Learning more about the procedure and cost of ACTH test for dogs is something of interest to dog owners with dogs suspected of suffering from a medical condition known as Addison's disease. This disease was first described by Thomas Addison, a graduate of the University of Edinburgh Medical School in 1855. Addison disease is known for causing vague symptoms that may wax and wane over a period of time making diagnosis quite a challenge. Ruling out this disease is important, considering that it may progress and lead to what is known as an Addisonian Crisis.
A Word About Addison Disease
Addison disease in dogs is often a condition that is underdiagnosed and often casually discovered when running other tests. In more unfortunate cases, the disease is discovered only once the dog develops a life-threatening Addisonian Crisis. Symptoms often become more evident following a stressful situation (boarding in a kennel, traveling, new pet, recent move).
Addison disease in dogs occurs when the dog's adrenal glands fail to work as they should. In most cases, this dysfunction occurs as result of an immune-mediated destruction of adrenal tissue. In other words, the immune system goes topsy-turvy and starts destroying things it shouldn't destroy.
When the adrenal glands fail, a shortage in the production of glucocorticoids such as cortisol or mineralocorticoids such as aldosterone occurs as a result. This leads to a significant imbalance of the dog's levels of potassium, sodium and water in the body.
Female dogs are more often affected than male dogs and the disease has a tendency to present in middle-aged dogs, generally between the ages of 4 to 7 years old, although this condition can and does occur in dogs of any age or gender.
Treatment for Addison disease depends on whether the affected dogs has a mineralocorticoid deficiency, a glucocorticoid deficiency, or both. Depending on the vet's findings, a medication known as fludrocortisone (Florinef) or monthly injections of desoxycorticosterone pivlate (DOCP) are prescribed. Some dogs will require prednisone.
Did you know? The ACTH test is also useful for diagnosing dogs with Cushing's Disease, which is the total opposite problem where dogs develop an overproduction of cortisol.
The ACTH Test for Dogs
While in dogs suffering from Addison disease, routine blood tests (complete blood count and biochemistry profile) and urinalysis may reveal several abnormalities such as a low red blood cell count, increased lymphocytes, eosinophilia, electrolyte abnormalities such as high potassium levels and low sodium levels, low glucose levels, high calcium levels and an elevation in blood urea nitrogen (BUN) and serum creatinine levels, the gold standard test for Addison disease in dogs is ultimately the ACTH test.
The ACTH tests also comes handy for monitoring dogs with Cushing's disease taking the medications trilostane (Vetoryl) or mitotane (Lysodren).
In particular, in dogs given trilostane, it is extremely important that this medication is given in the morning with food and then have the ACTH test done 3 to 4 hours later. Fasting in these dogs must be avoided considering that fasting would invalidate the ACTH test, warns veterinarian Dr. Mark E. Peterson.
Procedure of ACTH Test for Dogs
Prior to the test, the dog undergoing testing should discontinue any steroid or adrenal extract supplements considering that these may impact the test results.
According to Dr. Peterson, for dogs on prednisone that are doing well, the prednisone should be stopped for at least 24 hours (48 hours is better) before the recheck exam and ACTH stimulation test. Consult with your vet for specific guidelines.
The purpose of the ACTH test in dogs is assessing the correct functioning of the dog's adrenal glands. During the test, a blood sample is collected so to attain a baseline for cortisol levels. Afterward, the dog is injected (by IV preferably, or intramuscular injection) with a small amount of synthetic ACTH (adrenocorticotropic hormone). After that, the amount of cortisol produced by the dog's adrenals glands is measured by taking another blood sample.
The whole testing time may vary between 1 hour for the shorter tests up to 24-48 hours for the longer tests. Generally, the cortisol levels of healthy dogs will double compared to the baseline number. In dogs suffering from Addison disease instead, they will have very low basal cortisol levels, and once the ACTH is administered, the levels will not rise as much.
In dogs suffering from early adrenal dysfunction, pre-and post-ACTH cortisol concentrations may not be suggestive of the disease, but in such cases, it's helpful to test again in four to eight weeks for signs of progression.
"The results on a normal patient will be 1-4 on the pre sample and 5-20 on the post sample. A dog with Cushing's disease will usually be high on the pre and greater than 25 on the post with a gray zone between 20 and 25 on the post. A dog with Addison's disease will be low on the pre and have no appreciable change on the post. "~Dr. Bruce Coston
Cost of ACTH Test for Dogs
The cost of ACTH test for dogs will obviously vary from one location and another. Generally, veterinary costs tend to be higher in urban areas. Your best bet for accuracy, is to call around several vet clinics and see if their receptionists are willing to give out some rough estimates.
On top of location, the cost of ACTH for dogs tends to also vary based on the dog's weight. The heavier the dog, the more expensive the test considering that the amount of the ACTH gel used for larger dogs will be more.
Generally, you may expect to pay about $60 for each blood test, and then around $20 to $40 for the actual injection of ACTH.
For a small dog the cost of ACTH test for dogs may therefore range anywhere from $140 to $160, explains veterinarian Dr. Rebecca. However, large dogs may cost anywhere between $200 and $500.
If the procedure takes several hours, you may have to pay the additional price for keeping your dog in one of the hospital's runs and having personnel monitor and take care of your dog.
- DVM360: Managing atypical and critical cases of primary hypoadrenocorticism in dogs
- Insights into Veterinary Endocrinology by Dr. Mark Peterson