Strangles

By Jennifer Kunz, AnimalForum.com staff

Strangles is the common term used for the condition caused by the Streptococcus equi bacterium. The name strangles comes from the fact that in certain cases throat abscesses grow so large that they cut off the trachea and actually strangle the horse. The strangles bacteria causes an upper respiratory infection which can spread to the lymph nodes.

The incubation period for strangles is 4-8 days. The organism gains entry through the pharynx and rapidly infects the local lymph glands, especially those which lie between the lower jaw-bones. The horse develops a very sore throat and swallowing becomes difficult. At this stage, the temperature is generally very high, the horse looks ill, does not eat or drink and a thick discharge of mucus appears at the nostrils. The lymph glands become hot and painful, swell up and eventually burst, releasing copious amounts of evil-smelling pus. Once the glands have burst, the swelling rapidly diminishes, the pain and fever disappear and the horse starts to recover. Mild cases of strangles do occur and typically include minor swelling and fever, but no serious abscesses or rupturing. Infection in 1-5% of cases may spread to other organs of the body: this is usually fatal and is called Bastard Strangles.

Strangles is very contagious, especially with foals, spreading easily from horse to horse and often leading to large outbreaks with many horses affected. It is spread in the discharges from the nose and burst abscesses. Objects such as water troughs, feed buckets, brushes, reins and other equipment can also spread the disease. Recovered horses can spread the disease for up to eight months, even though they can appear clinically healthy and normal. The bacteria can stay alive in infected premises for up to a year. To prevent the spread of strangles, immediate isolation is necessary. This includes separate tack, feeding equipment, separate drainage and air space.

The drug of choice for dealing with strangles is penicillin which should be given in large doses for at least seven days after any abscesses have burst. Sick horses should be isolated somewhere warm and dry and the whole barn and all equipment disinfected immediately.

A regular program of vaccination can assist in strangles management although the vaccine is not a complete preventative and may cause side effects in some horses. Strangles outbreaks are very unpleasant experiences for both horses and their owners. Often horses will need to be isolated and laid off training for as long as three months to recover completely from the disease. Exposure to the disease can create immunity to it in the future, but it has been estimated that up to 25% of all horses never develop that immunity.

Perhaps the best method for controlling the outbreak and spread of this disease is good horse management. Healthy horses are more able to resist the complications associated with strangles. New horses arriving at a farm or stable should be isolated and observed for a significant time period, until the horse can be pronounced free of ANY contagious disease. Stalls, tack, and any equipment used in the maintenance of horses should be cleaned and disinfected regularly.

Speak to your veterinarian today about preventing and controlling this disease. Your horses deserve the best!