Vitiligo Is An Immune-System Disease

My 11-year-old gray Hungarian sport horse mare has pigment loss in several areas on her body, especially around her eyes, nose, belly and chest. I actually had someone ask me if she was an Appaloosa because of the pink skin around her eyes. She gets easily sunburned and looks just plain weird. Is there something I can do to help the pigment come back? Is there possibly something missing in her diet causing this? I’ve included photos, hoping you can send me in the right direction.

Contributing Veterinary Editor Grant Miller, DVM, responds: Thanks for writing into HJ. We’re always committed to trying to help our readers learn as much as they can about their horses and manage them with proven, cost-effective products and methods. When we get a veterinary question like yours, we are happy to help you get headed in the right direction with information that may be helpful to you and your veterinarian. However, your veterinarian must be the one to actually examine the horse, make a diagnosis, and prescribe a treatment.

With that said, in general, pigment loss in horse’s coats, especially around the eyelids, is caused by a condition called equine vitiligo. It is an auto-immune disorder associated with nutritional deficiencies, including zinc, copper and/or selenium/vitamin E. However, it is very important that you discuss supplementation with your veterinarian prior to starting anything.

Horses with vitiligo should be blood tested to determine if deficiencies exist in the diet. Because it is auto-immune, your horse will likely have depigmentation for life, but you may be able to slow the progression if you can identify a nutritional deficiency and correct it.

In some cases of vitiligo, there are no detectable nutritional deficiences, yet the condition continues to spread. It commonly affects the eyelids, muzzle, face, and the teats/sheath area.

However, vitiligo is not just a cosmetic problem. It reflects other systemic issues, so please call your veterinarian.

The condition can be determined by a skin biopsy, which is a pretty simple procedure in which your veterinarian will sedate your horse (see August 2013) then numb the area with lidocaine. 

Using a small instrument (a biopsy punch) that looks like a hole puncher, your vet will take a sample of skin right on the junction of where the white and normal skin meet. Usually, the vet will take one to three samples and send it to a pathology lab for examination.

Your veterinarian also has the option of sending the photos to a board-certified dermatologist to help confirm the diagnosis. This will cost you a little more, but the confirmation will go a long way to slowing the spread. Please keep us posted on this case.


What kind of psyllium (January 2013 article on insulin-resistant horses) do you recommend for horses? My horse is not diagnosed as insulin resistant, but she’s showing some signs of it, and I think your suggestion that it can’t hurt and may help is a good one. 

She has fat deposits behind her shoulders and has had a cresty neck, so I would like to be proactive. But choosing a product is not easy. I’ve found there are husks, powder and capsules. The article said to use 1/3 to 1/2 of a cup. I called a Natural Food Co-Op and it’s about $10 a lb. How many cups in a pound? I was told it is quite light weight. This could be expensive it seems?

Nutrition Editor Juliet Getty, Ph.D., Responds: The outer husk of the psyllium seed has been shown to reduce blood glucose levels in humans. Intrigued by this benefit, researchers at Montana State University evaluated its potential for horses. They found that a daily portion of psyllium husks reduced circulating insulin levels. The reason for this lies in its high water-soluble fiber content. It forms a gel inside the horse’s small intestine which inhibits the absorption of glucose, thereby lessening the amount of insulin needed from the pancreas. 

Three daily dosages were used in this study—90, 180, and 270 grams—all of which produced the same benefit. The lowest dosage, 90 grams per day, is equivalent to approximately three ounces by weight. In terms of volume, it would fill six fluid ounces in a measuring cup.

Since psyllium reduces glucose absorption resulting from sugar or starch digestion, it’s best to provide a dose each time you offer your horse a concentrated meal. If you feed twice daily, add three fluid ounces (90 ml) of psyllium husks to each meal. One pound (16 ounces by weight) of psyllium husks would fill a 32-fluid-ounce (quart) container. With a minimum dose of six fluid ounces per day, one pound would last you five days. 

Feeding psyllium husks is one of several tools in managing insulin resistance, if your horse is insulin resistant. It should be combined with a low starch/low sugar diet, one that removes all cereal grains, sweet feeds, and sugary treats. Your hay should be low in non-structural carbohydrates (NSC) and fed free-choice, to avoid the hormonal response that promotes obesity when forage is restricted.

Coconut Oil For ulcers

A few of my friends claim that coconut oil is the optimal choice for a horse battling ulcers. Is that true?

Contributing Veterinary Editor Grant Miller, DVM, responds: Indeed, coconut oil has its benefits. It’s well regarded for its ability to improve hoof and hair health. However, there are virtually no omega-3 fatty acids in it. For this reason, we feel there are far better choices for ulcers and for hair/hoof health. 

Blankets or no blankets

Our winters aren’t too bad, but we do get freezing rain. While my horses are turned out 24/7, they only have trees for shelter. Sometimes I wonder if that’s enough during ice storms and freezing rain.

Contributing Farrier Editor Lee Foley Responds:While a horse’s natural winter coat will give him protection from rain/snow and from cold, when you combine them, it can become too much. The question is whether the trees are enough to block wind and stop the wet from penetrating to the skin. We suggest you consider a waterproof breathable lightweight blanket that will give them some added protection. Use it for extra coverage when the forecast is bad.

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