What is Cushing’s Disease
Cushing’s Disease is caused by a problem with the pituitary gland, which is situated at the base of the horse’s brain. One function of the pituitary gland is control of the production of natural steroids by the adrenal gland. Cushing’s is caused by either an enlargement of or benign growth within part of the pituitary gland.
Horses affected by Cushing’s produce a reduced amount of dopamine, a neurotransmitter utilized within the brain. The consequence of this imbalance is an increase in cortisol, a natural steroid, and it is this which causes most of the problems associated with Cushing’s Disease.
Signs and symptoms
Cushing’s Disease is usually seen in aged horses of 15 years plus with most cases being seen in animals in their twenties or thirties. The classical sign of Cushing’s is a long, curly coat, which doesn’t shed, although many horses show now outward signs of the disease. All types of horses can be affected although ponies appear to be at the greatest risk; mares and geldings being equally affected.
Cushing’s is often not diagnosed as owners put the signs shown down to simply, ‘old age’. Even though the affected animal’s appetite remains good, he will often lose weight and appear lethargic; muscle wastage occurs especially over the rump and saddle area caused by the breakdown of proteins. As the horse’s abdominal muscles weaken, he may develop a ‘pot-bellied’ appearance. Fatty deposits commonly appear along the crest, behind the eyes and above the root of the tail.
Affected horses often sweat but this is often dismissed especially in mild weather due to the long coat the horse is carrying. Excessive drinking and urinating is common too but this is not always easy to check on especially as older horses which are no longer in ridden work often live out.
As the horse’s immune system is suppressed, recurrent infections are common and wound healing may be slow and problematic. Laminitis and associated foot abscesses occurs in around half the affected animals with no obvious cause.
Diagnosis and treatment
Diagnosis these days is via a blood test rather than through the assessment of clinical signs as was the case until relatively recently.
There is no cure for the disease, although it can be managed to improve the affected animal’s quality of life.
· Clipping will be beneficial if the horse or pony has a very thick coat and this is vital in very warm weather.
· Good dental care is important to enable the horse to make full use of his diet and to help prevent infections. · It’s important to seek advice from a professional nutritionist to make sure that the horse’s diet is specially balanced to provide maximum nutrition and weight maintenance whilst minimizing the risk of Laminitis. Regular monitoring of the horse’s weight using a weigh tape is important to allow any necessary adjustments to his diet to be made promptly.
· Regular visits from the farrier are necessary to help prevent problems with abscesses and Laminitis.
· As the horse’s immune system is suppressed by the disease, any infection should be treated promptly.
· It is very important to keep vaccinations up to date and to make sure that the horse is regularly wormed and checked for lice etc.
If management measures alone are not enough to improve the horse’s quality of life and keep him comfortable, there are treatments available but these are expensive and life-long.
Cushing’s Disease is incurable and usually develops gradually over a number of years. Prompt diagnosis and treatment may enable the horse to live comfortably for a few years, but ultimately recurrent episodes of infection or laminitis will probably deem it necessary to have the horse put to sleep.
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