Coat Improvement With Supplements?

Your horse's coat isn't looking as good as it should. Your neighbor attributes her horse's fantastic coat to a supplement she's been using--but then, this is the same neighbor who swears by a lose-fat-while-you-sleep supplement for herself. With a myriad of tempting advertisements for equine nutritional supplements, each promising to improve health or condition and generally backed by numerous testimonials and little or no research, it's difficult to know what to believe, which product to turn to, or where to get solid data.

The truth is, the consensus among many veterinary experts is that a nutritional supplement won't improve the coat of a healthy horse which is properly groomed and fed a complete and well-balanced diet suitable for its stage of life. However, nutritional supplements that correct deficiencies in the horse's diet can lead to improved coat condition--and some from the veterinary community believe that overall, horses' diets just aren't what they should be.

Living In Dullsville

A scruffy, thin, or dull coat can occur for several reasons, many of which are related to nutrition. At the top of the list are dietary deficiencies.

A complete, well-balanced diet for the age and activity level of the horse is important for health and a quality hair coat. Says Randel Raub, PhD (animal science), Associate Professor and Horse Teaching and Research Specialist at Kansas State University, "There are different nutritional needs depending on the type and intensity of the horse's use: some horses are pretty much pasture ornaments, and others have to work for a living. There are also different nutritional requirements for the young growing horse, the adult horse, and the geriatric horse." In other words, a complete and well-balanced diet for one type of horse might contain deficiencies (or excesses) for another type.

Particular nutrients have been linked to coat quality. Craig D. Thatcher, DVM, PhD (nutritional physiology), Dipl. ACVN, Department Head of Large Animal Clinical Sciences at the Virginia-Maryland Regional College of Veterinary Medicine, notes, "Protein or vitamin E deficiency, and vitamin A deficiency or excess, can result in a long, scruffy-looking hair coat. Inadequate amounts of trace minerals such as iron, zinc, selenium, and copper may also be reflected in coat quality. Hair growth and shedding are slowed, resulting in a rough, coarse, unkempt appearance.

"Particularly, the sulfur-containing amino acids (the building blocks of proteins) are important for hair production. The diet should contain appropriate concentrations of these nutrients, but if these concentrations are present in the diet, no additional protein or vitamin A is necessary."

Essential fatty acids play an important role, too. Explains Sarah L. Ralston, VMD, PhD, Dipl. ACVN, Associate Professor in the Department of Animal Science at Rutgers University, "Most horse rations are only 2-3% fat, and horses seem to do well on this amount. However, adding vegetable or corn oil helps provide additional essential fatty acids that may be lacking in some feeds."

The ability to utilize available nutrition is another factor. Doug Herthel, DVM, founder of Alamo Pintado Equine Medical Center, a large equine surgical/medical referral center in Los Olivos, Calif., says, "The coat is an indication of health. The veterinarian should check to make sure the horse has good dental occlusion (bite alignment); poor occlusion in itself will cause malnutrition. Make sure the horse is not picking up sand as it grazes, which can lead to low-grade malnutrition secondary to chronic sand irritation. Be sure there are no stomach ulcers. That will cause poor hair coat because of the digestive component. Make sure there is no parasite problem."

The quality and type of coat also can be partially linked to genetics. "Genetics is a component in just about every other aspect of the horse's condition, so I don't know why it wouldn't play an aspect in coat quality," Raub says. "It's probably not so different than variations you see in human hair--some people have hair that is drier and more brittle, others have hair that contains more natural oil."

Additionally, good grooming goes a long way in producing a good-looking coat. "What probably improves hair coat the most is proper grooming," Thatcher emphasizes.

Necessary Nutrients

Generally, supplements used for improving the coat involve extra fat and/or extra vitamins and minerals.

Fats--"Vegetable oils add a nice sheen and do seem to help horses shed out in the spring," Ralston says. "Although horses are adapted to a low-fat diet and are not known to require the essential fatty acids required by omnivores and carnivores, some supplementation (one-quarter cup or less for a 1,000-pound horse) does seem to help, especially in the spring."

