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Hairlessness is rare in horses. While selective breeding produced several hairless breeds in other domestic animals, no truly hairless horse breeds exist.
There are anecdotal accounts of hairless horses throughout history. Some horse breeds are mistaken for hairless horses due to their fine coats. Most truly hairless horses born today have Naked Foal Syndrome (NFS), a fatal genetic disorder.
Several health conditions can cause hair loss in normal horses. Healthy hair protects your horse’s skin and insulates his body, so keeping his coat in good condition is essential for overall health.
This article will discuss hairless horses, naked foal syndrome, and hair loss in horses. Keep reading to learn the difference between a hairless horse and a normal horse with a hair loss condition.
Hairless Horse History
Mentions of hairless horses appear sporadically in historical records from the 19th century.
In 1838, The Baltimore Sun published a story about a hairless horse born in New York. Other 19th-century publications from South Africa and Australia describe horses with smooth skin and no hair follicles.
Scientists don’t know what caused hairlessness in these mature horses from historical times.
Do Hairless Horses Exist?
Hairless horses do exist. Historical accounts of mature bald horses lack scientific verification, but researchers have identified genetic disorders that cause hairlessness in equines.
Unfortunately, most hairless horses die before they reach maturity. [1]
Hairlessness in Domesticated Animals
Humans have selectively bred several furry domesticated animals for hairlessness to serve as companion animals for owners with allergies. Unlike horses, these animals survive to maturity and pass the hairless trait to their offspring.
Domesticated animals with hairless breeds include:
- Dogs
- Cats
- Rats
- Mice
- Guinea Pigs
- Hamsters
Hairlessness in mice arises from mutations in the mammalian hairless (hr) gene, which plays a critical role in hair growth. Scientists selectively bred hairless lab animals for dermatology research. [2]
Research suggests a small number of genes control fur characteristics in dogs. Studies found all hairless dog breeds shared the same FOXI3 mutation, which affects the development of hair and teeth. Hairless dogs commonly have teeth defects. [3]
Hairlessness is undesirable in horses because of the adverse welfare effects. Hairless horses are susceptible to sunburn, skin inflammation, and poor temperature regulation. As a result, humans never selectively bred hairless horse breeds.
Fine-Coat Horse Breeds
Some horse breeds have fine coats and sparse hair but are not truly hairless.
Akhal Teke horses have coat hairs with more narrow, opaque cores than other breeds. These traits give their coat a unique metallic sheen. [1]
The breed evolved in a hot climate, so thin coats helped keep them cool. Humans also selectively bred them for their metallic coat sheen. While Akhal Tekes are not entirely hairless, their delicate skin and fine coats need extra protection in cold conditions.
This breed carries the gene associated with naked foal syndrome, the disorder responsible for most cases of hairless horses. [1]
Naked Foal Syndrome
Naked foal syndrome (NFS) is a genetic disorder only found in the Akhal Teke breed.
Researchers documented the first case of naked foal syndrome in Akhal Tekes in 1938, but only recently identified the genetic variants that cause the disease.
Clinical Signs
Horses with naked foal syndrome have almost no hair on their body, mane, or tail. Affected foals are born hairless and remain that way. Horses often have no eyelashes and abnormal whiskers.
Microscopic studies on skin from affected foals found hair shafts, if present, were abnormally thin and lacked structure. [1] Their skin is typically dry and itchy. The lack of protection from a standard hair coat can also increase the risk of skin lesions.
Other clinical signs associated with naked foal syndrome include abnormal teeth development, digestive disorders, chronic diarrhea, and laminitis-like problems.
One study reported heart, brain, and immune defects in a deceased foal with naked foal syndrome. [1]
Genetics
DNA studies linked naked foal syndrome in Akhal Tekes to a nonsense variant in the ST14 gene. Genetic variants in this gene are also associated with congenital skin diseases in humans. [1]
A nonsense variant produces an incomplete or non-functional protein. In this case, it leads to improper skin and hair follicle formation. [1]
Naked foal syndrome is an autosomal recessive disorder. Foals need to inherit two copies of the mutation to inherit the disease. Carriers of a single copy of the mutation do not display clinical signs.
DNA testing can help Akhal Teke breeders avoid mating two carriers and reduce the risk of producing an affected foal.
Prognosis
Naked foal syndrome is always fatal. Most foals die within the first weeks of life, but some horses survive for up to three years. Young foals typically die from digestive problems. Some owners humanely euthanize affected horses to prevent prolonged suffering.
