Strangles is an upper respiratory tract infection, caused by the bacterium streptococcus equi. It is highly contagious spreading easily between horses, ponies and donkeys.
Risk factors
Young horses between the age of one and five are most susceptible. Others at risk include those that are in poor body condition or have a high parasitic burden. Any yards where there is movement of horses on and off the premises are at a high risk of bringing strangles on to the yard.
Transmission
Direct indirect
- Contact with infected horse
Indirect
- Food and water bowls
- Grooms hands and clothes who has had contact with infected horse
- Shared tack and grooming kit
- The yard dog
- Nasal excretions in the environment from infected horse
- Pus from ruptured abscess in the environment
Clinical signs
- High temperature 41⁰C
- Moist cough
- Depressed and no appetite
- Abscesses in the throat region
- Nasal discharge
- Swelling in throat region
- Difficulty swallowing, painful
Clinical signs are generally not apparent until two to six days after infection but can take up to 14 days to become apparent. Abscesses usually form in the lymph nodes around the throat region and are seen as prominent swellings which can make swallowing and breathing difficult. These abscesses will rupture 10 to 14 days after the onset of clinical signs.
In up to 20% of cases, abscesses can form in lymph nodes in other parts of the body such as the lungs, liver, spleen, kidney and brain. These cases are known as bastard strangles and have a poor prognosis of recovery.
10% of horses become carriers of the bacteria and will not show any signs of infection but have the potential to infect any other horse that they come into contact with.
Treatment
If you suspect strangles, isolate the affected horse immediately. Ideally this should be in a completely different shed where there is no contact with other horses or donkeys. Once isolated please contact us for advice since treatment varies depending on the stage of the disease.
If abscesses are already apparent
- Avoid treatment with antibiotics since this can slow down the development of the abscesses and prolong the disease.
- Apply hot packs around the throat to enhance the maturation of abscesses.
- Give anti-inflammatories to relieve pain and reduce associated inflammation.
- Feed soft palatable feeds as this is easier to swallow.
- Keep the horse rested and warm. Good nursing care is essential.
If no clinical signs are apparent but had contact with infected case
- Monitor temperature and demeanour daily. If temperature rises antibiotics should be administered.
- Keep separate from infected case.
Movement of all horses on and off the premises should be stopped. Infected horses should be barrier nursed with a separate groom hand ideally dealing with the infected cases so as not to spread bacteria. Food and water bowls should not be moved between infected and non-infected cases and separate tack and grooming kits should be used. All bedding from the infected cases should be burned and the box and tack disinfected.
To definitively diagnose a case of strangles swabs need to be taken from the nasopharynx and sent to the laboratory. Blood samples and analysis of the pus from ruptured abscesses can also be useful. Endoscopic exam of the guttural pouches can also be useful as pus can accumulate here causing the horse to become a carrier of the disease. By examining the guttural pouches we can then flush the pus out, aiding recovery.
Prevention
- Isolate all new arrivals for one month, watch for clinical signs and monitor rectal temperature once daily. If they develop nasal discharge, temperature spikes or throat swellings are apparent then it should be tested for infection with strangles.
- A vaccine Equilis Strep E is available against streptococcs equi which can be used to reduce clinical signs of the disease in the face of an outbreak. It needs to be given every three to six months and is injected in to the gum. Please contact us for further advice.
