What is Equine Cushing’s disease?
Equine Cushing’s Disease, which is more correctly known as Pituitary Pars Intermedia Dysfunction (PPID), is a complex hormonal condition caused by dysfunction of a gland called the pituitary gland, which lies at the base of the brain.
Although the cause of the condition is not completely understood, it is thought that as part of the ageing process some horses develop enlargement of part of the pituitary gland (the pars intermedia), which produces excessive hormones that are important in controlling various body functions. These hormones are known as POMC hormones (pro-opiomelanocortin-derived peptides) and include MSH (melanocyte stimulating hormone), CLIP (corticotropin-like intermediate lobe peptide), beta endorphin, and ACTH (adrenocorticotrophic hormone). As the abnormal functioning of the gland produces an excessive amount of a range of different hormones, clinical signs can be variable from horse to horse.
What horses are affected?
Although typically considered to be an older horse disease, affecting horses over 20 years old, cases as young as seven have been diagnosed and PPID should be considered in any horse showing the typical clinical signs.
What are the clinical signs?
The most consistent and obvious clinical sign is hirsutism, or the presence of an abnormally long and curly coat. Although this is not seen in every case, its appearance is typical. The classical curly coat is often preceded by years of late shedding of the winter coat.
The most clinically relevant and serious clinical sign of PPID is laminitis. It is thought that over 80% of horses with laminitis have the disease as a result of a hormonal abnormality, most commonly PPID. It is therefore important that any horse with laminitis is tested for PPID as a matter of course. Getting the PPID under control is an important part of the management of affected cases.
Other clinical signs include increased drinking and urination, lethargy, weight loss, muscle loss, excessive sweating, and poor performance. Many horses have a bulge above their eyes due to unusual fat deposition. Severely affected horses can have reduced immunity and are prone to recurrent infections such as foot abscesses, tooth root abscesses, and other secondary infections. They may also take longer to heal from problems such as minor wounds and may develop liver disease.
How is PPID diagnosed?
PPID can be diagnosed by a simple blood test in the vast majority of cases. In less obvious cases, especially in younger horses that are just developing the disease, a more complex type of test needs to be completed looking at changes in hormone levels in response to the injection of certain hormones.
How is PPID treated?
Excellent control of the vast majority of cases is achieved with treatment with Pergolide (Prascend) alongside lifelong routine care including a suitable worming program, teeth care, foot care, and vaccinations.
Your veterinarian is the best person to discuss the disease and its potential effects on your horse or pony; please do not hesitate to contact the practice to discuss this in more detail.
Can I prevent PPID?
Unfortunately, there is no way to prevent your horse or pony from developing PPID. However, with readily available blood tests we can detect and treat cases far earlier and more effectively, leading to many years of a good quality of life.
For further details please see: www.talkaboutlaminitis.co.uk