Hair Loss in Horses
Some health conditions can cause hair loss in horses that resembles hairlessness.
Hair loss is also called alopecia. While congenital and permanent hair loss can occur in horses, most alopecia is temporary. Identifying the cause of your horse’s hair loss can help you make management decisions that will help him regain his healthy, regular coat.
Congenital Alopecia
Horses with congenital alopecia have permanent hair loss from birth. This is rare in horses, and research into possible genetic causes is ongoing.
One study describes a case of congenital alopecia that resembled hairlessness in a Percheron draft horse. Teeth and hoof development were normal, and the affected horse survived adulthood. [4]
Infection and Infestation
Bacterial, fungal, and parasitic infections affecting the skin can also cause hair loss in horses.
Mange is a rare skin condition in horses associated with mite infestation. Sarcoptic mange can lead to severe hair loss that resembles hairlessness in some animals. [5]
Ringworm is a fungal infection characterized by circular hair loss patterns. Horses can pass this infection on to humans. [6]
Hair loss is also associated with severe skin infections, such as cellulitis. Infection of the hair follicles themselves is called folliculitis. [6]
Allergies
Allergies in horses can also cause skin irritations and hair loss.
Insect bite hypersensitivity, or sweet itch, is a common allergic equine skin disease. Bites from midges and gnats can cause allergic reactions in susceptible horses. These reactions cause itching, lesions, hives, scaling, crusting, discomfort, and hair loss. [7]
Food allergies can lead to hair loss. However, allergic reactions to food are rare in horses.
Health Problems
Other health problems in horses that can contribute to hair loss include: [6]
- Autoimmune disease
- Cancer
- Fever
- Stress
- Hormonal Imbalances
- Poisoning
- Metabolic disease
Trauma
Severe trauma to the skin from injury or burns can result in permanent hair loss.
Friction caused by poorly fitting equipment and blankets can lead to isolated patches of hair loss on the skin. Repetitive trauma to hair shafts from excessive grooming, UV exposure, pesticides, and hair products can also cause hair loss.
Management
Horses with permanent hair loss need careful management to protect their skin from UV exposure, insects, and environmental conditions.
In the winter, these horses need blankets to stay warm since they don’t have natural insulation from thick coats. In the summer, fly sheets and other forms of fly protection keep insects off exposed areas of skin. Look for fly sheets and products with UV protection to prevent sunburns.
Good management can also help prevent hair loss in horses with normal coats. Regular grooming removes debris that can irritate skin and stimulates the production of natural oils.
Moisturizing sprays help protect the hair from drying out during the winter and in arid climates. Avoid products with silicone as their excessive use can lead to the accumulation of a heavy silicone layer around the hair follicles, resulting in hair breakage.
Your horse’s natural oils are his coat’s best protection. Feeding an oil or fat supplement supports the production of sebum from skin glands, which protects and moisturizes the skin.
While some equine skin conditions are treated with medicated baths, avoid overbathing horses. Frequent shampoo use can strip hairs of natural oils and dry the skin. Use a conditioner after bathing to replenish moisture.
Keep your equipment clean and ensure all tack and blankets fit your horse well to prevent hair loss from rubs. Rinse sweat off your horse after every ride. The salt in sweat can damage keratin proteins in hair, leading to a brittle coat.
Nutrition
Nutritional deficiencies, especially protein deficiencies, can slow or inhibit the growth of hair follicles in horses. Several amino acids, minerals, and vitamins are essential for coat health.
Amino Acids
Keratin is the primary structural protein in hair and is a key component of the outer layer of skin in horses. To produce keratin, horses need adequate amounts of the sulphur-containing amino acids, methionine and cysteine. While horses must obtain methionine through their diet, they can synthesize cysteine within their bodies from methionine.
The amino acid lysine is also essential for synthesizing collagen, another important protein in the skin.
Lysine, methionine, and threonine are the most commonly deficient amino acids in the equine diet. Supplementing these amino acids can support hair health in horses with protein-deficient diets. [8]
Biotin
Biotin is a B-vitamin that is also essential for the production of keratin, as well as maintaining strong hooves. While research has not established a daily biotin requirement for horses, inadequate dietary levels can contribute to poor hoof and coat quality.
Horses can get small amounts of biotin from forage. Microbes residing in the horse’s hindgut can also synthesize biotin. In healthy horses, hindgut microbes are capable of producing approximately 1-2 mg of biotin daily.
