Last week when I had my veterinarian out to pull blood for a Coggins test on Bailey, I also had him give her all the shots she will need for this spring, including a Strangles vaccine which is needed for the stay at Benvelle.
Strangles, which is also called equine distemper, is a highly contagious disease which isn't necessarily fatal but can be long, drawn-out and unpleasant to deal with. It is caused by the bacteria Streptococcus equi and is spread through nasal discharge and pus from the abscesses that form. The first signs of the disease – fever, loss of appetite, cough and a clear nasal discharge – usually develop within two to six days after exposure, but it is also not uncommon for the incubation period to last 2 weeks.
As the disease progresses, the lymph nodes under the jaw and the guttural pouches become swollen, sometimes blocking the horse’s airway, which gives the disease its name of “strangles.” These swollen lymph nodes can become quite large and painful and they eventually burst and drain. The pus that drains from the abscesses is very contagious.
Horses can spread the disease to others through nose-to-nose contact, coughing, sneezing and snorting, and it can also be spread through contaminated buckets, bedding, clothing, tack and hands. Contrary to what some people may think, the strangles bacteria does not infect an area for life, but it can survive in an environment for up to a couple of months. Although they are no longer showing signs of the disease, horses are able to spread the infection for up to six weeks after they have been infected. These recovering horses are quite often the source of infection for others.
Intramuscular and intranasal vaccines are both available for Streptococcus equi. Getting a horse ready to accept the intranasal Strangles vaccine is helpful for your vet since it's the most commonly used method of vaccination. It is not true that once a horse has had strangles they are immune for life. This may be true for about 5 years, but then that immunity lessens over time. Also, vaccination does not guarantee protection against the disease, but it will lessen the severity and duration and helps to control outbreaks.
To try and keep Strangles from infecting an area, it would be a good idea to isolate new horses for four to six weeks before introducing a new horse to the herd, although sometimes that is a difficult thing to do. If a horse does become infected, he should immediately be isolated and then the disinfection of stalls, water and feed buckets, and other equipment will help to prevent the spread of the disease. Also keep in mind that the person taking care of the sick animal can spread Strangles through their boots, clothes and hands. As with any infectious disease, the first line of defense is effective handwashing.