Addison’s Disease, also known as hypoadrenocorticism, involves the malfunction of the adrenal glands, which are located adjacent to the kidneys. This results in an inability to produce corticosteroids and this can dramatically affect an animal’s health if it goes untreated, but management with medications can result in a good quality of life.
The average Addison’s Disease patient is a young female dog, about four years of age. The disease can occur in other species, including cats, but it’s relatively uncommon.
How the Disease Works
The adrenal glands manufacture hormones, which have an effect on a vast array of body systems in a variety of ways. In Addisonian pets, the outer part of the glands, called the cortex, fails to produce corticosteroids, which are a type of hormone that enables the body to properly handle stress.
When the adrenal glands are working properly, the glands dispatch hormones called corticosteroids. One type of corticosteroid is the glucocorticoid, which has an effect on sugar, protein and fat metabolism. The glucocorticoids, which include cortisol, also shift the metabolism into a mode where the body is enabled to actively expend fuel reserves, initiating a “flight or flight” response. Another form of corticosteroid, mineralocorticoids, control electrolytes like sodium and potassium. In a pet with Addison’s Disease, all of these functions are impaired, so the body cannot properly handle stress, therefore, the slightest bit of stress results in malfunctions in an array of body systems, and this can send the body into a state of shock which can ultimately lead to death.
Symptoms of Addison’s Disease
“Most Addisonian dogs are diagnosed after they come into the vet’s office suffering from Addisonian shock and this results from the hormonal imbalance. This can be a very difficult disease to diagnose, particularly when a vet is not familiar with this disease – the symptoms are often suggestive of many other illnesses, but more comprehensive diagnostic testing, often performed by a specialist, usually leads to diagnosis,” explained Dr. Michael Levine, DVM.
Symptoms can be dramatic and varied from patient to patient. They include:
- Lethargy
- Vomiting
- Regurgitation of undigested food shortly after eating
- Diarrhea
- Low Blood Sugar
- Slowed Heart Rate
- Seizure and Tremors
- Collapse
- Shock
Diagnosis of Addison’s Disease
The diagnosis for Addison’s Disease is very specific: the ACTH Stimulation Test. This test takes between 24 to 36 hours to complete. The patient is given a hormone called ACTH, which triggers the release of corticosteroids in a time of stress. This will cause elevated cortisol levels in a normal pet, but a pet with Addison’s Disease is not manufacturing cortisol, therefore, there will be no response to the ACTH. This lack of a response is suggestive of Addison’s Disease.
Treatment for Addison’s Disease
There is no cure for Addison’s Disease, but the condition can effectively be managed with medication. There are two approaches to treating Addison’s Disease; both approaches entail replacing the missing hormones. The first approach involves a drug called Florinef, which serves to replace the mineralocorticoids and the glucocorticoids, therefore keeping the electrolytes and metabolism in balance. This drug is typically given in pill form twice daily.
The second approach involves the use of two separate drugs, one to serve as a replacement for the mineralocorticoids, and the other to replace the glucocorticoids. Once every 25 to 28 days (on average), an intramuscular injection of a drug called DOCP - with the brand name“Percorten-V” - is administered and this serves to replace the mineralocorticoids, therefore keeping the electrolytes at an appropriate level. Daily doses of a steroid drug like prednisone serve to replace the glucocorticoids.
Testing is required, particularly in the early phases of Addison’s Disease, to test electrolyte balance and the medication dosage and frequently is adjusted accordingly. But once the patient is stable, electrolyte testing is typically performed once every six months. Extra care must be taken during times of stress, as this places added strain on the impaired system of an Addisonian animal. During a stressful event or period, like a stay at a kennel, extra prednisone is often provided to help the body better handle the stressful experience on a physiological level.