However, research shows that horses benefit from supplementation with higher levels of this vitamin. Feeding 20 mg of biotin per 500 kg (1100 lb) of body weight improves hoof wall integrity in horses, as well as supporting hair growth and strength. [9]
Essential Fatty Acids
Low-fat diets with inadequate essential fatty acids can also contribute to skin and coat health problems. Horses can’t synthesize omega-3 and omega-6 fatty acids in their body, so they must get these nutrients from dietary sources.
Incorporating oil supplements or feeds such as ground flax, which are abundant in healthy fats, can improve the natural production of skin oils in horses.
Studies also found increasing the omega-3 fatty acids in the diet improves coat condition. [10] Omega-3’s have additional physiological benefits that support skin health in horses experiencing hair loss due to inflammatory conditions. [10]
Vitamin E
Vitamin E is an important antioxidant nutrient that helps protect cells from oxidative damage and supports the function of the immune system.
Horses with a vitamin E deficiency may struggle with dry skin, allergies, or infections that can contribute to hair loss or poor coat condition. Research in humans also suggests vitamin E can help protect against UV skin damage caused by sun exposure. [11]
Fresh pasture is an excellent source of vitamin E for horses, but levels decline significantly after cutting grass to make hay. Horses without access to pasture require supplementation to meet their daily vitamin E requirements.
Copper and Zinc
Copper and zinc are trace minerals that are essential for various processes in the body, including keratin synthesis. Deficiencies in copper and zinc can compromise skin and hair integrity in horses, but supplementation with these minerals has been shown to improved hair strength. [12]
Copper and zinc are also components of tyrosinase, an essential enzyme for melanin production. Melanin is a natural pigment found in the body that gives color to the skin, hair, and eyes, playing a crucial role in protecting the skin against damage from ultraviolet (UV) light.
For this reason, horses with dark coats that do not get enough copper and zinc in their diet can experience faded coat colour and sun bleaching during the summer. Horses with lighter colored coats, like chestnuts and buckskins, need copper for their special kind of melanin called pheomelanin.
Horses need zinc and copper supplied in their diet in a 3:1 ratio. Unbalanced mineral ratios can lead to impaired absorption and utilization of these nutrients. [13]
Summary
- While hairlessness occurs in some breeds of furry domestic animals, truly hairless horse breeds do not exist.
- Hairlessness is undesirable in horses, so humans never selectively bred horses for this trait.
- Most hairless horses have naked foal syndrome, a fatal genetic disorder found in Akhal Tekes.
- Foals with naked foal syndrome do not live to maturity. Cases of mature hairless horses are rare.
- Hair loss from other health conditions can resemble hairlessness.
- Causes of hair loss in horses include congenital alopecia, skin infections, parasites, allergies, autoimmune diseases, trauma, and poor nutrition.
References
- Bauer, A. et al. A Nonsense Variant in the ST14 Gene in Akhal-Teke Horses with Naked Foal Syndrome. G3 Genes. 2017.View Summary
- Benavides, F. et al. The hairless mouse in skin research. J Dermatol Sci. 2009.
- Drogemuller, C. et al. A Mutation in Hairless Dogs Impicates FOXI3 in Ectodermal Development. Science. 2008.
- Valentine, B. et al. Congenital hypotrichosis in a Percheron draught horse. Vet Dermatol. 2001. View Summary
- Osman, S. et al. Clinical and therapeutic studies on mange in horses. Vet Parasitol. 2006. View Summary
- Knottenbelt, D. et al. The Approach to the Equine Dermatology Case in Practice. Vet Clin Equine Pract. 2012. View Summary
- Schaffartzik, A. et al. Equine insect bite hypersensitivity: What do we know?. Vet Immunol and Immunopathol. 2012.View Summary
- Mok, C. et al. Amino acid requirements in horses. Asian-Australas J anim Sci. 2020. View Summary
- Buffa, Eugene et al. Effect of dietary biotin supplement on equine hoof horn growth rate and hardness. Equine Vet J. 1992. View Summary
- Goh, Y. et al. Plasma n-3 and n-6 fatty acid profiles and their correlations to hair coat scores in horses kept under Malaysian conditions. J Vet Malaysia. 2004.
- Keen, M. et al. Vitamin E in dermatology. Indian Dermatol Online J. 2016.
- Malgorzata, K. et al. Effect of diet on mechanical properties of horse’s hair. Acta Bioeng Biomech. 2009. View Summary
- Ramin, A. et al. Evaluation of serum copper, iron, and zinc concentrations in horse and mule of Urmia. J Anim Sci Res. 2017.
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