Just hearing the word Strangles is enough to make any horse owner shudder. Strangles is present in New Zealand, and cases are seen in the Manawatu. A good understanding of the disease will lessen the worry and panic often associated with strangles.
What is strangles?
Strangles is a worldwide infectious disease of horses caused by the bacterium Streptococcus equi equi. It is characterized by an acute upper respiratory infection and lymph node abscessation. It is primarily a disease of the young but horses of any age without previous infection or immunization may be affected.
How is it transmitted?
The bacteria are passed on by direct exposure of infected nasal discharge as well as the pus from abscessed infected lymph nodes. This means that transmission may be direct from horse to horse but also indirectly from contaminated bedding, boxes, grooming gear, water troughs, horse floats, gumboots, quad bikes, fence railings and the list goes on!!! It is therefore important that areas that have come into contact with the infected horse are sanitised with a disinfectant, e.g. Virkon, to help prevent further spread. It is also possible that recovered horses can become carriers.
What are the signs to look out for?
The incubation period for strangles is between 3-6 days. Early clinical signs include a fever, up to 41 0C, a decreased appetite and a clear to pussy bilateral nasal discharge. As the disease progresses the lymph nodes of the head and neck become swollen and eventually abscessation of the lymph nodes will be seen. Once abscesses have matured and drained, the normal course of disease will take 10-14 days to resolve. Diagnosis can be made on clinical signs and/or a nasal swab and/or pus from draining lymph nodes.
Is it a fatal disease?
Strangles is rarely fatal but it can make horses very sick and because it is very contagious a lot of horses can become sick within a short space of time. Occasionally complications (pneumonia, further abscesses within the body, to name a couple) can arise so it is important to keep in touch with your vet regarding the horse's progress.
How do I prevent it spreading?
To prevent spreading between horses on your property, isolate the infected horse so there is no fenceline contact. If the horse has already been running with a mob of horses then that group can be isolated together. It is also important to disinfect yourself between handling different horses.
Care must be taken when introducing naïve horses to recently infected horses because affected animals are infectious for more than 4 weeks after onset of clinical signs.
If you have had strangles diagnosed on your property, please do not transport your horses as this will increase the chances of spreading the disease around the country.
Can we vaccinate?
There is a good vaccine available. The programme consists of three vaccinations two weeks apart, followed by a yearly booster. Boosters can be given six-monthly in high risk situations. Please talk to your vet if you would like to begin this programme
We do not recommend vaccination in the face of an outbreak or if your horse has been in contact with a strangles horse. By vaccinating a horse that may be incubating strangles, a disease called pupura haemorrhagica can develop which can have devastating consequences for the horse so please talk to your vet for advice on this.