Managing and caring for a persistently underweight horse can be difficult and frustrating for the owner and/or caretaker. A number of factors can be involved or contribute to the condition. A primary and initial evaluation should focus on the basics of nutrition. Ascertaining the animal’s appetite, the quality of feed provided, and the available quantity can help determine whether there is nutritional inadequacy that can be corrected. Caloric supplementation may be all that is required to regain and maintain adequate body condition. Addition of corn oil, a fat supplement, or another calorically dense feed may meet this need. For older horses, after an oral examination has ruled out significant dental problems, switching to a more easily digestible feed formulated for older horses may be warranted.

Another factor that might lead to inadequate caloric or nutrient intake could be activity or stress that exceeds the horse’s diet. A feed analysis and a reduction in stress and/or activity might be necessary. The next consideration is that of gastrointestinal parasitism, including the possibility of the presence of larval stages of the parasites and/or encysted stages of small strongyles (cyathostomes) that are prohibiting the animal from thriving. A good oral examination should also be performed to rule out problems related to the horse’s mouth and/or dentition. This becomes a significant consideration in aged horses that have worn and erupted the full extent of their dentition and no longer have teeth capable of occlusion or mastication of feeds. Such instances might require “slurry diets” to ensure adequate nutrition. Furthermore, such horses with poor dentition may be at greater risk for esophageal choke and colic due to poor mastication. Horses in regular performance or in stressful situations such as overcrowding may suffer from gastrointestinal ulceration. Medical therapy of such conditions using specific anti-ulcer medications is effective in resolving clinical signs and pathology caused by gastrointestinal ulcers. Feed digestibility can become a significant factor in older horses. Therefore, feed changes to a more digestible diet such as commercially produced geriatric feeds may be necessary.

Once feed analysis has been fully evaluated, other causes of poor condition must be considered. Chronic disease conditions, chronic causes of colic or malabsorption, and gastric and duodenal and/or colonic ulceration should be considered. Evaluating horses for such conditions may become difficult and costly. Such evaluation will require veterinary intervention and evaluation.

Editor’s Note: This is from Understanding Equine Preventive Medicine by author and veterinarian Bradford G. Bentz, VMD