Rick Farr of Farr & Pursey Equine Vets shares his expert advice on Cushing's Syndrome
Q: “My 21-year-old has just been tested for Cushing’s (I’m still awaiting results). I know there are drugs that can be prescribed but wondered if anyone has any useful hints and tips on the best way to manage it and what signs to look out for? I am going to clip him as he’s quite hairy (hence the testing) and he gets sweaty just standing in the field. I prefer to keep him out as much as possible as he rubs so much when he’s in the stable. Any suggestions on feed supplements or even supplements to avoid please?”
A: Cushing’s Syndrome is an incredibly common condition in horses and can affect all horses and ponies at any age — however we tend to classically see it in our ever-growing geriatric population.
Unlike Cushing’s Syndrome in people and dogs, there are slight differences in horses, mainly due to the area where the problem arises. As a result, we try to more accurately term Cushing’s in our domestic horses as a Pars Intermedia Dysfunction.
In essence, Cushing’s Syndrome in horses is due to a tumour within the pituitary gland, which is a small gland found at the base of the brain.
As the tumour grows the pituitary gland produces increasing amounts of hormones; of these, our main focus is usually on one called adrenocorticotrophic hormone, or ‘ACTH’ for short. As ACTH increases it starts to affect other bodily systems, resulting in hirsutism (changes in the coat thickness and length), increased drinking and a subsequent increase in urination, lethargy, muscle loss/wastage and, as most people see it, an increased risk of laminitis and recurrent infections (quite often seen as tooth root infections/recurrent nasal discharges or slow healing wounds).
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So what can you do about Cushing’s? If you ever suspect the Syndrome it is best to test. This can be done at any time of the year, however we do know that there are increased levels of the hormone we look for during the autumn months (most labs now seasonally adjust their reference ranges for this change). There is increasing evidence to also show that if you treat these cases early with medication the overall long term prognosis with regards to stability also improves. All it requires is a simple blood sample.
Managing the Cushing’s case does not have to be hard. To be honest, it is just a bit of common sense. As I have stated, the biggest concern with the Cushing’s case is laminitis — therefore careful dietary management / high fibre diets / reduced calorie intake is always recommended. But, as we all know, this is applicable for all horses, whether they have Cushing’s Syndrome or not. Clipping affected individuals will also help, in addition to maintaining a level of exercise to help control weight.
When you scour the internet there are a plethora of “alternative therapies” on the market — however I would highly recommend avoiding them all all costs. When it boils down to it, the cause of the condition is a tumour. I therefore ask people if you had a tumour, which had been proven could be managed by medication and improve your quality of life, wouldn’t you take the medication?
The drug used to manage Cushing’s Syndrome in horses is called ‘Pergolide’ and, at present, there is only one licensed preparation within the UK for horses – ‘Prascend’. Initial doses may vary, and monitoring of the ACTH hormone is required in the early stages to help provide stability. The side effects tend to be small and transient and can be discussed at length with your vet if you are concerned.
As with most conditions there is no “magic pill”, however the vast majority of Cushing’s patients continue to live long and normal lives when the medication is used in conjunction with dietary management, exercise and general veterinary care.