Nutrients for Horses: What's Trending?

Learn how to derive the most benefit from popular equine nutritional supplements

Over the past 20 years the nutritional supplement industry has exploded, resulting in a plethora of powders, pills, pastes, and pellets labeled with claims to support equine health in varied ways. Published studies surveying horse owners together with an internet search of “equine nutritional supplements” show some of the most popular:

  • Antioxidants;
  • Hoof and coat supplements containing omega-3 fatty acids, proteins, biotin, and minerals;
  • Gastrointestinal supplements for gastric ulcers and hindgut health;
  • Pre- and probiotics;
  • Muscle builders;
  • Calming supplements;
  • Products for cough, allergies, and respiratory health;
  • Joint and tendon supplements; and
  • Electrolytes.

Study results indicate that electrolytes and joint supplements reign supreme, serving as the most widely used nutritional products for horses in both the United States and United Kingdom.

“Discipline also appears to dictate which supplements ‘should’ be used,” adds Sarah Freeman, BVetMed, PhD, professor of veterinary surgery at the University of Nottingham’s School of Veterinary Medicine and Science, in the U.K.

For example, Freeman says that in her experience electrolytes are popular in eventing, whereas behavior supplements are commonly used in dressage. 

Carey Williams, PhD, an equine extension specialist at Rutgers University, in New Brunswick, New Jersey, and Amy Burk, MS, PhD, professor and extension horse specialist at the University of Maryland, in College Park, surveyed top-level event riders over a two-year period. In their 2012 study they relayed that electrolytes were the type of oral supplement administered most, followed by salt and joint supplements. The average number of supplements owners fed competing horses on a regular basis was approximately four.

Considering nutritional supplements’ popularity in the face of age-old questions regarding their efficacy and safety, we’ll review some of the trendy nutritional supplements in the equine industry, the rationale for their administration, and scientific data supporting their use.

One of the main messages Freeman says she’d like owners to keep in mind during this discussion is that horses don’t break down products in their gastrointestinal system like other species, such as humans and dogs, do.

“This means that you can’t just take evidence from human literature and assume it will then work in the horse,” she says. “Products that work in another species may not—and we know some do not—work in the horse.”

4 Popular Products

Resveratrol

This compound can be isolated from more than 70 plant species, including cranberries and grapes. Proponents say resveratrol offers an array of health benefits for humans and animals as a result of its anti-inflammatory and antioxidant properties. Marketing materials suggest that resveratrol could reduce the use of non-steroidal anti-­inflammatory drugs such as phenylbutazone (Bute), which in some circumstances causes gastrointestinal upset/ulceration and kidney problems in horses.

Examples of human conditions resveratrol might benefit include cardiovascular disease, cancer (due to its anti-tumor activity), diabetes, obesity, metabolic syndrome, hypertension, stroke, neurodegeneration, age-related diseases, and inflammatory diseases.

Considering this “grocery list” of conditions that resveratrol appears to be useful for in humans, the evidence supporting its use is sparse and inconsistent. Further, researchers studying humans state, “… resveratrol application is still … a major challenge for the pharmaceutical industry, due to its poor solubility and bioavailability, as well as adverse effects” (Salehi B et al., 2018).

A handful of resveratrol studies conducted in horses have been published, as outlined here by Kirstie Pickles, BVMS, MSc, PhD, CertEM(IntMed), Dipl. ECEIM, MRCVS, of Chine House Veterinary Hospital, in Sileby, U.K.

1. Client-owned performance horses with lameness localized to the lower hock joints received triamcinolone (a corticosteroid anti-­inflammatory drug) injections in both hocks. Researchers (Watts AE et al., 2016) then divided the horses into two groups; one received oral resveratrol for four months and the other received a placebo and served as the control. Based on owner-­reported responses to treatment, more horses in the resveratrol group than controls were less lame after four months. That said, the researchers noted no difference between subjective lameness scores in the two groups.

2. Resveratrol had an anti-inflammatory effect on cultured equine cartilage cells in a lab at low doses. As they increased the resveratrol dose, researchers (Ryan DJ et al., 2017) noted pro-inflammatory and even cytotoxic (cell-killing) effects. “These findings suggest that resveratrol could have a narrow therapeutic index of safety,” says Pickles.

3. To find an alternative or supplemental method of controlling inflammation in horses, Missouri researchers (Martin L et al., 2020) collected blood samples before and three weeks after supplementing horses with either a commercially available resveratrol product or a placebo. They analyzed those samples for inflammatory mediators and other measures of inflammation and noted no changes in any of the parameters.

“This study shows that the particular commercially available product was no use but that resveratrol itself may still be worth it given that other studies show it could be beneficial,” Pickles says.

Grapeseed extract (GSE)

Grapeseed extract contains compounds believed to offer health benefits. Examples include polyphenolic compounds (in addition to resveratrol), proanthocyanidins, anthocyanins, and flavonoids that together apparently exert both antioxidant and anti-inflammatory effects in animals.

Few researchers have evaluated grapeseed extract in horses. In a 2009 study JA Davies et al. looked at grapeseed extract’s effect on “general health, intake, and digestion.” They found that GSE “could have important implications for the prevention of hindgut acidosis.” Pickles cautions that the study included only four horses and lacked a control group.

​This article continues in the July 2020 issue of The Horse: Your Guide to Equine Health Care. Subscribe now and get an immediate download of this issueincluding this in-depth article on how to derive the most benefit from popular equine nutritional supplements.

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