The short version
The pituitary gland is located near the center and bottom of the brain. It produces a number of critical hormones that control many parts of the body, including several other endocrine glands. Because of this central role, it is sometimes called a “master gland.” Because large numbers of hormones are produced by the pituitary gland, a variety of different conditions can be caused by pituitary disease or tumors. The specific illness and signs depend on the cause and the area(s) of the pituitary gland that is affected.
Cushing Disease
Cushing disease, also called hyperadrenocorticism, is caused by too much cortisol. Miniature Poodles, Dachshunds, Boxers, Boston Terriers, and Beagles are at increased risk. In most affected dogs (85 to 90%), the cause is a small, benign pituitary tumor. In the remaining 10 to 15% of dogs, the cause is a tumor of the adrenal gland itself.
This condition tends to occur in middle-aged to older dogs. Common signs include increased thirst and urination, increased appetite, heat intolerance, lethargy, a “potbelly,” panting, obesity, weakness, thin skin, hair loss, and bruising. Rarely, calcinosis cutis develops, a condition in which minerals are deposited in the skin and can appear as small, thickened “dots” on the abdomen.
Diagnosis of Cushing disease can be difficult because laboratory test results may be inconclusive and false-positive test results are common in dogs that have other diseases. Veterinarians will run routine and specialized blood and urine tests on dogs that have signs of Cushing disease. Retesting may be needed 3 to 6 months later if test results are inconclusive or if the dog does not continue to show signs. Once the disease is confirmed, additional laboratory tests are usually done to determine whether the cause is a tumor of the pituitary gland or of the adrenal gland. The pituitary and adrenal glands can be further evaluated using abdominal x-rays, ultrasonography, or more sophisticated methods of diagnostic imaging such as computed tomography (CT) or magnetic resonance imaging (MRI).
Adult-onset Panhypopituitarism
In adult-onset panhypopituitarism, the pituitary gland and nearby tissues, including the hypothalamus, are compressed or damaged. As a result of this damage, the secretion of many of the anterior pituitary hormones becomes inadequate or absent. This disrupts a number of other hormone-producing glands, resulting in a variety of signs.
Inactive pituitary tumors develop most commonly in adult to older dogs. All breeds appear to be equally affected. Other conditions, infections, or injuries that lead to destruction of pituitary tissue can also cause panhypopituitarism.
Affected dogs are often depressed and uncoordinated, collapse with exercise, and lose weight. Occasionally, they show a change in attitude, do not respond to people, and tend to hide. In chronic cases, the animal may become blind because the growing pituitary tumor puts pressure on the optic nerves. Animals with panhypopituitarism appear dehydrated despite drinking more water. Dogs may urinate in large volumes and break housetraining.
Juvenile-onset Panhypopituitarism (Pituitary Dwarfism)
In juvenile-onset panhypopituitarism, also called pituitary dwarfism, the front portion of the pituitary gland does not fully develop or is disrupted by a tumor. This affects several other hormone-producing glands, leading to a variety of signs. In particular, the lack of growth hormone causes the young animal to be dwarfed.
Pituitary dwarfism is most common in German Shepherds and has been seen in the Spitz, Miniature Pinscher, and Karelian Bear Dog. It is inherited and occurs equally in male and female dogs.
Dwarf pups appear the same as their normal littermates up to about 2 months of age. After that, they grow slower than their littermates and keep their puppy coat. Primary guard hairs do not develop. Hair is gradually lost on both sides of the body, and hair loss often becomes complete except for the head and tufts of hair on the legs. Permanent teeth do not come in, or come in late. Closure of the growing ends of the bones can be delayed as long as 4 years. The testes and penis of male dogs are small. In female dogs, heat cycles are irregular or absent. Because the pituitary gland affects the production of other hormones in the body, the levels of thyroid hormones and cortisol are reduced, and the thyroid and adrenal glands show signs of deterioration. Affected dogs have a shortened life span.
Diabetes Insipidus
Despite its name, diabetes insipidus is not related to the more commonly known diabetes mellitus, and it does not involve insulin or sugar metabolism.
Diabetes insipidus is caused by problems with antidiuretic hormone or vasopressin, a pituitary gland hormone responsible for maintaining the correct level of fluid in the body. Either the pituitary gland does not secrete enough of this hormone (called central diabetes insipidus), or the kidneys do not respond normally to the hormone (called nephrogenic diabetes insipidus).
Affected dogs urinate in large volumes and drink equally large amounts of water. The urine is very dilute even if the animal is deprived of water. (Normally, urine becomes more concentrated when an animal is dehydrated.)
Frequently asked questions
Diseases of the pituitary gland in dogs?
The Merck Veterinary Manual covers this in the article linked on this page. The pituitary gland is located near the center and bottom of the brain. It produces a number of critical hormones that control many parts of the body… If your dog is unwell, contact your veterinarian — this page is educational, not a diagnosis.
Pituitary gland problems in dogs?
The Merck Veterinary Manual covers this in the article linked on this page. The pituitary gland is located near the center and bottom of the brain. It produces a number of critical hormones that control many parts of the body… If your dog is unwell, contact your veterinarian — this page is educational, not a diagnosis.