Disorders of Calcium Metabolism in Dogs

Proper calcium levels are extremely important to the health of humans and animals. If the levels of calcium are not within the proper range, there can be devastating effects on your dog’s health and well-being. There are two types of calcium metabolism disorders that dogs experience. Treating these disorders is crucial in the health of the dog.

Calcium metabolism disorders occur when there is too little or too much calcium in the body. This can lead to serious complications for your dog.

Signs of calcium metabolism disorders will depend on the type of disorder the dog is experiencing and the duration of the condition. One or more of the following symptoms may be noticed:

• Panting and restlessness
• Twitching
• Muscle spasms and contractions
• Tremors, sometimes severe
• Lack of coordination
• Aggression
• Whining, drooling, and pacing
• Hypersensitivity
• Stiffness of muscles
• Disorientation
• Rapid heartbeat
• Fever, seizures, and coma in severe cases
• Increased thirst and urination
• Reduced appetite
• Vomiting
• Constipation
• Weakness
• Depression

Types

There are two main types of calcium metabolism disorders in dogs. Hypocalcemia is an abnormally low level of calcium in the blood. It creates major disturbances in central and peripheral nervous systems of the dog’s body. Hypercalcemia is an abnormally high level of calcium in the blood. It can be toxic to the dog’s body, especially in the cardiovascular system, the nervous system, and the kidneys.

Chronic kidney disease can be the cause hypocalcemia or hypercalcemia. This may include kidney disease or kidney failure. Kidney failure is the most common cause of hypocalcemia.

Pregnancy and nursing are sometimes a cause of hypocalcemia in female dogs. It usually occurs after giving birth, although signs can appear before or during the birth process.

Hypoparathyroidism is a cause of hypocalcemia. It is a diminished parathyroid hormone concentration in the blood of the dog.

Underactive adrenal gland is the cause of hypercalcemia.

Malignant tumors are the most common cause of persistent hypercalcemia. It is due to an increase in bone reabsorbing cells, tubular reabsorption in the kidneys, and increased absorption in the intestine.

Hyperparathyroidism is a cause of hypercalcemia. It is an excess of the parathyroid hormone concentration in the blood of the dog.

Granulomatous disease is an inherited immunodeficiency disease that can cause hypercalcemia in dogs.

Vitamin D overdose is sometimes a cause of hypercalcemia. Because vitamin D is a fat soluble vitamin, it can become toxic if given in excess, causing problems in calcium metabolism.

Ingestion of houseplants such as Triestum flavescens (oatgrass), Solanum malacoxylon, and Cestrum diumum (day-blooming jessamine) can cause hypercalcemia if ingested in significant quantities

Making an appointment with your dog’s veterinarian is a necessity if your dog is experiencing symptoms of a calcium metabolism disorder. Your dog’s health history will be considered, a list of symptoms evaluated, and a physical examination will performed to determine the diagnosis. If the symptoms are severe, your dog’s response to immediate treatment will be noted and may aid in giving a tentative diagnosis. Blood serum tests and urine tests will be performed and will be needed in order to check the calcium levels and parathyroid levels of the dog and to confirm the diagnosis of a calcium metabolism disorder. If the symptoms are suspicious and suggest possible other conditions, those conditions will be ruled out before a disorder is diagnosed. If parathyroidism is suspected, the parathyroid glands will be examined with an ultrasound. Sometimes a thyroidectomy will have to be performed if the parathyroid glands are not detected.

Returning blood calcium levels back to normal is the treatment goal. The underlying cause must always be identified and eliminated. 

Treatment of Hypercalcemia

Hypercalcemia is treated by treating the underlying condition that is causing it. Sometimes no cause can be found. Mild hypercalcemia is not necessarily dangerous, but a more severe condition often times requires immediate veterinary attention. Fluids, diuretics (“water pills”), glucocorticoids (a class of steroid hormones), and sodium bicarbonate are common treatments for hypercalcemia. These treatments lower the level of calcium in the blood. 

Treatment of Hypocalcemia

Hypocalcemia is treated by restoring the low level of calcium in the blood back to normal. Intravenous calcium is needed immediately if the dog is experiencing muscle spasms or seizures. In the case of parathyroidism, surgical exploration of the neck and removing the abnormal parathyroid tissue may be recommended. Calcium supplements and vitamin D are used for long term treatment of hypocalcemia. Care must be taken not to over treat hypocalcemia, because of the complication of it developing into hypercalcemia. Always follow the exact recommendations of your veterinarian regarding the treatment of this disorder.

How your dog’s calcium metabolism disorder is managed will be determined by the cause. If your veterinarian prescribes daily oral calcium and vitamin D preparations to keep calcium levels within the normal range, follow the exact directions to prevent toxicity. If the disorder was caused by birthing and nursing, the likelihood of recurrence in future pregnancies is great. Feeding a high-quality food that is appropriate for pregnancy and lactation may help to prevent future occurrences. If your dog had abnormal parathyroid tissue surgically removed, medications will be prescribed according to the final diagnosis and a proper treatment plan will be advised.