Endocrinopathic Laminitis and Equine Metabolic Syndrome

Abstract

A common feature of equine laminitis is the dysfunction and failure of the dermal-epidermal attachment between the hoof wall and the distal phalanx, resulting in compromised digital support. Conditions that cause insulin resistance (IR) in horses, including obesity, equine metabolic syndrome (EMS), and pituitary pars intermedia dysfunction (PPID), greatly increase the risk of endocrinopathic laminitis (EL). Equine and human metabolic syndrome share some common features, including insulin resistance, regional adiposity, a pro-inflammatory state, and inflammatory and degenerative co- morbidities, with laminitis being the predominant co-morbidity in the horse. Epidemiological studies have identified many negative effects of IR and obesity on conception and pregnancy outcome in women. Studies are needed to determine the effects of IR on equine fertility. Broodmares might be at particular risk for EL due to the physiological decrease in insulin sensitivity associated with pregnancy. Previous laminitic episodes, insulin resistance due to obesity, EMS, or PPID, painful or stressful conditions, septic conditions, lack of exercise, exogenous corticosteroid administration, grazing high fructan content pasture, and high glycemic index feed supplementation should all be considered potential risk factors for EL that could have an additive effect with pregnancy-associated IR to push mares over the hypothetical insulin concentration threshold for laminitis induction. Strategies for the management of at-risk mares include diagnosis and treatment of EMS and PPID, weight and glycemic response management through diet and exercise, and therapeutic hoof trimming for mares with stable chronic laminitis. Mares with unstable chronic laminitis and/or inadequately controlled IR should be considered unfit for breeding. [...]