Addison’s disease and Cushing’s syndrome are two opposite hormonal disorders in dogs, affecting the adrenal glands but with very different symptoms, treatments, and risks. Adrenal gland disorders can throw even the most energetic pups off balance. Understanding how Addison’s and Cushing’s impact dogs helps ensure timely care and support for these serious conditions. The main difference is that Addison’s disease results from underproduction of adrenal hormones, while Cushing’s syndrome stems from overproduction. This guide explores both diseases, covering what to look for, how they’re diagnosed, and how they’re managed.

Key Takeaways

• Addison’s disease causes hormone deficiency that leads to fatigue, vomiting, and even life-threatening collapse if untreated.

• Cushing’s syndrome results from excess cortisol, often showing up as increased thirst, a pot belly, and hair thinning.

• The main difference lies in hormone levels, with Addison’s being too low and Cushing’s being too high.

• Accurate diagnosis depends on hormone testing, like ACTH stimulation for Addison’s and LDDS for Cushing’s.

• Treatment options vary significantly, with Addison’s needing hormone replacement and Cushing’s often managed with medication or surgery.

What Is Addison’s Disease in Dogs?

Addison’s disease, formally called hypoadrenocorticism, occurs when a dog’s adrenal glands fail to produce enough essential hormones that regulate blood pressure, metabolism, and stress response.

Causes

The most common cause is autoimmune destruction, where the immune system attacks the adrenal glands. Other triggers include sudden steroid withdrawal, infections, tumors, or physical trauma.

Symptoms of Addison’s Disease

Addison’s symptoms are often subtle at first:

• Lethargy or depression

• Vomiting and diarrhoea

• Weight loss and decreased appetite

• Trembling or shaking

• Low blood pressure, dehydration, or collapse (Addisonian crisis)

What Is Cushing’s Syndrome in Dogs?

Also known as hyperadrenocorticism, Cushing’s syndrome results from the adrenal glands producing too much cortisol—a hormone tied to stress, metabolism, and immune response.

Causes

Cushing’s is most often caused by a pituitary tumour (pituitary-dependent hyperadrenocorticism). It can also stem from an adrenal gland tumour or extended use of corticosteroids.

Symptoms of Cushing’s Disease

Cushing’s tends to develop gradually:

• Increased thirst and urination

• Bloated or pot-bellied appearance

• Thinning coat and recurring skin infections

• Increased appetite and panting

Addison’s vs. Cushing’s in Dogs: At-a-Glance Comparison

Hormone Levels

Addison’s is caused by too little adrenal hormone, especially cortisol and aldosterone. Cushing’s results from the opposite problem—too much cortisol flooding the system.

Common Cause

Autoimmune destruction is the primary cause of Addison’s in dogs. Cushing’s is most often caused by a benign pituitary tumour that overstimulates cortisol production.

Symptoms

Addison’s leads to sudden fatigue, gastrointestinal issues, and collapse during stress. Cushing’s causes gradual changes like excessive thirst, a pot belly, and hair thinning.

Diagnosis

Addison’s is diagnosed with an ACTH stimulation test that evaluates adrenal gland response. Cushing’s is confirmed with a low-dose dexamethasone suppression (LDDS) test measuring cortisol regulation.

Treatment

Treatment for Addison’s includes daily or monthly hormone replacement to maintain balance. Cushing’s may require medications like Trilostane or Mitotane, or in some cases, surgery.

Emergency Risk

An Addisonian crisis can be fatal without fast intervention using IV fluids and steroids. Cushing’s poses long-term health risks, including diabetes, infections, and organ failure.

How These Conditions Are Diagnosed

Blood Tests

Routine bloodwork can reveal valuable clues when adrenal disorders are suspected. Addison’s may show low sodium and high potassium levels, pointing to aldosterone deficiency. Elevated liver enzymes and dilute urine are more typical in dogs with Cushing’s.

ACTH Stimulation Test

The ACTH stimulation test is used to diagnose Addison’s disease by assessing the adrenal glands' hormone production. It involves administering synthetic ACTH and measuring the cortisol response. A poor response typically confirms Addison’s.

