodies
A vaccine is available in the UK that reduces the severity of signs use may be recommended in some yards following a specific risk assessment.
In Association with XLEquine – Picture of Health, where prevention is better than cure
For a downloadable fact sheet visit xlvets-equine – strangles