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Veterinary supervision is critical for the safe management and treatment of any horse with Cushing’s Disease.
Cushing’s begins with enlargement or overactivity of the pituitary gland, a small but powerful gland located at the base of the brain. This can be due to a benign tumour or hypertrophy (overgrowth) of tissue. The pituitary gland controls hormone release throughout the body, and when it becomes overactive, it triggers a cascade of hormonal imbalances, especially involving the adrenal glands.
The excess hormones, particularly ACTH (adrenocorticotropic hormone), lead to the wide range of symptoms seen in horses with Cushing’s Disease.
Cushing’s is most commonly diagnosed in horses aged 15 years and older, though it can occasionally appear in younger adults.
Some of the most recognisable signs include:
One of the most important aspects of managing Cushing’s is controlling blood sugar and insulin levels. Many horses with Cushing’s Disease also develop insulin resistance, making them extremely sensitive to high-NSC feeds, such as grains and sugary treats. These feeds can increase the risk of laminitis and metabolic crashes. To learn more about the connection between high NSC feeds and insulin resistance, visit:
Feeding pregnant mares diets high in non-structural carbohydrates (NSC) , such as large amounts of grain, sweet feeds, or lush pasture can have long-term effects on both the mare and her foal. Excess NSC leads to repeated spikes in blood glucose and insulin, which can cause the mare to develop insulin resistance during pregnancy. This metabolic imbalance not only impacts the mare’s health but also influences the developing foal through altered nutrient and hormonal signalling in the womb.
Insulin resistance in pregnant mares can affect placental function, leading to an increased risk of foals being born with impaired glucose metabolism. These foals may have reduced insulin sensitivity from birth, making them more susceptible to metabolic syndrome and other endocrine disorders later in life. Early hormonal disruption during the developmental phase can permanently influence how the foal’s endocrine system responds to sugar and stress.
One long-term consequence of this altered metabolism is a higher risk of early-onset Cushing’s-like disease (PPID) in young horses. When insulin resistance persists, it can contribute to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, leading to elevated cortisol levels. Over time, this can cause degeneration of the pituitary gland, accelerating the onset of PPID , a condition more commonly seen in aged horses but increasingly recognised in younger animals.
Preventing these issues starts with feeding management during pregnancy. Providing a low-NSC, fibre-rich diet with controlled energy intake supports steady blood sugar levels, maintains insulin sensitivity, and promotes healthy foetal development. Using feeds such as soaked beet pulp, chaff, or coconut meal (copra), combined with balanced vitamins and minerals (Equilibrium Mineral Mix) , helps reduce metabolic stress on the mare and lowers the risk of passing metabolic vulnerabilities to the next generation
Veterinarians will usually suspect Cushing’s based on a horse’s clinical signs. Diagnosis is then confirmed with blood tests, such as ACTH testing or the TRH stimulation test. It’s also important to check for concurrent conditions, such as insulin dysregulation or infections, which can influence the treatment plan.
There is no cure for Cushing’s Disease, but the condition can be successfully managed with medication and proper care. Medications such as pergolide (Prascend®) help reduce ACTH levels and stabilise hormonal activity, improving symptoms and quality of life.
A comprehensive management plan should include:
Cushing’s Disease is complex but manageable with the right approach. Recognising early signs, working closely with your vet, and making targeted nutritional changes, especially avoiding high-NSC feeds, are key to long-term health and comfort. If your horse shows symptoms or is at risk, act early to give them the best possible outcome.
