Nutritional Deficiencies

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Also Known As

Lack of essential nutrients


Nutritional deficiencies in horses take on many forms and signs of deficiencies are often nonspecific. Diagnosis is often complicated by disease and deficiencies of several nutrients simultaneously. Unfortunately thorough studies of equine nutritional deficiencies are lacking in many areas.

When a horse is not provided the required nutrients, the result may be disease, poor exercise capability, susceptibility to parasites and bacterial infections, dental problems, and development of metabolic stereotypies.

Although some horses appear to be in good health, and, in fact, may be overweight, nutritional deficiencies may lead to health problems. Although overfeeding is often a contributing factor when horses put on too much fat, nutritional deficiencies may play a part in the regulation of the horse's appetite.

Loss of weight or failure to thrive indicate nutritional deficiencies related either to caloric intake or the body's poor utilization of the feed and are marked by a decrease in fatty tissue and muscle of the horse.

In foals or young horses, growth of the skeleton may slow or stop. In adult horses, osteoporosis may affect the bone structure. If the horse reaches a point of actual starvation, the internal organs are affected, as well as the immune system, reproduction, and energy efficiency.

Horses fed a diet of poor-quality hay are subject to protein, mineral, and vitamin deficiencies, metabolic disorders, parasites, and bacterial and viral infections, in addition to lack of exercise capability and the general well-being that affects a horse's interaction with owners/handlers and other horses.

Some horses have metabolic problems, diseases, or intestinal disorders that keep them from getting adequate nutrition from their diet. One of these conditions, Dysbiosis, is also known as "Leaky Gut Syndrome." The gastrointestinal tract becomes eroded and ulcerated, impairing nutrient absorption, which, if undetected, can lead to severe malnutrition, as well as bacterial and viral infections and diseases. .


  • Chronic weight loss
  • Chronic diarrhea
  • Scruffy coat
  • Susceptibility to disease and infection
  • Indications of tight or sore muscles
  • Lack of exercise or work capability
  • Orthopedic problems
  • Parasites
  • Colic
  • Dental problems


Very few studies have been done to examine the complex issues related to nutritional deficiencies in horses. .

Horses eating good quality pasture or hay generally take in all the nutrient energy they need from forage. Unfortunately, many fields producing hay are overworked to the point that the hay does not contain all the natural vitamins, minerals, proteins, bacteria, and enzymes necessary for a healthy horse.

In addition, a number of businesses have sprung up making processed horse feed with many additives and offering feeding alternatives that are easy to obtain, but that do not compare to a healthy diet of well-grown hay and natural grain products.


Understanding what constitutes adequate healthy nutrition, where to get high-quality feed and supplements, and how to read feed tags for pertinent information will help horse owners prevent nutritional deficiencies.

It is important to be knowledgeable about the best hay, grain, and supplements available in a particular area. In addition, horse owners and handlers need to determine feeding requirements for individual horses based on age, climate, level of work and exercise, lactation or pregnancy, and general health.

Horses should be fed regularly and given access to food more than twice a day to keep their digestive systems working as nature intended. Look for problems at feeding time and make sure horse's teeth are sound. Avoid feeding overly-processed, sweetened, moldy, musty, dusty, or frozen feed.

Make sure horses have a plentiful supply of fresh water available at all times. Be observant of the horse's manure, since a change in manure color, odor, or quantity may indicate problems that could be linked to nutritional deficiencies or problems.

Gradually decrease the caloric intake of horses that have become fat or obese. Advice from a veterinarian who is knowledgeable about good equine nutrition, including diet, feeds, and supplements is important.


A nutritionally complete diet for a horse will contain these ingredients: water, energy, fiber, protein, carbohydrates, fatty acids, minerals, and vitamins.

An unlimited supply of fresh, clean water that is accessible to the horse at any time, except immediately following exercise during the cooling-down time, is crucial for well-being and proper utilization of feed. If any question exists as to the suitability of water in a given situation, it should be tested to make sure it does not contain toxic material or infectious organisms, such as salmonella.

Treatment of nutritional deficiencies depends on diagnosing the deficiency. This may be a difficult task, but the deficiency will usually fall into one or more categories. Lack of energy is often a sign of inadequate caloric intake from a well-balanced diet or from poor utilization of the diet.

Consultation with a veterinarian to determine if any underlying disease is contributing to the lack of energy is often necessary. For example, if the horse has an unhealthy digestive tract that is ulcerated or damaged in some way, antibiotic therapy may be a prerequisite to healing the tract.

Once the digestive tract is healed, a supplement with enzymes and food for the normal bacteria to flourish needs to be given until the effects of the antibiotics on the immune system are mitigated and the digestive system returns to normal. .

Planning a diet that is known to contain enough calories, along with vitamins, minerals, and enzymes will help overcome the nutritional deficiencies.

Mineral deficiencies are common in growing horses or lactating mares fed poor-quality hay or pasture. At least 21 minerals are required in an adequate horse's diet. The most important minerals are calcium, phosphorus, salt, and in some areas, selenium. .

Copper and zinc are essential and are usually found in average or better quality feeds and in trace-mineralized salt. Following the best nutritional guides available for horses and working with a knowledgeable veterinarian will help ensure that each horse's nutritional needs are met to maximize both health and work/exercise capabilities.

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EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.