What Causes Cushing’s?
Cushing’s disease (also known as Pituitary Pars Intermedia Dysfunction -PPID), is an endocrinopathic disorder (hormone dysfunction), mainly affecting older horses. A portion of the brain, the hypothalamus, loses its ability to inhibit dopamine (a neurotransmitter), and this results in excessive, sometimes abnormal growth of the pituitary pars intermedia and an increase in the secretion of hormones and hormone-like factors from the pituitary gland.
One of the hormones secreted is ACTH (adrenocorticotropin hormone), which results in the commonly recognized clinical signs of PPID.
The most obvious symptom of Equine Cushing’s is a hairy coat. Insulin dysfunction, coupled with cortisol production causes an increase of amino acids into protein and the dysfunction of the melanocytes results in a paler coat. At the same time, diversion of amino acids to hair production can lead to muscular wastage, weight loss and pot bellies. The hormonal disruption leads to symptomatic fat deposits, cresty neck etc., as well as increased appetite and water intake.
Cortisol dysfunction also affects the kidneys resulting in higher urinary output, whilst the dopamine interaction leads to lethargy, docility and behavioural changes.
Other signs include chronic laminitis, excessive sweating, wounds not healing quickly, increase in skin infections and susceptibility to internal parasites. Contact a vet directly to come and diagnose.
The disease is one of the most common endocrine disorders in horses and ponies. Most commonly seen in older horses and ponies, however younger equines can be susceptible.
Finally, non-specific inflammation and insulin resistance can increase the incidence of laminitis.
How to prevent a horse getting Cushing’s
Unfortunately there isn’t a fool proof way to avoid the disease, but there are precautions owners can implement to lower the risk – nutrition.
Keep your horse or pony in the correct condition and not over weight. Sugar should be minimal and pay close attention to the good-doers.
What to feed a horse with Cushing’s?
There is no cure for Cushing’s syndrome, but with careful management, the correct nutrition and veterinary treatment, most horse and ponies can live comfortably for several more years.
The nutritional management is very similar to feed the laminitic horse or pony – high fibre, low non-structural carbohydrate diet and maintaining a healthy body condition score. This means low starch/sugars/fructans of sugar in grass.
Choosing fibre based feeds, low in starch and sugar is a good start as the base for feed. Complementing with a balancer, is an ideal way to ensure suitable levels of vitamins, minerals and quality protein are included, that doesn’t contribute to excess calories (starch and sugar). Talk to a qualified nutritionist for advice on what feeds are suitable to be paired with your fibre base.
Avoid cereals and mixes which are high in starch – if fed in excess these feeds can cause weight gain.
Speedi-Beet and Fibre-Beet are super fibre, beet pulp feeds that are high in fibre and low in sugar and starch – an ideal fibre base for horses and ponies as part of a balanced diet.
Do not restrict forage intake, it is important to keep the hindgut moving but talk to your vet or qualified nutritionist on how much you should feed alongside small quantities of feed.
Owners can have their forage tested and analysed for WSC (water soluble carbohydrates – sugar and fructans). It should be below 10%.
Soaking hay for 12 – 16 hours can reduce the WSC by up to 50%.
If your horse or pony is recovering from Cushing’s Disease and you have been advised by your vet to keep them off grass for a period, make sure you use ménages for turnout time.
Consult your vet for any veterinary advice or a qualified nutritionist contact the British Horse Feeds team for feed advice.
Read more about our feeds here.