Strangles.
Streptococcus equi
Strangles is a highly contagious bacterial infection of the respiratory system in horses.
It is spread by direct contact between horses, contact with infected material in the environment or from people.
Symptoms
- fever over 38.5°C
- depression
- lack of appetite
- thick mucus nasal discharge
- abscesses on the sides of head and throat, causing discomfort eating or extending the head
Healthy adult horses may experience short-term mild symptoms or none at all, meaning they often go unnoticed.
Complications are rare but can be serious.
- ‘Bastard’ strangles where abscesses from in other areas of the body.
- Purpura haemorrhagica causing damage to blood vessels of the body.
Treatment & Recovery
Affected animals should be isolated immediately, with strict biosecurity measures implemented.
Most horses recover with good nursing care and anti-inflammatories, with horses being encouraged to eat from the floor. Hot poulticing abscesses can encourage them to rupture. Antibiotic use is controversial and most cases do not need them.
The incubation period is up to 14 days, however abscesses can develop up to 21 days. Following recovery a guttural pouch wash or 3 nasopharyngeal swabs at weekly intervals should be performed to confirm resolution.
Previously infected horses are still at risk of infection in the future, previous infection does not provide future protection!
Prevention and Screening
New arrivals to yards should be kept quarantined for 3 weeks prior to entry with equipment and personnel not be shared between isolated horses and other horses on the establishment.
An ELISA blood test to assess antibody levels and establish exposure status in horses prior to entry into a new yard may be useful and should be performed 1 week before entry onto the main yard.
Carriers
Around 1 in 10 horses can remain carriers despite appearing fully recovered.
The bacteria hide in the guttural pouches at the back of the throat and the horse can intermittently shed bacteria into the environment posing an ongoing risk to other horses.