Mange is a rare skin condition caused by various types of skin mites that can affect all breeds of horses. It is extremely itchy and irritating, and severe mite infestations can cause progressive skin lesions from mite damage and scratching. If left untreated, mange lesions can become widespread over a horse's body, leading to great discomfort and emaciation due to anorexia. Several topical and systemic treatments are available from equine veterinarians to treat this uncommon but potentially serious ailment.
What Is Mange?
Mange refers to an infestation of a horse's skin by various types of parasitic mites that feed by piercing the skin or burrowing in it, depending on the type of mite. There are four different types of mange in horses, including chorioptic (leg) mange, sarcoptic mange, psoroptic mange, and demodectic mange. Each type of mite causes irritation, but some are easier to eradicate than others. In addition to treatments that kill the mites, antibiotic therapy may be required to help a horse's skin heal.
For many years, mange in horses was a reportable disease, meaning the federal government had to be alerted if an infestation was diagnosed by a veterinarian. As of 2006, however, the condition was declared rare enough that it was no longer reportable in horses in the United States. It still exists, though, in a small number of cases each year. Very young horses, senior horses, and immunocompromised horses are more likely to be affected by mange than adult horses in top condition.
Symptoms of Mange in Horses
Signs of mange are usually evident shortly after infestation. Mange in horses is more common during the cooler months when horses' longer coats provide insulation and increased moisture that mites are drawn to.
Skin infested by mange mites will weep fluid, becoming dry, crusty, thickened, and red. In response to the biting and burrowing mites, a horse will be very itchy. To relieve the itch, the horse may kick, stomp, roll, bite itself, or rub itself on fences or trees, causing more skin damage.
If left untreated, the affected skin will become thickened and chronically inflamed, causing the horse to lose condition.
Causes of Mange
Mange is a skin condition caused by microscopic mites. Mites are eight-legged ectoparasites that bite or burrow into the horse's skin and cause intense itching. Certain types of mites have a predilection toward certain places on the body—the ear area, fetlock, pasterns, between the legs, or elsewhere on the body.
Diagnosing Mange in Horses
A physical exam of affected skin may be the only diagnosis required by your veterinarian to determine a course of treatment. Depending on the location of the lesions, a vet may also perform a skin scraping to detect specific mite species under a microscope.
Once mites are identified, a horse may be treated with an acaracide wash and an oral parasite medication like ivermectin. The treatment may need to be repeated because mites may take several weeks to complete their life cycles.
Since the mites may persist for a short time on the horse's brushes, tack, and stable, all must be washed to prevent further spread. It's important to wear gloves during the treatment time and take care not to pass the mites on to other animals.
In a herd situation, all horses should be treated to completely eradicate the mites, and severe skin lesions may require antibiotic medication to cure secondary bacterial infections.
Prognosis for a Horse With Mange
Mange can spread easily from horse to horse by physical contact, and mange mites can live for short periods in warm, damp conditions such as saddle pads, blankets or tack, and other items the horse may come in contact with. If all horses and tack are treated for the duration of time recommended by a veterinarian, the mange problem should be eradicated, and the horse (or horses) will likely be free of the itchiness within a few weeks. More severe lesions may take longer to heal completely.
How to Prevent Mange
Keeping your horse in good health is the key to avoiding many problems. It is a good idea for each horse to have its own tack and brushes. Any new horses brought into a stable should be carefully examined and isolated if there is any health concern. If you suspect mange or any other skin problem, clean all tack and brushes with the appropriate spray or wash and practice good hygiene—gloves and handwashing—to prevent spread.
Types of Mange in Horses
There are four different types of mange in horses:
Chorioptic (leg) mange: Mites of the Chorioptes bovis species cause chorioptic mange, also known in horses as leg mange. It is most commonly found in draft horses with long feathering hair on their legs. This type of mange can cause severe swelling and lameness.
Sarcoptic mange: The most severe form of mange in horses is caused by the Sarcoptes scabiei var equi mite. The first sign is intense itching, followed by crusty lesions, particularly on the head, neck, and shoulders. In this form of mange, hairier regions and the lower extremities are not usually affected. Infested skin becomes lichenified, or thick and folded, and may cover large areas of the body. Untreated, this form of mange is likely to cause health deterioration, weakness, and weight loss.
Psoroptic mange: Mites of the Psoroptes ovis and P. cuniculi species infest and cause lesions on the hairiest parts of horses' bodies, including the mane, tail, fetlocks, and chin.
Demodectic mange: Hair follicles and sebaceous glands are susceptible to overgrowth of normal skin mites of the Demodex equi or D. caballi species. mites infest hair follicles and sebaceous glands. D. equi occurs all over a horse's body, but D. caballi are limited to the eyelids and muzzle. Immunocompromised horses are most vulnerable. The lesions caused by demodectic mange are not very itchy, and they often resolve without treatment, especially if a horse's overall health condition is improved.