CONDITION
Adrenocortical Carcinoma
Adrenocortical carcinoma is a cancer that arises from the outer layer of the adrenal gland — a small structure that sits near the kidney and produces hormones involved in metabolism, stress response, and fluid balance. In dogs, this type of tumour can behave in two broad ways: it may produce excessive amounts of hormones (most often cortisol, leading to signs similar to Cushing's syndrome), or it may grow without obvious hormonal activity, in which case signs relate to the mass itself or to spread elsewhere in the body. Owners often arrive at this page after imaging has identified a mass on or near the adrenal gland, or because their dog has been investigated for persistent weight gain, increased thirst, muscle weakness, or a swollen abdomen. Some dogs show no outward signs at all, and the finding is incidental during imaging for another reason. The behaviour of these tumours varies: some remain slow-growing and localised for months or years, while others invade nearby structures or spread to the liver, lungs, or lymph nodes relatively early. This page explores the signals that may suggest adrenocortical carcinoma, what is happening at a tissue and hormonal level, how the condition is investigated through imaging and laboratory tests, and the range of approaches that exist — from surgical removal to medical management of hormone excess or monitoring in cases where intervention carries significant risk.
Why this matters now
Adrenocortical carcinoma tends to appear in middle-aged to older dogs, most commonly between eight and eleven years of age, though younger animals can occasionally be affected. Certain breeds — including Poodles, Dachshunds, Labrador Retrievers, and German Shepherd Dogs — appear in clinical reports more frequently, but the tumour can arise in any breed or crossbreed. There is no clear environmental or dietary trigger; the condition appears to develop as a consequence of spontaneous changes in the cells of the adrenal cortex over time.
The course of adrenocortical carcinoma varies considerably between individuals. Some tumours remain relatively contained within the adrenal gland for months or even years, growing slowly and causing few outward changes, particularly if they do not produce excess hormone. Others invade the large blood vessels adjacent to the adrenal gland — most notably the vena cava — or spread to the liver, lungs, or abdominal lymph nodes within weeks to months of onset. Hormone-secreting tumours may produce signs that progress gradually, with metabolic changes accumulating over months, while non-functional tumours may only become apparent when the mass itself causes discomfort or when metastatic spread is detected.
Signals & patterns
Early signals
Increased thirst and urination
A dog may begin drinking noticeably more water and asking to go outside more often, or having accidents indoors despite previously reliable house-training. This pattern often develops gradually and can be attributed to excess cortisol affecting the kidneys' ability to concentrate urine.
Increased appetite with weight gain
The dog may seem persistently hungry, seeking food more actively or scavenging in ways that were not typical before. Weight may increase, particularly around the abdomen, even without a change in the amount fed.
Thinning coat or poor regrowth
The hair coat may become thinner, patchy, or slow to regrow after clipping or a seasonal shed. The skin itself may appear thinner or more fragile, and small blood vessels may become visible beneath the surface.
Reduced stamina or muscle weakness
An owner may notice the dog tires more easily on walks, has difficulty jumping onto furniture or into the car, or appears less steady on the back legs. Muscle mass may visibly decrease, particularly over the spine and hindquarters.
Abdominal enlargement
The belly may appear rounder or more pendulous, sometimes described as pot-bellied. This can result from fat redistribution, liver enlargement, or weakening of the abdominal muscles, and may develop over weeks to months.
Later signals
Persistent panting or restlessness
The dog may pant heavily even at rest or during cool weather, and may appear unable to settle comfortably. This can reflect both metabolic changes and discomfort from an enlarging mass or metastatic disease.
Visible abdominal mass or asymmetry
In some cases, a firm swelling may become palpable or visible on one side of the abdomen, particularly in lean dogs. This may indicate a large primary tumour or enlargement of the liver due to metastatic spread.
Collapse or sudden weakness
Acute episodes of weakness, collapse, or pale gums can occur if the tumour invades a major blood vessel and causes bleeding into the abdomen, or if a blood clot forms and dislodges. These episodes may be brief or prolonged.
Coughing or laboured breathing
Respiratory signs may develop if the tumour has spread to the lungs. The dog may cough intermittently, breathe more rapidly, or show reduced tolerance for exercise.
Click to read about the biological mechanisms
How this is usually investigated
Options & trade-offs
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