Symptoms & Signs of Adrenal Tumors in Dogs

Source: PetWave, Updated on July 16, 2015
Adrenal Gland Cancer

Effects of Adrenal Tumors – From the Dog’s Point of View

If an adrenal gland tumor is not functional – which means that it is not causing the adrenal cortex to secrete abnormally large amounts of corticosteroid hormones into the dog’s bloodstream - the affected animal usually will have no noticeable symptoms of disease or discomfort. Benign nonfunctional adenomas rarely cause any significant consequences.

When a tumor is functional, however; it will cause the affected adrenal gland or glands to make and release unusually high amounts of adrenal hormones into circulation. Within a fairly short period of time, most dogs that have functional adenomas or adenocarcinomas will start to feel increasingly sick. They will feel weak, listless and lethargic. They won’t feel hungry and will lose their appetite, causing them to lose weight and feel even weaker. They will be excessively thirsty. Put plainly, they will feel lousy. These are fairly non-specific signs that can be caused by many other disorders, which makes adrenal gland tumors somewhat difficult to diagnose.

Symptoms of Adrenal Tumors – What the Owner Sees

Owners of dogs with nonfunctional adrenal tumors almost never notice any signs or symptoms of discomfort or distress. However, owners of dogs with functional adenomas or adenocarcinomas may observe one or more of the following signs, depending on which layer of the adrenal cortex is affected:

  • Excessive water intake (polydipsia)
  • Increased urine output (polyuria)
  • Increased appetite and food intake (polyphagia; affected dogs are often ravenous)
  • Weight gain, frequently to the point of obesity
  • Abdominal enlargement (pendulous, distended abdomen; “pot-bellied” appearance)
  • Hair loss (alopecia; usually patchy and symmetrical on both sides of the body)
  • Darkening of skin (hyperpigmentation)
  • Excessive panting; often when lying down and appearing to be resting quietly
  • Skin bruising
  • Clitoral enlargement in females (clitoral hypertrophy)
  • Testicular enlargement in males (testicular hypertrophy)
  • Loss of normal reproductive cycling in females (anestrus)
  • Infertility (males and females)
  • Weakness
  • Lethargy, listlessness
  • Exercise intolerance
  • Muscle atrophy
  • Thin, fragile skin that tears easily
  • Poor coat condition
  • Lack of coordination (ataxia)
  • Neurological signs (circling, aimless wandering, pacing, bumping into walls or furniture, falling down for no apparent reason)
  • Poor wound healing

Dogs at Increased Risk

Functional tumors of the adrenal glands most commonly afflict middle-aged and older dogs, regardless of whether the masses are benign adenomas or malignant adenocarcinomas. As a result, when they start to notice some of the above symptoms, many owners are fooled into thinking that their beloved companions are just going through the natural effects of aging, which is completely understandable. Females and large-to-giant breed dogs also seem to have an elevated risk of developing adrenal masses. According to some reports, German Shepherds, Labrador Retrievers, Dachshunds, Poodles and some breeds from the Terrier Group may be predisposed to adrenal gland tumors, although the reasons for these associations are not well-understood.

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