Addison's disease in dogs

November 7th, 2013
cr: houndstooth, addison's disease

Laura Greaves investigates a Cushing’s disease-related condition in dogs known as Addison’s disease.

Cosimina Nesci’s beloved dog, Jessie, may be a Spoodle, but she has the constitution of an ox. Full of beans and rarely unwell, eight-year-old Jessie only visited the vet for her vaccinations.

So when Jessie began to have bouts of uncontrollable trembling, Cosimina knew something was amiss. “It started out quite minor but then increased. We just thought Jessie was a nervous, anxious dog,” says Cosimina, from the Sydney suburb of Beecroft.

“But then Jessie started to lose her appetite and declined the chance to go for her regular walk. She became limp and seemed depressed. She just wasn’t herself, so I took her straight to the vet.”

Initial tests proved inconclusive, but Cosimina says Jessie’s vet “refused to give up” and continued searching for the cause of her distressing symptoms. Finally, in 2012, plucky Jessie was diagnosed with Addison’s disease.

What is Addison’s disease?

There are two types of Addison’s disease: primary and secondary. While Cushing’s disease is caused by too much cortisol, a natural steroid produced by the adrenal glands, dogs with primary Addison’s disease don’t have enough cortisol and/or another adrenal steroid called aldosterone.

Cortisol is produced by the outer part of the adrenal glands — small, bean-shaped glands near each kidney — while aldosterone is made by the inner medulla, which is in the centre of the glands.

Dr Sarah Reay, from Perth’s Bullsbrook and Midland Veterinary Hospitals, says primary Addison’s is not completely understood, but it’s believed to be caused by a progressive, immune-mediated destruction of the adrenal glands. In layman’s terms, that means the immune system mistakenly identifies the adrenal glands as a threat and sets about putting them permanently out of action.

“Secondary Addison’s is due to the overuse of glucocorticoid (steroid) medication. This reduces the body’s need and ability to produce natural cortisol,” she explains.

“Medications used to treat dogs with Cushing’s could sometimes destroy the outer part of the adrenal glands, called the cortex, so then the animal would develop Addison’s disease.”

Spot the signs

As with Cushing’s disease, some dogs are more susceptible to Addison’s disease than others. Females are more commonly affected than males and it mainly occurs in young to middle aged animals, though cases have been reported in animals as young as a year old.

Dog breeds that are predisposed to the condition include Great Danes, Rottweilers, Portuguese Water Dogs, Poodles, Wheaten Terriers and West Highland White Terriers.

The symptoms of Addison’s disease include lethargy, weight loss, vomiting, diarrhoea, collapse, slow heart rate, weak pulse, increased thirst and urination, hair loss, infertility and personality changes.

“As with Cushing’s, symptoms of Addison’s disease can vary greatly and can come on gradually. They can also wax and wane,” Dr Reay says.

Addison’s disease is diagnosed via extensive blood tests. Dogs with the disease will often have elevated kidney enzymes, electrolyte imbalances, anaemia and dilute urine.

“We may then go on to recommend further tests to check cortisol levels. Abdominal and thoracic ultrasonography also help to confirm a diagnosis and advanced imaging like MRI and CT may be useful if available,” she says.

Addison’s disease can be difficult to diagnose because its symptoms can mimic several other illnesses. Blood tests will rule out other conditions, including Cushing’s, kidney disease and gastrointestinal disease.

“Failure to respond to supportive medical treatment can also be a clue that an animal has Addison’s,” says Dr Reay.

Treatment options

While the diagnosis of a chronic illness is never good news, the upside is that Addison’s disease is uncommon in dogs, and the prognosis for canines that do develop the condition is positive.

Cosimina admits she was “totally ignorant” about the disease prior to Jessie’s diagnosis and initially feared the worst.

“I did some research on the internet and watched some heartbreaking YouTube clips. Jessie fitted many of the symptoms,” she says, adding that her family was resigned to losing their canine companion within six months.

Indeed, Jessie’s condition got worse before it got better. “About six months after her diagnosis, Jessie suddenly went into crisis mode,” Cosimina says.

“After being hospitalised for four days and undergoing many tests, she finally got better. We cannot explain why she went into crisis.”

Treatment of Addison’s disease involves boosting the dog’s levels of cortisol and/or aldosterone with glucocorticoid or mineralocorticoid medication, or sometimes both. The most commonly used drugs are Fludrocortisone, Prednisolone and Hydrocortisone. The patient’s electrolyte levels and kidney enzymes will be monitored regularly to see if dose adjustments are needed.

“With proper treatment and monitoring, the prognosis for primary Addison’s disease is excellent,” Dr Reay explains.

Happily, Jessie the Spoodle rallied and today she’s well on track to being her healthy, happy self again.

“Jessie is on daily medication and has a blood test to check her levels every couple of months. We are still testing to get the combination levels correct,” Cosimina says.

“Though we have had stumbling blocks, Jessie is still with us. When a pet is ill it’s very sad, but when they’re healthy and their levels regulated, you would never know they have Addison’s disease.”

Is there an alternative?

Many dog owners are understandably reluctant to see their pets on lifelong medication. With the growing popularity of holistic veterinary practices and the use of canine complementary therapies such as naturopathy, is it safe to treat Addison’s disease with natural remedies?

Dr Reay advises extreme caution, as there is no scientific data supporting the efficacy of these treatments. Consulting a holistic veterinarian is advised.

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