Dietary intervention in selenium imbalances: a case series

Selenium is a critical trace element for equine health, involved in metabolic processes and antioxidant defense. However, imbalances in selenium intake can lead to health issues such as deficiency or toxicity. This article examines two different cases: five mares displaying reported clinical signs of interrupted ovarian activity, polyuria/polydipsia and weight loss, and a Quarter Horse stallion with reported neurological clinical signs. The mares were housed in the same stable and fed the same hay and pasture but received concentrates with varying selenium levels. Blood tests indicated elevated plasmatic selenium levels, suggesting selenium imbalances. Clinical signs were resolved by implementing an exclusion diet, and all mares resumed breeding within 3 months. In the second case, a 9-year-old Quarter Horse stallion presented with neurological clinical signs (tremors and shivering) and was referred for nutritional consultation. Plasma selenium levels confirmed selenium deficiency, as indicated by the referring clinician. The horse's diet was balanced and adjusted as required, and an initial supplement of selenium and vitamin E was added. After 28 days, with follow-up evaluations, the horse's selenium status improved, and the supplement was reduced. This underscores the importance of managing selenium intake carefully, considering environmental factors, the form of selenium supplementation and long-term health to ensure optimal health in horses. Selenium content in concentrates, forages and water should be carefully considered in all cases of suspected selenium imbalances, ensuring optimal selenium inclusion levels that do not exceed the established limits.