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Equine Cushing’s disease

Equine Cushing’s disease, or pituitary pars intermedia dysfunction (PPID), is common in older horses and is suspected when a horse shows the classic signs of a long, thick hair coat that refuses to shed.

Horses with Cushing’s disease may also have abnormal fat deposits, increased thirst and urination, a lowered resistance to disease and a tendency to develop laminitis more easily than healthy horses.

Dietary recommendations will be dependent on the horse’s body condition, the presence of insulin resistance (IR) and adrenocorticotropic hormone (ACTH) levels, which can be determined by a veterinarian. In early stages of the disease, horses showing signs of Cushing’s do not always have test results that confirm the illness, leaving owners unsure of how to manage horses.

The following are nutritional guidelines for horses that have been diagnosed with Cushing’s or are displaying early signs of the disease.

    • All PPID horses should be fed a primarily forage diet that will maintain (or regain) ideal body condition and avoid obesity which will worsen IR.
    • Restrict horses from pasture at times of the year when it is high in sugars.
    • Feed concentrates with a low glycemic index (GI) as required to maintain body condition at around 2.5–3 on the 0–5 body condition score index.
    • Feed small, frequent meals to avoid major deviations in glucose and insulin concentrations.
    • Super fibres such as beet pulp or soy hulls are excellent low-GI feeds for horses with PPID (eg. McMillan Grain Free).
    • Feeds containing greater than 3 percent molasses and20 percent non-structural carbohydrate (NSC) should be avoided if there is evidence of IR.
    • Pellets or extruded feeds that are higher in fibre (> 10 percent) and fat (> 5 percent) such as NRM LGI Sport or McMillan Grain Free should be fed instead of sweet feeds to provide additional dietary energy. Beware of senior feeds that could contain high amounts of NSC or molasses.
    • Meet nutritional requirements in overweight horses with balancer pellets such as NRM Equine Balancer to provide nutrients with limited calories.
    • Use low-GI full feeds such as NRM Low GI Sport or NRM Evolve for underweight horses.
    • Fat sources such as KER Equi-Jewel, sunflower seeds or oil can also be included in diets to increase body condition if required.
    • Feed long-chain omega-3 fatty acids from KERx EO-3 for a glucose regulating and anti-inflammatory effect without increased calorie intake. Use 60–120ml/500kg.
    • Stabilise hindgut pH and bacterial populations by limiting fructan intake from pasture and supplementing with a hindgut balancer such as KERx EquiShure.
    • Combat oxidative stress by antioxidant supplementation with natural vitamin E KERx Nano E.
    • Feed Equin Hoof Food or KER Bio-Bloom to increase hoof growth and allow more rapid hoof reshaping after a laminitis episode.
    • Give the horse access to rock salt or a salt block.
    • Small amounts of chaff or soaked beet pulp/soy hulls may be mixed with supplements to increase palatability and encourage consumption.


For further assistance and advice on feeding horses with Cushing’s, consult a qualified Equine Nutritionist.

Article supplied by Luisa Wood, Equine Nutritionist.