Scratching the Surface on Mites in Horses (Mange)

Updated March 29, 2024 | By: Jamie Whittenburg, DVM

Mites can be quite a nuisance and are consistently found to be a cause of skin issues in horses. When a horse is infested with mites, they are said to have mange (generic term for the condition).

Unlike lice, mites are not insects, but are members of the Arachnida class, like spiders. They are parasites that depend on a host organism for survival.

It is essential to recognize, diagnose, and treat horses with mites as it can severely affect your horse’s quality of life.

Types of Mites That Affect Horses

Mange in horses may be caused by several different types of mites.

• Sarcoptic mange: Caused by Sarcoptes scabiei and commonly called scabies or body mange. It often results in an extremely itchy horse with hair loss and areas of irritated, reddened skin. Sarcoptic mange may also affect humans and other animals, so appropriate protective measures should be taken.
• Psoroptic mange: Commonly referred to as ear mites (Psoroptes cuniculi [ovis]). They are commonly found in the ears and cause scabbing and crusting inside the outer ear canal. Horses with ear mites often become head shy.
• Chorioptic mange: Attributed to Chorioptes equi (bovis), this form is also called leg mange or feather mites. Primarily affecting the lower limbs in breeds with longer hair or “feathers” on their legs, chorioptic mange causes itching and skin irritation.

Life Cycle of Mites

A mite at any stage of its life cycle can live on its host (in this case, a horse). Eggs laid by an adult female onto a horse’s hair will hatch into larvae. The larvae then become nymphs, which mature into adults. The entire process takes only about 21 days.

Horse mites are more commonly found in cooler climates and during the winter months. Adult mites can survive off of their host for about two to three weeks, given the right conditions.

Identifying a Mite Infestation in Your Horse

It is crucial to recognize the signs of a mite infestation so your horse can be promptly treated, and the mites prevented from spreading. Signs that may indicate your horse is suffering from mites include:

• Persistent itching
• Aggressively rubbing or scratching the head, ears, tail, mane, or other parts of the body
• Biting at areas of the body
• Red skin
• Scabbing and crusting areas of skin (may also ooze fluid)
• Patchy hair loss
• Frequent head shaking, head shyness, and increased sensitivity around the ears

Occasionally, mites can be seen with the naked eye, crawling on the skin or inside the ear canals. They look like very small white flecks that move.

Unfortunately, horses can have low numbers of mites and not show clinical signs. However, these horses may still serve as a source of transmission of the parasite to other horses. This can happen either through direct contact between horses or indirect contact like transferring mites on brushes, tack, and other barn equipment.

Diagnosis of Horse Mites

Horses with a mite infestation are very itchy and will typically be seen rubbing their body against objects, like stall walls or fences, and biting themselves. They may also be reluctant to have anyone touch their ears. Skin in the areas that mites have colonized will often be thickened, red, and scabbed.

If you suspect that your horse may be suffering from mange, call your veterinarian. Your vet will perform skin scrapings of the affected areas and take swabs of the outer ear canal. They’ll view these under a microscope to identify the mites.

The presence of mites may make your horse very reluctant to have their ears examined, so it may be necessary for your vet to administer a sedative to your horse before attempting to obtain an ear swab. This will ensure your horse’s comfort and safety for the veterinarian.

Treatment Options for Horse with Mites

For most mite infestations, your veterinarian will prescribe either a topical or oral acaracide, such as ivermectin or moxidectin. In some cases, it may be necessary to treat with both forms of medications as mites may not ingest enough blood to be affected by systemically administered medications.

Always be sure to follow label directions and wear personal protective equipment such as gloves and eye goggles when working with these products. A topical shampoo that works to remove crusting and scabs from the skin may need to be used on affected areas before treatment.

It is also prudent to shave or closely trim hair in the infested areas. This will allow for better contact for topical medications and sprays. Regular check-ups and monitoring are essential for assessing how treatment has worked and ensuring your horse's overall well-being.

Stopping Further Spread

Some horses won’t show any signs of an infestation, so the mites or eggs can easily be transferred by tack, brushes, and equipment, which is an issue. If one horse in a barn or a herd of horses are diagnosed with mange, then all the horses in the stable should be treated. The facilities, grooming supplies, and tack on the premises should be thoroughly cleaned and treated with a spray acaricide if possible.

Supplements supporting your horse's recovery may be recommended, but consultation with a veterinarian is essential. Examples of supplements that may be helpful include prebiotics, probiotics, and other immune system supporters.

It is never a good idea to ignore a known mite infestation. Long-term mange can result in severe complications, including ear infections, hearing loss, and chronic discomfort for your horse.

Tips to Prevent Mites at Your Barn

• Since mites are easily transmitted between horses, maintaining a clean environment through regular grooming and hygiene practices is vital.
• Brushes, tack, and equipment should ideally not be shared between horses. If they must be, brushes should be thoroughly cleaned between uses.
• It is prudent to quarantine new horses before they enter a group to prevent the introduction of mites and other potential health risks.
• Speak with your veterinarian about environmental management strategies, like regular cleaning of stables and pasture management, to help minimize the risk of an infestation.
• Owners should ensure their horse is regularly, thoroughly groomed and fed a high-quality, balanced diet.

Key Takeaways

Horse owners should always be vigilant and pay attention to their horse’s behavior. Any change from your horse’s norm, like scratching and biting at themselves or areas of hair loss and irritated skin, should be investigated.

Taking action as soon as possible is key in decreasing the impact of mite infestations and safeguarding your horse's health. If you suspect your horse may have mites or something else, it’s strongly encouraged that you reach out to your veterinarian.

For more information, reference these guidelines on mites from the American Association of Equine Practitioners.