CASE OF THE MONTH – DR. MICHAEL CUMMINGS

CAN’T HANDLE THE STRESS? : CANINE HYPOADRENOCORTICISM (ADDISON’S DISEASE)

Bianca, a 7yr old, female, spayed Yorkshire Terrier presented to our hospital because she had been low on energy and had vomited a couple of times over the weekend and was trembling at times. Her owner had told us that she had been having diarrhea occasionally over the past few weeks, but she thought that was because she was fond of

chewing twigs and leaves. But she was concerned, mainly, about her marked lack of energy. She was always very active. But over the weekend she had become increasingly weak.

ANATOMY

The adrenal glands are located near the kidneys and very close to the major blood vessels of the body. This allows the hormones that the glands produce to enter the bloodstream very rapidly. The inner portion of the cortex of the gland is responsible for producing steroid hormones that the animals require in times of stress, like cortisol. The outer portion of the cortex produces hormones, mineralocorticoids, which keep electrolytes in balance to maintain muscle strength and heart rate to name a few things.

HYPOADRENOCORTICISM

Hypoadrenocorticism is sometimes referred to as Addison’s disease, after the British physician, Thomas Addison, who first described the disease. It is a disorder of the adrenal glands. It mainly occurs in dogs, very rarely in cats. In pets that develop the disease the portions of the glands that produce the steroid and mineralocorticoid hormones no longer function. Breeds which are at an increased risk of developing this disease are West Highland White Terriers, Poodles, Great Danes, Rottweilers and Wheaton Terrier

When animals develop a severe case of this disease it is a life threatening condition called an “Addisonian crisis”, which requires emergency treatment. The animals present in a state of “shock”, unable to walk or stand. The heart rate is very low and muscles are weak.

The disease is progressive so often the symptoms go unnoticed for several weeks or months as the signs seem to come and go. The symptoms can worsen in stressful situations such as travel or boarding.

The most common symptoms are weakness, decreased appetite and vomiting. This may progress to diarrhea, weight loss, trembling and increased thirst and urination.

An initial blood screen can give indications that a pet has the condition. If it is suspected from the initial test an additional more specific test is then performed to confirm. The pet is initially hospitalized and given intravenous fluids to correct electrolyte imbalances and is also given steroid injections to avoid shock. Once stable, the confirmatory blood test is performed.

OUTCOME

Bianca was stabilized and it was confirmed that she had hypoadrenocorticism. She started treatments of replacement mineralocorticoid hormones by injection every month and steroid pills daily She gets more steroid pills if she is going to be in a stressful situation. She had to have her blood checked regularly at first to make sure the electrolyte levels are balanced and if she is receiving enough medication. She has been stable now for many months and is enjoying an active happy life again.