Overview of the Dog ACTH Stimulation Test
The ACTH stimulation test is used to measure how well the adrenal glands are working. The ACTH stimulation test is used to diagnose dog Cushing’s disease or Addison’s disease.
Cushing’s disease results in the excessive production and release of the cortisol, also described as "hyperadrenocorticism". Addison’s disease, or "hypoadrenocorticism", is caused when the adrenal glands produce too little cortisol.
The ACTH stimulation test involves injecting a small amount of ACTH (adrenocorticotropic hormone), and then taking a blood sample to measure cortisol levels.
ACTH Stimulation Test For Monitoring Dog Cushing's Disease
An ACTH stimulation test is a blood test for Cushing's disease, or hyperadrenocorticism. It can be used to diagnose Cushing's, although another blood test (the low-dose dexamethasone suppression test) is preferred for diagnosis in most cases. The ACTH stim test can have false positive and false negative results, so should always be interpreted carefully.
The ACTH stimulation test is most useful to monitor dogs who are being treated for Cushing's disease with trilostane (Vetoryl). In order to make sure the dog is on an appropriate dose to regulate their adrenal activity, an ACTH stimulation test should be measured on a regular basis. This helps your veterinarian to adjust the dose as needed. If this testing is not done regularly, your dog could be at risk of dangerous side effects.
The ACTH stimulation test is noninvasive. Your dog will stay in the hospital for a short amount of time. An initial blood sample is collected and then an injection of cortrosyn, an adrenal stimulating substance, is given. A second blood test is performed an hour later. The test compares cortisol levels before and after stimulation. The test is very safe but may be expensive due to the cost of the cortrosyn injection.
ACTH Stimulation Test For Diagnosing Dog Addison's Disease
History, physical, blood chemistry and electrolyte panel point strongly towards the diagnosis of Addison's disease, but in order to confirm it we have to test the adrenal gland itself, and the most reliable way to do so is ACTH stimulation test.
An ACTH stimulation test is the definitive test for Addison's disease. Addison's disease, or hypoadrenocorticism, occurs when the adrenal glands are not functioning appropriately. The adrenal gland produce mineralcorticoids which affect electrolyte balances, and glucocorticoids which have multiple systemic effects on the body. When they are not functioning appropriately, dogs may become very ill with a variety of symptoms. Sometimes they can present in an emergency crisis.
An ACTH stimulation test measures blood cortisol levels. An initial blood test (resting cortisol) is performed, and then an adrenal stimulating hormone called Cortrosyn is administered IV. An hour later, a second blood test is performed. If cortisol levels are low and do not rise with stimulation, a diagnosis of Addison's disease is made. This test is noninvasive, safe, and fairly quick. The results are usually easy to interpret. This test should be done for any dog in which Addison's disease is a possibility.