Thatcher notes, "Oils that can be used successfully are corn, safflower, linseed, and soy. The oil can be top-dressed to the grain portion of the diet. It will take several weeks of application before a difference may be detected. However, there may be no noticeable difference. Controlled studies are not available to support this; the recommendations have developed through testimonials from horse owners."

It's thought that the addition of fat to the diet increases the amount of oil secreted by the skin's sebaceous glands. Says Herthel, "You end up with a higher oil content in the hair, which in turn makes it look better--an oily hair coat looks better than a dry hair coat." But Herthel is not particularly keen on giving oils by themselves. "Corn oil is a dense source of calories and does improve hair coat appearance, but it is bad for the horse's immune system and omega 3 to omega 6 (fatty acids) balance (see next section). By causing a severe imbalance of too much omega 6 to omega 3, chronic corn oil feeding can create horses that are more prone to inflammation and allergic diseases."

Philip J. Johnson, DVM, Associate Professor of Equine Internal Medicine at the University of Missouri's College of Veterinary Medicine, is also less enthusiastic about supplementary vegetable oils for the hair coat. "Healthy hair coat appearance can be changed to look more shiny with increased dietary oil (vegetable oils). In human beings, this leads to a greasy appearance that is not necessarily perceived as either healthy or desirable." He reiterates: "Healthy horses being fed a proper healthy ration do not need dietary supplements to enhance their hair coats. I do not believe that any supplements really do anything useful."

Some feel that a response to additional fat in the diet is indicative that these oils are lacking in the diet. "If your horse is on an adequate diet and receiving the amount of energy (fat) appropriate for his needs, I don't know that corn oil and other fat sources of themselves are going to make a discernable difference in hair coat quality," Raub states.

The disagreement in whether added fat makes much of a difference might arise in part from limited knowledge concerning all the nutritional requirements essential for the equine diet. Frederick Harper, PhD (equine nutrition), Extension Horse Specialist at the University of Tennessee, maintains a similar view. "From past experiences, it appeared that feeding corn oil to horses receiving very good rations did result in a shinier, brighter, glossier hair coat. However, the diet may not have been completely balanced, especially for all the trace minerals, vitamins, and amino acids. Our knowledge of all the nutritional requirements is not known, and we will likely see some changes in nutrient requirements if and when there is a new National Research Council Nutrient Requirements for the Horse." (The current version is online at

Vitamins And Trace Minerals--"Vitamin A, vitamin E, and biotin are some of the major vitamins that are commonly deficient in the equine diet," says Herthel, "as are the trace minerals silicon, zinc, and copper." He believes that while vitamins and trace minerals are usually found in sufficient amounts in green spring grass, they are often not available in adequate amounts in older hay/feed or stored hay/feed. "Some vitamins and essential oils become damaged by storage, heat, light, and processing. There is a good chance that certain trace minerals are deficient in oat or alfalfa hay and grain."

Omega Who?

A couple of nutrients receiving attention in the human and canine world have piqued interest in the equine world as well--the omega 3 and omega 6 essential fatty acids.

Omega 3 and omega 6 are recognized contributors to normal cell function and help prevent immune disorders, skin conditions, inflammatory conditions, and certain disease conditions. They also improve post-surgical recovery in canines, according to a Today's Breeder article ("Evaluating Essential Fatty Acids," Vol. 35, p. 14-16). But Ralston cautions, "The jury is still out on the omega 3 fatty acids. Horses do not have the same requirements as dogs. However, because we really don't know as much about horse requirements as we do for dogs, there may be some things they require that are normally provided in a well-balanced ration, such as essential fatty acids, that we don't know about yet."

Johnson agrees that there might be a role for supplemental omega 3 fatty acids in horses. "However, this is not specifically for the skin. Unlike dogs, horses do not commonly develop those types of skin problems that might be helped by omega 3 fatty acids. Nutritional omega 3 fatty acid supplementation might be useful for other, internal disease prevention for horses. However, it requires quite a substantial quantity of supplement to be given."

