Horse Care: Coat of Envy

A horse’s genes determine if it dapples

story by Katie Navarra

There is nothing more eye-catching than a sparkling, dappled coat. The concentric circles suggest the horse is well-fed and in good health. Owners take great pride in a horse that has a dappled coat because it speaks to their horse care skills—it signals the horse is receiving topnotch nutrition and care.

“Most dappled horses are fit, sleek, and in good shape nutritionally and physically,” said D. Phillip Sponenberg, DVM, PhD, ACT, a professor of pathology and genetics at the Virginia-Maryland College of Veterinary Medicine. “In that sense, they are sort of the icing on the cake and (on average) are part of the mental picture of a good horse in good shape.”

Nutrition plays a role in dappling, but it alone does not influence the pattern. The concentric rings typically appear on gray horses, but the spots can occur in any coat color that mixes black hairs into others, explained Kathleen Crandell, Ph.D., a nutritionist with Kentucky Equine Research (KER) in Lexington, Ky.

Dappling is a variation in the red or black hair shaft pigments and is controlled by variation in the intensity of the expression of the coat color. If the horse doesn’t have the genes, changing feeds and supplements will not bring out dapples.

Dark pigmentation is the key to dappling. Chestnuts can have dapples, but they are much fainter than those on grays because they lack the dark pigment eumelanin, which is responsible for black or brown color in hairs. Pheomelanin is the dominant pigment in reddish hairs.

“There can still be variations in the strength of the color which may show as dappling, but they will never be as obvious as that in a horse with black or brown in their hair color,” said Dr. Crandell.

Most dapples are light centrally and darker peripherally. Donkeys and roan horses often reverse that relationship, according to Sponenberg. Bays, chestnuts, palominos and buckskins can also dapple. In gray horses, if they are flea-bitten or become whiter from aging, the dapples will fade, which has nothing to do with their overall health.

“One thing people don’t realize is that dapples are on the hair, not the skin,” Dr. Crandell said. “There is this misconception that any horse can get dapples if you feed it right and that’s not true. Since the dapples are on the coat, and not the skin, that means they can disappear with clipping. Don’t be too hard on yourself if the dapples disappear.”

While nutrition alone cannot make a horse dapple, it is a key ingredient to a healthy coat. However, certain vitamins and minerals that support coat health make the dappling even more impressive.

There is no scientific study to confirm if dappling is more or less present in horses today. Anecdotally, Dr. Crandell has seen more dappling in horses than in years past, a trend she attributes to the growing awareness of proper nutrition. Horses today are eating concentrated feeds fortified with a good balance of minerals rather than the traditional straight oats.

“Horses on fresh green grass are more likely to show dapples than horses on hay, and that is probably because of nutrients, like beta-carotene, in the grass,” said Dr. Crandell. “Grass loses vitamins A and E after it is cut and dried. Vitamin A in particular is one of these nutrients that are important in the coat and skin.”

High-quality protein and certain amino acids—in particular lysine and methionine—provide the foundation for a healthy coat. Forages tend to be low in minerals like copper and zinc, Vitamin E and beta carotene, so providing a feed or ration balancer with those ingredients can make up for any deficits.

“Copper needs to be in balance with zinc. Supplements always need more zinc to support absorption,” said Dr. Crandell. “My best advice: leave it up to feed and supplement manufacturers who make hoof and coat supplements instead of trying to be the chemist. That is a recipe for problems. The exception might be if you’re working with a nutritionist who is formulating something for you to get the right balance.”

Having a properly balanced diet is the best thing to ensuring coat health.

Having a source of fat can also be beneficial, according to Clair Thunes, Ph.D., an independent equine nutritionist. She operates Summit Equine Nutrition LLC in Gilbert, Ariz.

Fatty acids from high-fat seed meals like flax support a healthy shine. When giving fats in oils, Dr. Thunes prefers omega-3 fatty acids rather than those high in omega-6. Omega-3 fatty acids may decrease skin irritation and improve the horse’s skin quality.

Dr. Thunes said that in her 13 years of practice, no one has asked her how to feed their horses to achieve dappling. However, it has been a priority among horse owners for years. She said she has heard that old-time horsemen and women believe protein is the key to dapples and look closely at labels for protein levels. Similarly, Dr. Crandell found an old Aussie recipe formulated specifically for encouraging dapples.

“It used the full-fat soybean (not the meal), roasted or ground; black oil sunflower seed; and ground flax/linseed,” Dr. Crandell said. “Even if the horse doesn’t dapple, at least his coat will have a brilliant shine.”

The key to creating a glossy coat starts with basic horsemanship skills. A dull coat, dappled or not, is an indication of other issues. Parasites and stomach ulcers are two conditions that can influence a horse’s health, so monitoring their health and working with a veterinarian are essential. Grooming can have the most significant impact on coat health. It’s tempting to skip a thorough curry when time is ticking, but spending the extra time makes a big difference.

“Dappling will come out without brushing, but really it’s the proper and frequent grooming that brings them,” said Dr. Crandell. “With a good brushing, you’re distributing the natural oils throughout the coat. That makes the hairs shine and brings out the dappling as well.”

Dapples express themselves at different times of the year. They may be brilliant in the summer and fade away in the winter. One thing is for sure, good year-round grooming routines add a glistening sheen to every coat regardless of the season.

“No matter if you provide the best care and nutrition, if your horse is not genetically predisposed to dapples, they won’t occur,” Dr. Thunes said. “So, if you are doing everything right and there are no dapples, it may not be you, it may be your horse.” HB

Katie Navarra is a freelance writer living in New York. To comment on this story, email us at readerforum@ustrotting.com.