Tumors of the Endocrine Glands in Dogs

Your dog’s endocrine glands are the adrenal glands, thyroid gland, pituitary gland, and parathyroid glands. These glands are what controls the hormones in your dog’s body, and when there is a tumor in any of these areas, it often causes an increase in hormones. The hormones are what keeps the right amount of fluids and chemicals in certain parts of the body, and when a tumor is involved, the levels of these chemicals can increase or decrease rapidly. This is what usually causes another disorder that brings on the symptoms you will notice. For example, if there is a tumor in the thyroid gland (in the front of your dog’s neck), it can cause hyperthyroidism, which produces symptoms of restlessness, increased urination, and weight loss. Since there are different endocrine glands in your dog’s body, the types of tumors, symptoms, and treatments are dependent on which gland is involved.

Endocrine tumors (endocrine gland tumors) develop when your dog’s hormonal system is out of control, and cannot produce enough differentiated cells. Endocrine gland tumors can form in any part of the endocrine system in your dog, which includes the pituitary gland, parathyroid gland, thyroid gland, adrenal glands, pancreas, and reproductive organs (ovaries or testes).

The symptoms depend on where the tumor is located:

Adrenal glands

• Increased appetite and thirst
• Loss of hair
• Dry skin
• Lumps on neck and back from calcium deposits
• Diabetes
• Irritability
• Depression
• Confusion
• Nervousness

Thyroid gland

• Fatigue
• Redness and warmth of the face
• Sweating
• Headaches
• Nausea

Pituitary gland

• Vomiting
• Diarrhea
• Decreased or increased appetite and weight
• Swollen abdomen
• Changes in bowel or bladder habits

Parathyroid glands

• Loss of appetite
• Nausea and vomiting
• Constipation and abdominal pain
• Increased thirst and frequent urination
• Fatigue, weakness, and muscle pain
• Confusion, disorientation, and difficulty thinking
• Headaches
• Fever

 Types

• Adrenal gland tumors
• Pancreatic tumor
• Parathyroid gland tumors
• Pituitary gland tumors
• Thyroid tumor

The cause of endocrine tumors is unknown, although they seem to affect older dogs (over seven years old) most often. This condition causes an extreme increase in hormones that triggers secondary diseases in your dog, such as Cushing’s disease, diabetes, hypothyroidism, hyperthyroidism, and various cardiac and renal diseases. The most common types of endocrine diseases are overproduction of hormones from endocrine tumors.

Your veterinarian will do a physical examination of your dog that includes body temperature, weight, height, heart rate, respirations, blood pressure, and reflexes. He will do some neurological tests to see if your dog’s sensory and motor skills are normal, as well as balance, coordination, and cognition. Laboratory tests, such as complete blood count, blood chemistry profile, glucose levels, urinalysis, and fecal examination are also standard tests that provide excellent diagnostic information.

A fine needle aspiration will be done if it is possible to remove cells from the tumor for analysis. This will let the veterinarian know if the tumor is cancerous. An MRI, ultrasound, CT scan, and x-ray will be done to determine the areas affected by the tumor and to see if it has spread.Your dog’s medical history is usually needed to inform the veterinarian of any illnesses or injuries your dog has had and if his immunizations are up to date. Be sure to let him know if there has been any strange behavior or change in appetite.

The best treatment for any kind of tumor is surgical removal, but sometimes that is not an option. Sometimes, it may be necessary to remove the gland as well as the tumor, in which case your dog will need medication indefinitely to regulate his hormones. In some cases, the tumor may be unable to be removed, such as when it has integrated itself into a vital organ or if it has already metastasized. In these cases, chemotherapy may be suggested if your dog is in relatively good health otherwise, but these tumors are hard to treat with chemotherapy alone.

If the tumor is small and has not spread, the veterinarian may decide to use radiofrequency ablation (RFA) to kill the cancer cells. This procedure is done by sending a current of high temperature through a tiny needle into the tumor, which has been very successful in the past, and is less invasive than surgery.

If your veterinarian is able to remove the entire tumor without damaging the endocrine glands, the chances of your dog’s survival is excellent. Although there is a chance for the tumor to recur, if you and the veterinarian are able to catch it early enough, another treatment can virtually eliminate the chances of a recurrence. Be sure to follow up with your veterinarian regularly and contact him if there are any signs of the tumor returning.