Cushing's disease, also known as hyperadrenocorticism, is a common hormone disease of older dogs. It occurs when the adrenal glands secrete an excessive amount of glucocorticoid hormones. Glucocorticoid hormones exert a great influence on other hormones and can affect every organ of the body. Most frequently, up to 80 percent of the time, the disease is caused by a slow-growing tumor on the pituitary gland. The other 20 percent of the time, it is caused by a tumor on the adrenal glands.
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Symptoms of Cushing's Disease
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Cushing's disease involves subtle symptoms you may not notice until your dog is quite ill. Classic symptoms such as increased thirst and urination may be explained away, and the swollen belly appearance may seem only the result of increased appetite, which is also a feature of the disease. Increased panting or reduced activity may simply seem like the slowing down of an aging dog, as may weakness in the back legs. Skin problems may develop, such as thinning skin, unusual skin lumps, pigmentation changes or unexplained hair loss. Because the symptoms are so vague and can be explained by other factors, many dogs may have the disease for as many as six years before being correctly diagnosed.
Progression of Symptoms
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Because of the increased water consumption, dogs may have accidents inside the house. Urinary infections are common with Cushing's. Increased appetite may cause an increased need to defecate. Skin problems can cause irritation, prompting the dog to lick at areas on the feet. This licking can eventually cause granulomas--open sores on the skin and feet, which may result in localized bacterial infections. The dog may show increased weakness as the heart muscle is affected.
Diagnosis and Treatment
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Cushing's disease is diagnosed through urine, blood and saliva tests. Ultrasound may be used to detect the location of tumors. Treatment involves a number of therapies, including surgery to remove the adrenal tumor that causes the excess production of cortisol. Surgery is not currently recommended for pituitary tumors. Medication is the most common treatment for Cushing's disease. Vetoryl, Anipryl and Lysodren are all used to inhibit cortisol production, but treatment must be monitored carefully, because side effects can be serious and life threatening. Liver and kidney problems, lack of energy, vomiting, diarrhea and weight loss are potential side effects.
Progression of Treated Cushing's Disease
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Many dogs can have quality years ahead of them with proper Cushing's disease treatment. However, this depends wholly on the willingness of owners to give the animals the daily medications they need to help inhibit the cortisol production. Owners also need to consistently bring their dogs to the veterinarian's office for periodic blood tests.
Progression of Untreated Cushing's Disease
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Left untreated, dogs with Cushing's disease can develop diabetes, liver and kidney failure, congestive heart disease and chronic infections of the eyes, ears, skin, gums and bladder. Cushing's disease may shorten a dog's life by many years.
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