Herthel believes the jury is in when it comes to these fatty acids in the equine. "Every cell membrane is made up of these fats. So omega 3 is a normal component to the cell membranes. We think it improves cell membrane integrity and function and is a precursor to weak inflammatory mediators. Omega 6 is found in high amounts in corn oil; too much may lead to inflammatory disease because omega 6 is the precursor of really potent inflammatory hormones. The problem with the modern equine diet is there is too much omega 6 and not enough omega 3. If the horse is on a corn diet, it is getting way too much omega 6. By changing the balance more to what a horse would normally be getting in the wild, you decrease all kinds of inflammatory reactions whether it's of the intestines, lungs, skin, etc."

Another benefit of supplementing omega 3 might be prevention of laminitis. In a clinical trial, Herthel fed omega 3 fatty acids to one group of horses, then challenged that group and a control group with a starch overload designed to cause laminitis. "One hundred percent of the horses on the supplement didn't show any of the symptoms and 100% that were not on the supplement showed symptoms," he says.

Additionally, for the last several years Herthel has been supplementing many of the horses in his practice--including those undergoing surgery--with a multi-nutrient supplement he developed (Platinum Performance) that contains omega 3 along with vitamins and trace minerals. "It's changed our whole practice," he says. "We do a lot of surgeries, and when these horses' immune systems are stimulated with the right nutrients, they do extremely well. Using immuno nutrition not only gives a beautiful, healthy hair coat, but more importantly decreases healing times and decreases hospital- and stress-related complications. The end results are horses go home sooner because of anabolic and immuno nutrition."

Before You Supplement

The issue of supplementing a healthy horse might come down to whether one subscribes to the theory that a quality feed for the right age and lifestyle is truly nutritionally complete and well-balanced, or whether storage and processing of feed deprives the horse of necessary amounts of vitamins, minerals, and fats.

In Herthel's opinion, the only way a horse owner can be sure that a feed contains sufficient amounts of vitamins, trace minerals, and fats is to analyze the feed. "But that's pretty difficult and is not routinely done, so basically we just recommend an all-in-one supplement trace mineral, omega 3 and omega 6, amino acid, and vitamin supplement, because we know the diet is going to be deficient," he says. "We recommend a dose that generally would bring most any feed up to a level of normalcy. For a show horse, racehorse, or performance horse, we recommend supplementing pretty much year-round. For a pleasure horse used for spring and summer riding, we suggest supplementing just during that period of activity."

Herthel favors multi-nutritional dietary supplements over single nutrient supplements, which he says can be too hit-or-miss. Additionally, he says one can more easily overdose a horse on single nutrient supplements, but this is less likely with a multi-nutrient supplement.

Should you wish to supplement a horse, Herthel and others recommend first discussing this with a veterinary nutritionist or a veterinarian with nutritional training. This allows them to rule out other causes of poor hair coat (such as worms or skin conditions) and to make sure additional supplements won't cause additional problems.

"There's a tremendous amount of nutrition that affects the horse," Herthel explains, "and you can change the horse's whole health picture by what he is fed. You can also make it worse by feeding the wrong nutrients."

Says Ralston, "More is not necessarily better, and if the owner is supplementing minerals that are not needed, toxicities or adverse interactions could occur, especially when combined with other supplements."

Raub adds, "As soon as you start using individual supplements, you are potentially changing the balance of the diet. Minerals can affect one another and their ability to absorb a given mineral. For example, adding iron to the diet may cause reduced absorption of other minerals."

Whereas some veterinarians believe in routine supplementation, Raub joins those that don't--for now, anyway. "The issue of supplementation will always be there because people feel they need to do something for their horse. Horses were doing just fine for thousands of years without supplementing their diet with anything, although they didn't live and work as they do today. There are certain instances that may require some specific dietary needs--when the horse is engaged in high levels of activity and is really being pushed physiologically (such as the endurance horse during a race), or individual horses with specific medical problems. So I'm not dismissing all supplements. I'm saying they are marketed and presented in a light that really has not been shown to bear the brunt of research and to be shown as beneficial."


Myths About Supplementing

In their quest to do what's best for their horses, some owners fall prey to common fallacies regarding supplementation:

  • That a supplement can compensate for good grooming and poor-quality feed;

  • That the more expensive the supplement is, the better it will work, which isn't necessarily the case. Money is better spent on the best-quality hay and concentrates;

  • That if a little is good, more is better. In fact, more might be too much and result in a toxic reaction.

About the Author

Marcia King

Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.

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