Steroid hormones, specifically the class known as glucocorticosteroids produced by the adrenal glands, serve over 50 vital functions within the body. Some of the more important ones have to deal with carbohydrate, protein, and fat utilization and with maintaining water and electrolyte balance within the body. Veterinarians fighting allergic reactions or inflammation in dogs and cats rely on glucocorticosteroids for their anti-inflammatory effects when given at low dosages. Similarly, since high doses of glucocorticosteroids can suppress the immune system, they are quite useful in treatment against autoimmune diseases in pets, including pemphigus, a disease that causes severe skin lesions in affected dogs.
Unfortunately, since steroid hormones help maintain a delicate balance within the body, an overproduction of these hormones within the body can upset this balance. This is precisely what happens in Cushing’s disease. An overproduction of glucocorticosteroids from the adrenal glands occurs within the body, usually as the result of a tumor affecting one or both glands, or, more commonly, a tumor affecting the pituitary gland. The disease is most common in dogs over 8 years of age. Furthermore, poodles, boxers, and dachshunds seem to be afflicted with a greater frequency than other breeds. Fortunately, the condition is rarely seen in cats.
Some of the clinical signs seen in dogs with Cushing’s disease include a marked increase in water and food consumption, an increase in elimination activity, lethargy and exercise intolerance, and a generalized reduction in muscle size and tone, which, when it affects the muscles of the abdominal wall, leads to a characteristic pot-bellied appearance.
The skin and coat changes that occur in a dog with Cushing’s disease might be the first clues as to the existence of the problem. A generalized thinning of the haircoat and skin will be seen, with flakiness, pigmentation, and secondary infections. Eye problems are common in these dogs, too, with recurring ulcers affecting the cornea. Because high levels of steroids have a suppressing influence on the immune system, secondary infections, especially bladder infections, are often seen in these dogs as well. Finally, if a tumor is present in the pituitary gland at the base of the brain, neurological problems might occur as pressure is increased on the brain.
These signs can lead a clinician to suspect Cushing’s disease, but more extensive blood testing and radiographic X rays are usually required to confirm a diagnosis. Measuring actual blood levels of steroids within the bloodstream is one way to test for Cushing’s disease; other methods include injecting small amounts of special synthetic hormones, designed to alter the production of steroids within the body, into the dog and measuring the body’s response to them. If these hormones cannot alter the steroid production, then a diagnosis can be made.
Once a dog is diagnosed with Cushing’s disease, therapy may be instituted in a number of ways. Surgical removal of the tumor in either the adrenal glands and/or pituitary gland can be attempted, but this is a very difficult procedure associated with many postoperative complications.
Chemotherapy can be employed to target the adrenal glands and reduce the amount of steroids being produced by them. Used correctly, this treatment can reduce or eliminate the clinical signs seen and greatly improve a dog’s quality of life. Close veterinary monitoring for the appearance of side effects during the initial treatment stage is recommended. Therapy is usually required for life.
Because of the intense management required with these modes of therapy, some pet owners prefer to stick to conservative treatment when dealing with this disease in their dogs. In these cases, dogs should be placed on high-protein diets to counteract protein loss caused by the disease. In addition, treating secondary problems as they arise—such as skin infections, bladder infections, and corneal ulceration is necessary. Because the tumors responsible for Cushing’s disease are usually slow-growing, most dogs can live for up to 2 years with this treatment approach alone.
Unfortunately, since steroid hormones help maintain a delicate balance within the body, an overproduction of these hormones within the body can upset this balance. This is precisely what happens in Cushing’s disease. An overproduction of glucocorticosteroids from the adrenal glands occurs within the body, usually as the result of a tumor affecting one or both glands, or, more commonly, a tumor affecting the pituitary gland. The disease is most common in dogs over 8 years of age. Furthermore, poodles, boxers, and dachshunds seem to be afflicted with a greater frequency than other breeds. Fortunately, the condition is rarely seen in cats.
Some of the clinical signs seen in dogs with Cushing’s disease include a marked increase in water and food consumption, an increase in elimination activity, lethargy and exercise intolerance, and a generalized reduction in muscle size and tone, which, when it affects the muscles of the abdominal wall, leads to a characteristic pot-bellied appearance.
The skin and coat changes that occur in a dog with Cushing’s disease might be the first clues as to the existence of the problem. A generalized thinning of the haircoat and skin will be seen, with flakiness, pigmentation, and secondary infections. Eye problems are common in these dogs, too, with recurring ulcers affecting the cornea. Because high levels of steroids have a suppressing influence on the immune system, secondary infections, especially bladder infections, are often seen in these dogs as well. Finally, if a tumor is present in the pituitary gland at the base of the brain, neurological problems might occur as pressure is increased on the brain.
These signs can lead a clinician to suspect Cushing’s disease, but more extensive blood testing and radiographic X rays are usually required to confirm a diagnosis. Measuring actual blood levels of steroids within the bloodstream is one way to test for Cushing’s disease; other methods include injecting small amounts of special synthetic hormones, designed to alter the production of steroids within the body, into the dog and measuring the body’s response to them. If these hormones cannot alter the steroid production, then a diagnosis can be made.
Once a dog is diagnosed with Cushing’s disease, therapy may be instituted in a number of ways. Surgical removal of the tumor in either the adrenal glands and/or pituitary gland can be attempted, but this is a very difficult procedure associated with many postoperative complications.
Chemotherapy can be employed to target the adrenal glands and reduce the amount of steroids being produced by them. Used correctly, this treatment can reduce or eliminate the clinical signs seen and greatly improve a dog’s quality of life. Close veterinary monitoring for the appearance of side effects during the initial treatment stage is recommended. Therapy is usually required for life.
Because of the intense management required with these modes of therapy, some pet owners prefer to stick to conservative treatment when dealing with this disease in their dogs. In these cases, dogs should be placed on high-protein diets to counteract protein loss caused by the disease. In addition, treating secondary problems as they arise—such as skin infections, bladder infections, and corneal ulceration is necessary. Because the tumors responsible for Cushing’s disease are usually slow-growing, most dogs can live for up to 2 years with this treatment approach alone.
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