Pituitary Tumors in Dogs

Pituitary tumors in dogs form on or near the pituitary gland, an important gland in the endocrine system. Pituitary tumors in dogs are often very small, but they can drastically impact pituitary function and cause serious hormone imbalances in dogs. Read on to learn more.

Your Dog's Pituitary Gland and What Is Does

Your dog's pituitary gland can be found at the back of his brain. The hormones it produces act on the adrenal and thyroid glands, whose hormones regulate metabolism. Pituitary hormones also help regulate your dog's sexual function.

How Tumors Affect Your Dog's Pituitary Function

Tumors on or near the pituitary gland are usually very small, even microscopic. Most pituitary tumors aren't cancerous, but they can cause your dog's pituitary gland to malfunction, leading to overproduction of hormones by other glands in the endocrine system. Cushings Disease, a metabolic disease in which the adrenal gland produces too many of its hormones, often occurs in dogs who develop pituitary tumors.

If your dog develops a pituitary tumor that begins to affect the function of his pituitary gland, he could develop some of the following symptoms:

  • Swelling of the abdomen

  • Thinning of the skin

  • Loss of hair

  • Increased appetite

  • Excessive thirst and increased urination

Some breeds are more likely than others to develop pituitary tumors. These breeds include Boxers, Dachshunds and Boston Terriers. Not all dogs with pituitary tumors develop symptoms of pituitary malfunction, however. Your dog may or may not suffer any ill effects, depending on the precise location of the tumor and its size.

Diagnosing Pituitary Tumors in Dogs

Your vet will probably need a CT scan or an MRI to definitively diagnose a pituitary tumor in your dog. Tests of these nature can, however, be expensive and they require general anesthesia, which may not be safe for all dogs experiencing symptoms. If your dog is suffering from symptoms of pituitary tumor, your vet may make a diagnosis based on his symptoms and recommend simply treating the symptoms, since the tumors themselves can be hard to remove.

Most pituitary tumors in dogs aren't cancerous and grow slowly. Surgery isn't useful for removing a canine pituitary tumor; the position of the pituitary gland in your dog's brain makes such tumors too difficult to access. Radiation therapy can be used to stop or slow the growth of a pituitary tumor if necessary; sometimes radiation therapy can eliminate small pituitary tumors. 

For most canine pituitary tumors, however, medication can be administered to treat the tumor and the symptoms. Chemotherapy drugs can reduce the size of pituitary tumors, often enough to relieve the symptoms they can cause. Your dog will need to be monitored closely during treatment with these drugs, to make sure he is responding well. Symptoms usually clear up within four to six months, though your dog might experience a relapse of symptoms later in life; most dogs need to continue taking medication for the rest of their lives to manage their symptoms.