Modern management of chronic endocrine disorders in horses : PPID & EMS

The challenge, therefore, lies in what precedes laminitis. Pituitary Pars Intermedia Dysfunction (PPID) and Equine Metabolic Syndrome (EMS) often progress silently, remaining undetected until laminitis becomes the first obvious clinical sign.

In an aging, increasingly obese and less active horse population, this diagnostic delay is becoming the rule rather than the exception. The need for more reliable diagnostic tools to detect these disorders before laminitis strikes has never been greater.

Equine Cushing’s: a chronic disease that needs lifelong monitoring

Pituitary Pars Intermedia Dysfunction (PPID), also known as equine Cushing disease, is an endocrine disorder caused by an abnormal activity of the pituitary gland. The condition results from hyperplasia of the pars intermedia, leading to excessive production of adrenocorticotropic hormone (ACTH). Elevated ACTH disrupts normal metabolic processes and weakens immune function, contributing to a wide range of clinical signs in horses. Measurement of ACTH concentrations remains the primary biomarker for both diagnosis and ongoing disease management.

PPID is a chronic and progressive disease requiring lifelong management. Although treatment with pergolide can effectively control ACTH secretion, dosage requirements often change over time. Reliable monitoring of ACTH levels is therefore essential to ensure each horse receives the appropriate dose. Inadequate dosing may result in under-treatment, leading to worsening clinical signs or laminitis, while over-treatment can cause adverse effects. Regular testing supports optimal disease control and helps maintain the horse’s long-term health and well-being.

Equine Metabolic Syndrome : A complex, multifactorial and evolving metabolic disorder

Insulin dysregulation elevated basal insulin concentrations or as an exaggerated post-prandial  is the defining feature of Equine Metabolic Syndrome. It may present as an exaggerated post-prandial insulin response following carbohydrate intake or a high basal insulin level. Importantly, basal insulin levels alone may underestimate the severity of the condition in some horses. A major challenge in EMS lies in the individual variability of insulin responses. Insulin concentrations are influenced by diet and sampling conditions, complicating interpretation. For this reason, reproducible and reliable insulin measurements are essential to accurately identify affected horses and to monitor metabolic evolution over time, particularly the insulin response following carbohydrate intake.

EMS is strongly associated with identifiable risk factors, including predisposed breeds or phenotypes, energy-dense diets, and insufficient physical activity. Modern management practices have amplified these risk factors, contributing to the rising prevalence of the syndrome and to an increasing number of laminitis cases linked to metabolic dysfunction.

EMS requires long-term management focused primarily on dietary control and exercise, which remain the cornerstone of treatment. In some cases of marked hyperinsulinemia or active laminitis, veterinarians may introduce pharmacological support such as SGLT2 inhibitors (gliflozins), drugs initially developed for human diabetes. These molecules can rapidly lower circulating glucose concentrations and help stabilize insulin status. They are generally used during the acute phase of metabolic instability and are progressively withdrawn once insulin levels are controlled and management measures are effective. Even when pharmacological support is discontinued, strict dietary management must be maintained to prevent relapse. Regular insulin monitoring therefore remains essential.

Why reliable endocrine diagnosis changes everything

In PPID and EMS, clinical signs alone are insufficient to guide diagnosis and long-term management. In vitro diagnostic is therefore central to decision-making, from early detection to treatment adjustments and laminitis risk assessment. Acting early depends on the ability to identify hormonal dysregulation as soon as suspicion arises and to rely on test results with a high level of confidence and precision.

Endocrine assays are particularly sensitive to pre-analytical and biological variability. Stress, transport and feeding can significantly influence hormone concentrations, especially ACTH, which is inherently unstable. In practice, the risk is not only missing a diagnosis, but acting on a result that does not truly reflect the horse’s endocrine status. In addition, physiological seasonal variations in ACTH require the use of seasonally adjusted reference values. Without robust and standardized assays, results may be difficult to interpret and potentially misleading.

When basal results fall into an intermediate or equivocal range, dynamic confirmation protocols are essential to refine diagnosis. In PPID, a basal ACTH measurement provides a robust first-line assessment, while a TRH stimulation test offers additional insights into pituitary activity in early or evolving cases. In EMS, basal insulin concentrations reflect resting metabolic status, and an Oral Sugar Test complements this evaluation by assessing the post-prandial insulin response, which is closely associated with laminitis risk. Using standardized protocols and validated reference values strengthens diagnostic confidence and supports consistent, informed decision-making over time.

Importantly, results must always be interpreted in light of the horse’s clinical status. Hormonal values should not be considered in isolation but integrated with clinical findings and risk factors. Reliable, precise assays combined with thoughtful clinical interpretation remain the foundation of sound endocrine decision-making in equine practice.

Long term follow-up : The real key in chronic diseases

Effective management of PPID and EMS does not stop at diagnosis or treatment initiation. Long-term follow-up is the cornerstone of success in these chronic conditions, requiring both consistent clinical observation and structured biological monitoring.

Clinical monitoring remains essential and should focus on body condition, early signs of laminitis, susceptibility to infections, and behavioral or performance changes. Subtle variations often precede biological deterioration, and consistency in clinical observations over time is critical to detect meaningful trends rather than isolated events.

To ensure meaningful interpretation of results over time, the same analytical method should always be used. Consistency in testing improves result comparability, supports accurate therapeutic adjustment and ultimately strengthens long-term clinical decision making.

Toward proactive endocrine management in equine medicine

PPID and EMS are lifelong endocrine disorders in which delayed diagnosis can lead to severe laminitis. Early detection and structured follow up are therefore essential.

Effective management relies on consistent ACTH and insulin testing, interpreted within the context of each individual horse, alongside clear owner communication and long term monitoring. In chronic endocrine disease, precision and consistency are what ultimately protect the horse.