PPID (Equine Cushing’s Disease)
What is it?
PPID (Pituitary Pars Intermedia Dysfunction), previously known as Equine Cushing’s Disease, is commonly encountered in older horses and ponies however, it is now also recognised in equines in their mid-teens.
The condition results from a pituitary gland adenoma (a benign tumour) which secretes abnormally high levels of adrenocorticotropin (ACTH). ACTH stimulates the production of cortisol (a type of steroid) from the adrenal glands. Therefore, high levels of ACTH result in an excessive production of cortisol (Hyperadrenocorticism).
- Thick, long, shaggy coat that is not shed (hyrsutism). Curly in advanced cases
- Excessive drinking and urinating (polyuria/polydipsia).
- Abnormal deposition of fat (crest, bulging of fat pads above eyes).
- Recurrent laminitis, due to high levels of cortisol in the blood Intractable pain secondary to laminitis represents the leading cause of euthanasia in Cushingoid horses.
- Increased susceptibility to infections (especially skin, foot abscesses, thrush) due to the immunosuppressive effect of circulating
- Muscle wastage in advanced cases. Drop-bellied/ ‘Pantomime’ horse
The most practical way of testing for Cushing`s disease in practice is a single blood test to detect ACTH levels.
There is no cure for Cushing`s disease, however there are some drugs available to help manage the disease.
Pergolide is, to date, the most effective medication available to lower ACTH levels and help to alleviate clinical symptoms of PPID. Pergolide is administered once daily and should be given for life after diagnosis of the disease. The dose can be adjusted in relation to individual response. Side effects (anorexia, depression are often transient and resolve after lowering the dose).
Husbandry is also very important in the managing of a horse(s) with PPID, Particular attention should be paid to diet, worming, oral hygiene/dental care, hoof trimming and prompt treatment of infection.
Horse(s) with PPID with long hair coat should be clipped during the warm season.
One of the most challenging complications which arises secondary to PPID is Laminitis. However, the medical therapy of PPID aims to bring patient comfort under control and decreases the likelihood of further bouts of laminitis.