Table of Contents

Hair Loss in Horses

Table of Contents

Is my Horse going Bald?

Hair loss in horses is a symptom of another issue. Understanding the biology of the horse is helpful in determining the root cause. Careful observation can provide clues to the problem. Often, insect activity can be to blame, but certain bacteria, fungi, or tumors can also cause hair loss. It’s always a good idea to work with a veterinarian to determine the underlying cause and develop a treatment plan.

Why do horses lose their hair?

Hair loss is a symptom, not a disease.

To start, it helps to understand what is normal. Hair grows beneath the skin’s surface. The hair follicle is the source of the hair’s growth and anchors the hair into the skin. Surrounding the follicle is the sebaceous gland, which produces sebum. Sebum is an oil with antibacterial properties to protect the skin. It also gives healthy hair a glossy shine.

After hair is lost, it takes three to six weeks to regrow, depending on genetics.

Hair growth is triggered by the amount of daylight, not temperature or weather conditions. As hours of daylight get shorter, horses begin to grow a thicker coat to keep warm during the winter. Subsequently, as days lengthen in the spring, the hair starts to shed out into the thinner, glossier summer coat. 

What Causes Horses to lose their hair?

Is your horse scratching too much?

Trying to pinpoint the cause of hair loss can be difficult. Take time to observe your horse for clues. Is your horse itching and rubbing out the hair? If the hairs are bent or broken, and the skin is red or scabbed, it is a sign that the horse is scratching and the hair is being rubbed off. If there are no signs of itching, it is more likely that the hair falling out on its own, which could be caused by a disease.

Insect Related Hair Loss:

Biting Gnats

Biting gnats are one of the most common causes of itching in horses. The saliva of the Culicoides fly can cause an allergic reaction, commonly known as sweet itch.

Diagnosis: visual, although may require the assistance of your veterinarian.

Treatment: Property management to eliminate or minimize insect activity, and corticosterioids or antihistimines to manage the immune response.

Lice

A lice infestation could also cause scratching, leading to hair loss.

Diagnosis: Visual. Look for dandruff that moves; if you find lice, don’t panic—they are species-specific, so you shouldn’t be able to get lice from your horse.

Treatment for lice requires bathing with a medicated shampoo specifically aimed at de-lousing livestock. You can also apply topical pyrethrin or permethrin products and oral ivermectin. It’s important to thoroughly wash and clean anything that may have come in contact with the horse to avoid re-contamination (grooming brushes, blankets, saddle pads, etc.)

Threadworms

Another culprit could be neck threadworms. Onchocerca cervicalis, a parasite transmitted by the saliva of infected gnats, release microfilaria throughout the horse’s skin. As they die, they cause itching which could result in hair loss.

Diagnosis: Visual, may require the assistance of your veterinarian.

Treatment: Property management to eliminate or minimize insect activity, and oral ivermectin 2-3 times per year.

Mange

Mange also causes itching and hair loss, although it is not very common in the United States. Biting mites are typically seen around the mane, forelock, base of the tail, or in long leg hairs.

Diagnosis: Examine skin scrapings under a microscope.

Treatment: a combination of oral ivemectin and topical ointment prescribed by a veterinarian.

Heat and Sweating can Cause Hair Loss

The simplest cause of seasonal hair loss in the summer months is related to heat and sweating. During hot, humid months, horses can experience extra sweating under the mane, where heat is trapped. This additional moisture can cause the hair follicle to soften and the hair to fall out. Additionally, the salt content of the horses’ sweat can be an irritant to the skin, also leading to hair loss. This is common to see around the eyes and ears, as many horses don’t enjoy having their faces washed.

Diagnosis: Visual.

Treatment: Careful grooming and extra baths in the summer are a good preventative measure. However, even the best-groomed horse could still experience hair loss; it may just be considered normal for that particular horse.

Seasonal Alopecia causes Horse Hair Loss

Seasonal alopecia is caused by an inbalance in the pineal gland. This may cause the horse to shed out unevenly and exhibit bald patches. If the skin underneath looks normal, continue to observe the horse.

Diagnosis: Visual.

Treatment: Keeping horses under adequate lighting year-round can help mimic natural sunlight and prevent a horse from growing (and subsequently shedding) a heavy winter coat.

Fungal Infections cause Hair Loss

Dermatophytosis is a fungal infection on the skin that causes patchy hair loss. The patches are usually oval to round in shape and are referred to as ringworm, even though it is not caused by a worm at all. While ringworm is more common during fall and winter months, it can occur year round. This type of infection is highly contagious, one of the reasons why maintaining separate tack and grooming equipment for different horses is important.

Diagnosis: A veterinarian will pluck some hair from the affected area and test to see if the fungus is the airborne type (more common) or something more serious.

Treatment: Many topical antifungal ointments are available over the counter or can be prescribed by your veterinarian. Use extreme caution when evaluating home remedies; when in doubt, ask your vet before trying anything you wouldn’t put directly on your own skin. Similar to lice, anything that may have touched the horse should be washed and cleaned to avoid re-infection.

Rain rot can cause hair loss

Rain rot, caused by a bacteria, is more common during winter months. It causes hair to fall out in tufts, leaving a bald spot behind.

Diagnosis: Visual, or your veterinarian can look at a skin scraping under a microscope. This disease is commonly mistaken for ringworm.

Treatment: Modify living conditions to eliminate excessive moisture in the horses’ coat. Bathing with an antimicrobial shampoo and removing scabs can clear up the issue. Advanced cases may require antibiotics.

Sarcoids will cause Hair Loss in Horses

Sarcoids, or skin tumors, can also cause hair loss. These lesions are flat and hairless, but do not appear to be painful. They are generally benign, but can be locally invasive.

Diagnosis: Your veterinarian may want to biopsy the lesion for an accurate diagnosis.

Treatment: Sarcoids are difficult to treat. Different treatments include excision, cryotherapy, laser treatments, topical drugs, and injections3. Recurrence is common, leading many veterinarians to opt out of treatment unless it is causing the horse pain.

Tack or equipment that does not fit properly.

Diagnosis: If hair loss is where the saddle, girth, bridle, or halter sit, check for fit. Ill-fitting tack can cause hair loss and even sores. Depending on the extent of the damage, the pigment in the new hair could be affected, re-growing in white. It’s always a good idea to ask for help from a trainer, vet, or equine professional if you are unsure about how to properly fit your horse. Blankets can also rub, causing hair loss. This is common to see along the withers or shoulders. Fitting your horse with a sleazy underneath the blanket can be a quick fix.

Treatment: Discontinue use of any item immediately if it does not fit correctly. If the bald spot is in the saddle or girth area, the horse may need some time off to re-grow the hair.

Conclusion

There are many different causes of hair loss in horses. Keenly observing your horse and examining the surrounding environment can provide clues to the root cause. While there is a lot of good information out there, it’s always a good idea to consult with a veterinarian to figure out exactly what is going on and create an appropriate treatment plan.