Cushing’s Disease.

Always be mindful that Cushing’s Disease has a profound effect on a horse’s metabolism and body function. It requires a thorough veterinary assessment and laboratory workup to ascertain the extent of the condition and also whether there are any other medical conditions present as well. Management and treatment of any cushingoid horse should always be under veterinary supervision.

What is Cushing’s Disease?

It starts with the enlargement of the pituitary gland at the base of the brain – either through a benign tumour or hypertrophy through over activity which then starts a cascade of hormonal events throughout the body. The pituitary gland is a master controlling gland that sends out hormones to other glands in the body to keep metabolic and endocrine systems working properly. Most of the clinical signs of this condition are related to excess hormone from the pituitary gland affecting the adrenal glands near the kidney.

What are the clinical signs to watch for?

It generally occurs in older horses and ponies – usually they are at least 15 years old but can occasionally occur in young adults. They can have a coarse wavy coat which fails to shed in summer and excessive thirst and urination can be observed. They have a pot bellied appearance due to lack of muscle tone, are generally lethargic and they just don’t look well and healthy. There is general suppression of the immune system which leads to chronically poor healing of wounds and opportunistic infections in the mouth and elsewhere. Mares can become infertile and horses can become laminitic and diabetic.

How is it diagnosed?

The presentation of clinical signs as described above would lead to a suspicion of Cushing’s Disease which would then be confirmed by laboratory tests.

How is Cushing’s Disease treated and managed?

Any drugs that are given do not treat the pituitary condition itself but are used to manage the side effects of the pituitary condition. A thorough veterinary assessment of each individual case will lead to the best way to treat the condition. The prognosis for some horses will be excellent and they can be managed for some time. Other horses have a more severe presentation which will lead to a more guarded prognosis.

In addition to medication, a cushingoid horse must have good supportive care with regular effective worming, dental and hoof checks, and a good quality diet. The diet should be largely a roughage based diet with a multimineral vitamin supplement. Avoid feeding grains because there is a higher risk of laminitis and diabetes.

For further information about laminitis please visit our laminitis fact sheet on our website.