Primary hyperparathyroidism is a disorder resulting from excessive secretion of parathyroid hormone (PTH) by one or more of the parathyroid glands located in the neck. The excessive amounts of PTH cause an elevated calcium level in the bloodstream, and this can have harmful effects on the body and can make dogs and cats ill.

The most common cause of primary hyperparathyroidism is a single benign tumor, called an adenoma, on one of the parathyroid glands. Malignant tumors of the parathyroid gland are much less common.

Primary hyperparathyroidism is much more frequently diagnosed in dogs as compared to cats. Older dogs are more commonly affected (average age is 10 years). Males and females are equally affected. Keeshonds have a higher incidence than other breeds. A genetic marker associated with primary hyperparathyroidism has been found in the Keeshond.

Veterinarians can submit tests to determine the likelihood of disease in individual Keeshound dogs. The goal is for breeders to use test results to make breeding decisions and to eventually eliminate the disease from the breed. Test inquires can be submitted through the Cornell Animal Health Diagnostic Center. For more information, visit the lab's Web site at www.vet.cornell.edu/faculty/Goldstein.

At first, the mildly elevated calcium levels don't cause any symptoms. As time progresses and the calcium levels continue to rise, clinical symptoms appear. Three main body systems are usually affected: the gastrointestinal system, the kidneys, and the nervous system.

What to Watch For

Excessive thirst and urination

Listlessness

Weakness or intolerance to exercise

Poor appetite

Shivering

Loss of muscle mass

Vomiting

Constipation

Stiff gait

Difficult or abnormal urination, such as straining, bloody urine, increased frequency of urination

Diagnosis

A complete medical history and physical examination

Blood tests will be necessary to confirm the elevated calcium levels

Urinalysis

Ultrasound of the neck, as well as other affected organ systems

X-rays

An electrocardiogram to trace the electrical activity of the heart

Treatment

Treatments for primary hyperparathyroidism may include the following:

Surgical removal of the abnormal parathyroid gland

Hospital admission and administration of intravenous fluids and various medications may be necessary in cases where the calcium level in the bloodstream is dangerously high

Home Care and Prevention

Give medications as directed. If the abnormal parathyroid gland was surgically removed, dogs will occasionally develop signs of LOW calcium 1 to 7 days post-operatively. Carefully monitor your pet at home for signs of low calcium, including panting, nervousness, muscle twitching, leg cramping, stiff gait and seizures.

There is no known cause for primary hyperparathyroidism, therefore, there is no preventative care.