The most common adrenal gland problems in dogs produce surprisingly different signs depending on whether the glands are overproducing or underproducing hormones. Cushing’s disease (too much cortisol) causes increased thirst, a pot belly, and hair loss. Addison’s disease (too little cortisol) causes vomiting, lethargy, and mysterious episodes of illness that come and go. A third, rarer problem, adrenal tumors that pump out adrenaline, can trigger sudden collapse and heavy panting. Here’s how to recognize each one.
How Adrenal Glands Work in Dogs
Your dog has two small adrenal glands sitting just in front of the kidneys. They produce cortisol, which regulates metabolism, blood sugar, and the stress response. They also produce aldosterone, a hormone that controls the balance of sodium and potassium in the blood, which in turn affects hydration, blood pressure, and heart rhythm. When these glands malfunction in either direction, the effects ripple across nearly every system in the body.
Signs of Cushing’s Disease (Too Much Cortisol)
Cushing’s disease, or hyperadrenocorticism, is the most common adrenal problem in dogs. It typically shows up in dogs around age nine or older and develops gradually, so many owners initially write off the changes as normal aging. The hallmark signs are hard to miss once you know what to look for:
- Excessive thirst and urination. Dogs may drain their water bowl repeatedly and need to go outside far more often, including overnight.
- Increased appetite. Some dogs become ravenous, begging constantly or getting into food they’d normally ignore.
- Pot-bellied appearance. The abdomen enlarges and sags, giving the dog a distinctly rounded belly even if they haven’t gained much weight overall.
- Hair loss. Thinning often starts over pressure points and the trunk, typically in a symmetrical pattern on both sides of the body. It can also appear as general thinning or patchy bald spots along the torso.
- Thin, fragile skin. Excess cortisol breaks down the structural protein in skin, making it paper-thin. On the belly, the skin can become so transparent that blood vessels are visible underneath. It bruises easily.
- Excessive panting and reduced activity. Dogs may pant even at rest and seem less interested in walks or play.
- Recurrent skin infections. Cortisol suppresses the immune system, so bacterial skin infections may keep returning despite treatment.
In some dogs, Cushing’s also causes hard, gritty calcium deposits in the skin, a condition called calcinosis cutis. These plaques usually develop along the back or in the groin area. They can ulcerate and form crusty sores that don’t heal well.
Signs of Addison’s Disease (Too Little Cortisol)
Addison’s disease, or hypoadrenocorticism, is often called “the great pretender” because its signs mimic so many other conditions. The pattern that sets it apart is the waxing and waning nature of the illness. Roughly 25% to 43% of affected dogs have symptoms that flare up, improve on their own, then return days or weeks later. This on-again, off-again cycle can make diagnosis frustratingly slow.
The signs owners most commonly report are poor appetite or complete refusal to eat (seen in 88% to 95% of cases), lethargy or depression (85% to 95%), and vomiting (68% to 75%). Beyond those, veterinarians frequently find thin body condition (82%), weakness (66% to 69%), and dehydration (42%). Less common but still notable signs include bloody stool, abdominal pain, and weight loss.
About one in three dogs with Addison’s has an “atypical” form where only cortisol production drops while aldosterone remains relatively normal. These dogs show the same vague signs (lethargy, vomiting, diarrhea, poor appetite) but their bloodwork doesn’t show the classic electrolyte shifts that often tip off a veterinarian. Some atypical cases are discovered incidentally during routine blood screening when albumin and cholesterol come back unusually low, with no obvious symptoms at all.
The Addisonian Crisis: Emergency Signs
Addison’s disease can simmer quietly for weeks or months, then suddenly escalate into a life-threatening emergency called an Addisonian crisis. This happens when cortisol and aldosterone drop so low that the body can no longer maintain blood pressure and heart rhythm. Dogs in crisis typically show severe depression, profound weakness, inability to stand, dehydration, and low body temperature. Collapse is significantly more common in critically ill dogs.
One counterintuitive detail: dogs in an Addisonian crisis don’t always have a fast heart rate the way you’d expect in shock. About 21% of critically ill Addisonian dogs actually present with an abnormally slow heart rate (below 70 beats per minute), caused by dangerously high potassium levels disrupting the heart’s electrical system. If your dog has been intermittently unwell and then suddenly becomes weak, cold, or unresponsive, this is a veterinary emergency.
Signs of Adrenal Tumors (Pheochromocytoma)
A less common but serious adrenal problem is pheochromocytoma, a tumor of the inner part of the adrenal gland that overproduces adrenaline-type hormones. These tumors occur mostly in older dogs. Because adrenaline surges are unpredictable, symptoms tend to be episodic. A dog may seem fine for days, then suddenly become weak, collapse, or pant heavily.
Common signs include episodic collapse, weakness, lethargy, loss of appetite, rapid breathing, racing heart rate, vomiting, and diarrhea. High blood pressure is a major concern and can occasionally cause sudden bleeding events. Some dogs also develop increased thirst and urination or fluid buildup in the abdomen. The episodic nature of these signs, particularly sudden collapse in an otherwise healthy older dog, is what distinguishes pheochromocytoma from other adrenal problems.
Which Breeds Are More at Risk
Cushing’s disease is more common in certain smaller breeds, including Poodles, Dachshunds, and terrier breeds, though it can occur in any dog. Addison’s disease has strong breed associations as well. Standard Poodles, Portuguese Water Dogs, Bearded Collies, Great Danes, and West Highland White Terriers are among the breeds with higher rates. In some of these breeds, the condition has a genetic component, so knowing your dog’s breed background can help your vet consider adrenal problems earlier in the diagnostic process.
How Adrenal Problems Are Diagnosed
Because adrenal disease signs overlap with so many other conditions, diagnosis usually requires specific hormone testing beyond routine bloodwork. The most important test is the ACTH stimulation test, which measures how your dog’s adrenal glands respond to a synthetic hormone that normally triggers cortisol release.
For Addison’s disease, a simple baseline cortisol reading can be a useful first step. If resting cortisol comes back above a certain threshold, Addison’s can be ruled out with near-100% confidence. If it’s low, the ACTH stimulation test confirms the diagnosis by showing that the adrenal glands can’t produce an adequate cortisol response even when stimulated.
Abdominal ultrasound is another valuable tool. It can detect enlarged adrenal glands with about 96% accuracy in dogs with Cushing’s disease. Normal adrenal gland thickness varies by body size, ranging from about 5 mm in small dogs to around 7 to 9 mm in larger dogs. Glands larger than these thresholds, or glands that appear asymmetric or contain visible masses, raise suspicion for tumors.
Cushing’s vs. Addison’s at a Glance
The easiest way to keep these two conditions straight is to remember they’re opposites. Cushing’s dogs eat and drink too much, gain belly weight, and lose hair. Addison’s dogs lose their appetite, lose weight, and seem intermittently sick for no clear reason. Cushing’s develops slowly over months and rarely causes emergencies on its own. Addison’s can look mild for weeks and then become a sudden crisis. Both conditions are manageable with ongoing treatment once diagnosed, but catching the signs early, especially the waxing-and-waning illness pattern of Addison’s or the classic thirst-and-belly combination of Cushing’s, is what gets your dog to a diagnosis faster.