This condition, caused by an unbalanced diet, can have serious musculoskeletal implications for affected horses. | Photo: Courtesy Dr. Rubén Anguiano

By Rubén Anguiano, MVZ, MSc, WEVA Regional Ambassador—México and Central America
Universidad de Guadalajara and Los Alamitos Equine Hospital, Guadalajara, México

Nutritional secondary hyperparathyroidism (NSHPT) is an uncommon endocrine pathology also known as “bran disease, Miller disease, big-head disease, osteitis fibrosa, swollen face disease, and equine osteoporosis.”

Horses that consume a diet low in calcium and/or high in phosphorus (typically with a phosphorus-to-calcium ratio of 3:1 or higher) can develop NSHPT. Horses that ingest grasses and toxic plants containing high concentrations of oxalate compounds, which inhibit calcium absorption, can be predisposed to developing NSHPT