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Visible Effects
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Horses with Cushing̵7;s, also called hyperadrenocorticism, keep a heavy winter coat of hair all year, not shedding it in the warm months like healthy animals. The hair appears coarse and wavy and is especially long on the horse̵7;s belly, fetlocks and under the jaw.
Equine patients exhibit a loss of muscle over their topline, meaning they appear thinner down their backs along the spine, over the haunches and along the back of the neck. Older horses, in particular, can develop a swayback and look like they have a pot belly. They may lose weight even though they are eating normally.
Physical Effects
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Because the high levels of corticosteroids adversely affect the immune system, horses with Cushing̵7;s may develop a series of infections. Diseases of the skin and mouth, hoof abscesses, an overgrowth of intestinal parasites and respiratory infections are common. Wounds may be slow to heal.
Some horses may contract laminitis, an inflammation of the lamina (lining) of the hoof. When the lamina becomes diseased, the animal̵7;s coffin bone (the bone directly above the bottom of the hoof) will begin to turn inward and can push its way through the hoof bottom. Laminitis is painful, progressive and difficult to treat and, in some horses, incurable. These animals will need to be euthanized.
Mares with Cushing̵7;s can experience abnormal estrous--either longer than the normal five to seven days or completely absent. Some non-pregnant mares may let down colostrum (milk) into their udders.
Sometimes excessive growth of the pituitary tumor exerts pressure on the hypothalamus and surrounding brain tissue. When that occurs, the horse̵7;s head may tilt and he can develop blindness and dementia.
Behavioral Effects
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Healthy horses typically drink between six and ten gallons of water daily. Animals with Cushing̵7;s can consume abnormal amounts of water, drinking more than 20 gallons in a day. Consequently, they will experience a drastic increase in urination.
Cushing̵7;s horses usually show a noticeable weight loss but may also have an increased appetite. The weight loss and muscle atrophy often pave the way for a severe lack of energy and lethargy.
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Equine Cushing's Disease Effects
If your older horse doesn̵7;t shed out his fluffy winter coat in the spring like he normally would, he may have developed equine Cushing̵7;s disease. A small benign tumor or growth in your horse̵7;s pituitary gland (an endocrine gland located at the base of his brain) has stimulated an overproduction of hormones and steroids, causing the disease. According to the American Association of Equine Practitioners, the clinical signs and effects of Cushing̵7;s ̶0;can vary depending upon the stage of the disease.̶1;