Horse Strangles: Every Owner's Nightmare - Part OneBy Jeffrey Rolo
Strangles is a word that strikes fear into the hearts of many horse owners. Okay… maybe fear is too strong a word, but equine strangles is certainly an occurrence we all dread. While perhaps its reputation is deserved for the mess alone it can create, the good news is strangles is not as ominous as legend would have us believe.
What causes horse strangles?
Strangles is caused by exposure to the Streptococcus equi bacterium, and in fact Streptococcus is what also causes strep throat in humans. This bacterium is introduced through a horse's nasal passage where it proceeds to attach to the lymph nodes around the pharynx and submandibular regions (the back of the throat and under the jaw areas). The lymph nodes attempt to fight off the invading and reproducing bacteria, eventually causing a possible abscess to form.
How is strangles transmitted?
Streptococcus equi is passed on through direct exposure to the nasal discharge of afflicted horses as well as the pus that is released from abscesses. It is a highly contagious bacterium, especially among younger horses, but since direct exposure is required for it to be transmitted preventing it from spreading further is actually fairly easy. Once you have confirmed a horse is afflicted with strangles it's vital that you isolate him from all other horses – any box stall will do.
Contaminated watering buckets, ponds, bedding, hay and even fence railings can spread the disease to healthy horses, so make sure to sanitize any areas the sick horse had contact with if possible, particularly if other horses are also present in those areas. The bacteria can survive for a few weeks given the right atmosphere.
What are the signs?
If your horse comes down with equine strangles he may lose his appetite and develop a fever. In addition the lymph nodes around the throat will swell up due to the accumulation of purulent fluid (pus) caused by the nodes fighting off the invading bacteria. As the nodes expand your horse may keep his neck outstretched to relieve the pressure in his throat area.
As the disease progresses your horse will develop a very thick, cloudy mucous discharge that is enough to make almost anyone grimace. Depending on the severity of the disease as well as whether it has received any treatment, eventually the pus may collect enough to cause an abscess by which the pus can be drained.
A horse will begin developing signs of the disease about 2-6 days after exposure. Usually it will take about a week and a half to two weeks for the disease to run its course, abscesses to rupture and the pus to be drained.
How severe is the disease?
Normally equine strangles isn't too dangerous; it's just awfully miserable, messy and inconvenient for both you and your horse. That being said, once you realize your horse has developed strangles you should contact your veterinarian and have him diagnose your equine since the severity can vary and complications can arise.
Generally unless the lymph nodes swell to levels that affect the horse's ability to breathe, the disease can be allowed to run through its course. Statistics have been shown to suggest fatality rates among completely untreated strangles cases can range in 1% to 3% while another set suggested the rate was as high as 10% to 20%! I believe the latter to be significantly inflated, but in either case such statistics aren't relevant for domesticated horses since the majority of us call a veterinarian and provide care.
How should horse strangles be treated?
Much will depend on the severity and stage of your horse's case. Penicillin has been shown to be effective against Streptococcus equi, but application of it should be done during the initial stages of strangles or after any abscesses have ruptured.
Once the disease has caused abscesses to form, penicillin can actually delay the abscesses from opening and draining the pus. As such, it's usually best to let the abscess work its course (or have the vet cut it open), then apply penicillin after the draining has begun to wipe up the remaining bacteria.
There is some debate as to whether applying penicillin can actually inhibit a horse's ability to form a natural immunity against strangles, or worse provoke bastard strangles. Unfortunately there really isn't enough scientific proof to connect antibiotics to the increased chance of developing bastard strangles, but I can understand why many veterinarians would rather play it safe for light cases that can be healed naturally.
When a couple of my young horses developed strangles my veterinarian recommended allowing the disease to run its course naturally since the cases were not severe. A couple times a day I would clean the horses' nose, ensure they could breath easily, make sure they had plenty of clean water and food, and finally watch for potential worsening or complications. Within about a week the strangles worked its way through and the horses were fine.
Learn more about equine strangles in Part Two of our series Horse Strangles: Every Owner's Nightmare.