Cushing's disease, also known as hyperadrenocorticism, is when the adrenal glands near the kidneys produce too much of certain hormones such as cortisol. The adrenal glands normally produce hormones that regulate many body functions, but sometimes they malfunction. The most common signs are increased urination with increased water consumption (a condition called polyuria/polydypsia or PU/PD, which you may hear your veterinarian mention), an increased in appetite, and a decrease in activity level. Poor hair coat and a pot-bellied appearance are also common. These signs are not definitive of Cushing's however, and the veterinarian may do other tests to rule out other conditions such as diabetes or hypothyroidism.
If your veterinarian is suspicious of Cushing's disease, he or she will perform a test called a low dose dexamethasone suppression test (LDDS). A blood sample will be taken in the morning as a baseline of the cortisol that is already being produced by the adrenal glands. Your dog will then be injected with dexamethasone, which will lower the amount of ACTH produced by the pituary gland at the base of the brain, which in turn lowers the amount of cortisol produced by the adrenal glands. Blood samples will be taken four hours after the dexamethasone injection and again eight hours after the dexamethasone injection. In patients with Cushing's disease, the amount of cortisol released will remain very high.
Treatment for Cushing's disease depends on which type of Cushing's disease your pet has. By and large, the most common form of Cushing's disease is pituary-induced. This is when a tumor of the pituary gland (located at the base of the brain) causes the gland to overproduce ACTH which in turn stimulates the adrenal glands to produce cortisol. These tumors can vary in size and be either malignant or benign. In dogs with this form of Cushing's disease (which accounts for approximately 85% to 90% of cases seen), proper medical care and medication can allow them to live long and normal lives.
Less commonly Cushing's disease can be the result of a benign or malignant tumor of the adrenal gland. Surgical removal of benign tumors can be curative. In the case of malignant tumors, surgery may help for a period of time but the overall prognosis is much less favorable.
Cushing's disease may also iatrogenic, which is caused by medical treatment. In the case of iatrogenic Cushing's disease, excessive administration of oral or injectable steroids (commonly given for allergies or suppression of immune-mediated disease) are to blame. Never discontinue steroids without talking to your veterinarian. Such drugs can cause the adrenal glands to produce less hormone and a tapering dose is needed to ensure that the adrenal glands can have time to resume their normal function.
Your dog will be medicated with Vetoryl, which is an adrenocortisol suppressant. In order to properly work, the veterinarian will need to monitor how the Vetoryl affects the cortisol levels so they do not remain too high or become too low. 14 days after starting Vetoryl the veterinarian will need to do an ACTH stimulation test. ACTH is a hormone that stimulates the adrenal glands to produce cortisol and adrenaline. Your dog will have a blood sample drawn and then injected with a synthetic portion of ACTH. This should trigger the adrenal glands to produce cortisol. After an hour another blood sample will be taken to compare ACTH levels. If the ACTH levels are still too high, the dosage of Vetoryl will need to be increased and another ACTH stimulation test will need to be performed 14 days after the dosage increase. Once levels are within normal limits, another ACTH stimulation test will need to be performed in one month. If levels remain within normal limits, tests will need to be done every 3 - 6 months to monitor levels. It is necessary to perform these tests to minimize the risk of harmful side-effects or complications that could be dangerous to your dog.
If your veterinarian is suspicious of Cushing's disease, he or she will perform a test called a low dose dexamethasone suppression test (LDDS). A blood sample will be taken in the morning as a baseline of the cortisol that is already being produced by the adrenal glands. Your dog will then be injected with dexamethasone, which will lower the amount of ACTH produced by the pituary gland at the base of the brain, which in turn lowers the amount of cortisol produced by the adrenal glands. Blood samples will be taken four hours after the dexamethasone injection and again eight hours after the dexamethasone injection. In patients with Cushing's disease, the amount of cortisol released will remain very high.
Treatment for Cushing's disease depends on which type of Cushing's disease your pet has. By and large, the most common form of Cushing's disease is pituary-induced. This is when a tumor of the pituary gland (located at the base of the brain) causes the gland to overproduce ACTH which in turn stimulates the adrenal glands to produce cortisol. These tumors can vary in size and be either malignant or benign. In dogs with this form of Cushing's disease (which accounts for approximately 85% to 90% of cases seen), proper medical care and medication can allow them to live long and normal lives.
Less commonly Cushing's disease can be the result of a benign or malignant tumor of the adrenal gland. Surgical removal of benign tumors can be curative. In the case of malignant tumors, surgery may help for a period of time but the overall prognosis is much less favorable.
Cushing's disease may also iatrogenic, which is caused by medical treatment. In the case of iatrogenic Cushing's disease, excessive administration of oral or injectable steroids (commonly given for allergies or suppression of immune-mediated disease) are to blame. Never discontinue steroids without talking to your veterinarian. Such drugs can cause the adrenal glands to produce less hormone and a tapering dose is needed to ensure that the adrenal glands can have time to resume their normal function.
Your dog will be medicated with Vetoryl, which is an adrenocortisol suppressant. In order to properly work, the veterinarian will need to monitor how the Vetoryl affects the cortisol levels so they do not remain too high or become too low. 14 days after starting Vetoryl the veterinarian will need to do an ACTH stimulation test. ACTH is a hormone that stimulates the adrenal glands to produce cortisol and adrenaline. Your dog will have a blood sample drawn and then injected with a synthetic portion of ACTH. This should trigger the adrenal glands to produce cortisol. After an hour another blood sample will be taken to compare ACTH levels. If the ACTH levels are still too high, the dosage of Vetoryl will need to be increased and another ACTH stimulation test will need to be performed 14 days after the dosage increase. Once levels are within normal limits, another ACTH stimulation test will need to be performed in one month. If levels remain within normal limits, tests will need to be done every 3 - 6 months to monitor levels. It is necessary to perform these tests to minimize the risk of harmful side-effects or complications that could be dangerous to your dog.
