Ask three horsemen about the role of supplements in a horse’s diet and you likely get three different answers. As the number of available products has grown over the past two decades, so too has the debate over how and when they are best utilized.
Yet one rule is universally recognized: “Give only what a horse needs.” Every veterinarian and nutritionist will tell you that unnecessary or overzealous supplementation isn’t only a waste of money, it can lead to nutritional imbalances. For instance, a horse given a vitamin supplement in addition to a grain fortified with vitamins may ingest an overdose of certain nutrients, which can be detrimental to his health. Its much much safer and more effective to first identify your horse’s dietary needs and then shop for a supplement that meets them.
The tendency to reverse this order is understandable. If your friend’s mare looks fabulous after being started on a particular supplement, for instance, it’s tempting to put your own horse on it. The mare, however, may have been missing something in her diet or had a specific problem that your own horse does not. In that case, you won’t see the same benefits. In fact, your horse may have a different deficit or need that only a different supplement can address.
Fortunately, supplements are available to address nearly every problem a horse can have, from poor-quality hooves to creaky joints to excitable behavior. Here’s a survey of the basic categories of equine supplements available, along with a rundown of the ingredients you are most likely to find in each one. Once you’ve had a look, discuss your horse’s needs with your veterinarian and get ready to go shopping.
Calming supplements
Which horses may benefit: those who are fractious or “difficult” even after a veterinarian has ruled out pain, ill-fitting tack and other physical problems that may lead to uncooperative behavior. Calming supplements are intended to “settle” these horses with nutritional and herbal ingredients that affect the nervous system.
Common ingredients:
- magnesium, a mineral that plays a role hundreds biochemical reactions within the body, including muscle and nerve function
- thiamine (vitamin B1), a compound found in fresh forages that helps the body convert carbohydrates and fat into energy and is critical to proper function of the nervous system.
- valerian, an extract from the dried root of the flowering plant Valerinana officinalis, which contains compounds believed to interact with certain neurotransmitters; used since the times of the ancient Greeks to relieve restlessness, anxiety and insomnia
- chamomile, an extract derived from the flowers of the perennial herbs Matricaria recutita or Chamaemelum nobile; used for thousands of years to treat insomnia and anxiety
- L-tryptophan, an amino acid that is a precursor to the neurotransmitters serotonin, which induces calming and melatonin, which encourages sleep
- taurine, the organic acid abundant in animal tissue that plays a significant role in many neurologic functions
- inositol (vitamin B8), an organic compound integral to the health of cell membranes; research suggests that inositol supplementation can aid in treatment of panic disorders, bipolar depression and obsessive-compulsive disorder in people
- raspberry leaves, the dried foliage of the raspberry bush are high in vitamin C, tannins and other nutrients; long thought to affect muscle tone
Special considerations: Many sport and show associations restrict the use of some calming agents prior to competition. If your horse competes, check with any governing body for guidelines.
Joint-care supplements:
Which horses may benefit: those in the early- to mid-stages of arthritis or otherwise at risk because of injuries, “mileage” or old age. Joint supplements aim to support the health of structures such as the cartilage between bones and the synovial fluid in the joint spaces.