Low-Dose Dexamethasone Suppression (LDDS) Test

The LDDS test helps diagnose Cushing’s by tracking how cortisol levels change after dexamethasone is introduced. Healthy dogs suppress cortisol levels, while those with Cushing’s often do not. It is one of the most accurate tools for confirming the condition.

Imaging (Ultrasound, MRI)

Imaging such as ultrasound or MRI can help identify tumours on the adrenal or pituitary glands. These scans also aid in distinguishing between pituitary-dependent and adrenal-dependent Cushing’s. Imaging results may guide whether surgery or medical management is most appropriate.

Treatment Options for Addison’s Disease

Hormone Replacement Therapy

Long-term hormone replacement is essential for Addison’s and helps dogs maintain hormonal stability. Monthly injections like Percorten-V or daily pills such as Florinef are common treatments. A low dose of prednisone is also used to support cortisol levels.

Emergency Management

During an Addisonian crisis, dogs need immediate veterinary care to survive. Treatment involves IV fluids, steroids, and electrolyte replacement to stabilise their condition. Prompt intervention can prevent life-threatening complications.

Treatment Options for Cushing’s Syndrome

Medications

Trilostane (Vetoryl): Reduces cortisol production and is widely used in managing Cushing’s syndrome. It works by blocking cortisol synthesis in the adrenal glands. Most dogs tolerate it well, and it’s commonly prescribed for long-term treatment.

Mitotane (Lysodren): Destroys adrenal tissue and is used in more aggressive or resistant cases. This medication is more potent and can carry greater risks, requiring careful dosage control. It may be chosen when Trilostane is ineffective or not suitable.

Surgery

Adrenal gland tumours may require surgical removal, especially when the condition is adrenal-dependent. This approach offers the potential for a cure if the tumour is benign and localised. Surgery is typically performed by a specialist and may carry risks based on tumour size and location.

Monitoring

Ongoing monitoring is critical to ensure the medication remains effective and safe. ACTH stimulation tests and bloodwork help guide dosage adjustments. Routine vet visits allow for early detection of any side effects or changes in the dog’s condition.

Prognosis and Quality of Life

Living with Addison’s

Dogs diagnosed with Addison’s can live happy, healthy lives with the right long-term care. Consistent hormone therapy and regular vet visits are key to maintaining their well-being. Monitoring hormone levels ensures they stay stable and resilient during daily life and stress.

Living with Cushing’s

Cushing’s syndrome doesn’t have to limit a dog’s quality of life when managed correctly. With the right medication, monitoring, and support, many dogs adjust well and remain active. However, without treatment, the condition may lead to more serious health issues like infections, diabetes, or organ damage.

Breeds Prone to Addison’s and Cushing’s

Addison’s-Prone Breeds

Certain breeds have a genetic predisposition to developing Addison’s disease, making early awareness critical. These dogs may benefit from closer monitoring of symptoms and routine bloodwork. Recognising breed risk can support earlier diagnosis and better outcomes.

• Standard Poodles

• Portuguese Water Dogs

• West Highland White Terriers

• Bearded Collies

Cushing’s-Prone Breeds

Some breeds are more susceptible to Cushing’s syndrome, especially as they reach middle or senior age. Regular wellness exams are essential for early detection in these cases. Understanding breed tendencies helps guide proactive healthcare.

• Dachshunds

• Beagles

• Boxers

• Boston Terriers

• Poodles

Empowering Pet Parents with Knowledge

Whether raising a tough-as-nails Staffy or a gentle senior, knowing the signs of Addison’s and Cushing’s can make a world of difference. These conditions may seem overwhelming at first, but knowledge, early diagnosis, and the right treatment plan can ensure your dog lives a long, joyful life.

At Happy Staffy Co, we’re not just about toys and gear—we’re about the health and happiness of your best mate. Because being a dog parent isn’t just about fun at the park. It’s about being there when your dog needs you most.