Last Updated on April 5, 2022 by Allison Price
Horses can have vitiligo, which is an unsightly skin condition. However, it is essentially cosmetic, according to a newly published scientific review.
“Therefore any treatment for the disease should always be discussed between the owners to avoid interventions with dubious efficacy or those with potential adverse effects,” Thierry Olivry wrote with his colleagues in the journal BMC Veterinary Research.
Researchers acknowledged that vitiligo can have a negative effect on show animal owners.
Vitiligo, an autoimmune condition in which melanocytes are destroyed in the skin, is called “Vitiligo”.
This condition was covered in a large part of their research into autoimmune disorders affecting skin melanocytes (skin cells) in horses, dogs, and cats. They said that it has many similarities to the human condition.
Depigmentation occurs when melanocytes are destroyed in vitiligo.
This is the most common form of depigmentation in humans and affects 0.5 to 2 percent of the population. In India, rates as high as 8.8% were reported.
These signs are most noticeable in the skin, lips, and/or oral cavity.
More than 3500 years ago, the first human case of vitiligo was described. Vitiligo, which was mistaken for leprosy or other depigmenting disorders in ancient times, led to discrimination and social stigmatization that still exists today.
Only in the past century has vitiligo been more popular among medical researchers.
In 1971, scientific literature published the first case series on vitiligo in dogs. There are few scientific reports on vitiligo in dogs, cats, and horses.
It was first reported in horse literature in 1931. However, it wasn’t until 1960s that a Dutch veterinarian published three papers on equine Vitiligo.Dr. J. Davis provided this photo of a horse with one large, unilaterally depigmented patch just below his right eye.
It is not possible to estimate the incidence or prevalence of vitiligo among horses, dogs, and cats based on available data.
Cornell University reported that vitiligo was responsible for 0.7% of all equine skin diseases examined at their veterinary teaching hospital.
The review team stated that “vitiligo prevalence in animals could be much higher than reported.”
“However, this disease is primarily a cosmetic issue in animals and may not motivate owners to seek veterinary care.”
Five reports that were compiled by the authors and which included 32 horses, can help us determine the breeds of horses with vitiligo.
There were twelve Gelderlands, nine Spanish thoroughbreds and four Arabians among these cases.
Other studies have not identified breeds.
Three reports with 28 horses describing the sex of affected horses provided information on the sex of these horses. The ratio of female to male was two to 1.
They stated that Vitiligo has been reported to be common in Arabian horses, the so-called “Arabianfading syndrome” or “pinky Arab”, and that there are many references listing this breed in review paper and in the literature.
The published information may not be complete and it is possible that the condition is more common among horses than is known.
Only seven horses reported the age at which onset occurred, with a median of 48 month and a range from 1 to 18 year.
Only six horses had information on the appearances of the first skin lesions. All of them developed depigmentation in the head/face region.
There were 11 horses that had the lesion distribution, with eight of them (73%) affecting the head/face area.
They noted that the cosmetic nature and treatment of the disease is often done clinically, without the need for skin biopsies.
The researchers also noted that treatment can have a severe psychological impact on the quality life of the affected people. This is why aggressive treatment can be used for widespread, facial, or recalcitrant forms of vitiligo.
Horses: Only 11 horses were able to provide information on treatment and outcomes in three reports.
Significant repigmentation took anywhere from one to twelve months.
One horse was completely repigmented after being given oral nutritional supplements, including vitamin A, D and B12, which included vitamin E.
Another report showed that partial repigmentation was possible after taking high amounts of chelated copper. After the copper supplementation was stopped, a relapse of depigmentation took place about five months later. Then, a clinical improvement was observed when the daily intake was increased.
They said that it was plausible that the horse’s depigmentation was due to a copper deficiency, and not vitiligo.
One case report showed that nine horses had complete repigmentation following a year of carrot dietary supplementation (4-5kg per animal per day).
The author thought that high amounts of a thyroprotein product could have led to depigmentation and a relative vitamin-A deficiency. The authors are not aware of any evidence that vitamin A deficiencies cause depigmentation in horses, but several studies in humans have shown that deficiency in D and B12 vitamins can be associated with vitiligo.
“So, it is important to interpret the nine horses in this report with caution. One possible cause could be an idiosyncratic response to high levels of a product containing thyroprotein or its ingredients. The cessation from this diet led to spontaneous resolution.
The review team stated that information about the long-term treatment of vitiligo in dogs was not available, and there were very few published case reports.
It is best to avoid interventions that are questionable in effectiveness or have potential adverse effects, due to its cosmetic nature in animals.
Highly potent glucocorticoids can be applied topically to show animals where they could have negative effects on their owners. It would only be useful for areas with little or no hair. You should use it sparingly.
“This recommendation is based upon the assumption that the pathogenesis and treatment of vitiligo in animals and humans is similar. It involves an autoimmune mechanism.”
They stated that vitiligo treatment by glucocorticoids is not recommended because of the negative effects on animals.
Oral supplementation with Lphenylalanine can be tried for six months if topical therapy fails. However, clinical remission may be limited. You might also consider supplementing with topical glucocorticoids.
“It is important that owners are aware that although these treatments may stop depigmentation from progressing, they don’t guarantee repigmentation.
According to the authors, research is needed to find out, among other things whether the same genes that cause vitiligo in humans play a role in the diseases in horses, cats, and dogs.
Phototherapy is an effective and safe treatment for humans. “Phototherapy, whether used alone or in combination, is safe and effective treatment for humans.”
Olivry was joined by Keith Linder, a North Carolina State University colleague; and Heng Thham, from Virginia-Maryland College of Veterinary Medicine.