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Hypercalcemia in Dogs

Posted March 07, 2014 in Dog Diseases & Conditions A-Z

As little children our parents implore us to drink our milk so we will grow big and strong with healthy bones and pearly, white teeth. Later we are admonished to eat plenty of leafy greens and to consider taking calcium supplements as we start worrying about our aging, brittle bones. Manufacturers even fortify other food staples like orange juice, bread and cereal to get more calcium in our diets. That must mean that you or your dogs simply can’t get too much of this good thing, right?

Can a dog have too much calcium?
Unless you or your dog is taking supplements containing high doses of calcium, it is unusual to develop abnormally elevated calcium levels or hypercalcemia due to dietary intake. There are, however, many other medical situations/conditions where calcium levels can increase enough to result in serious and possibly life-threatening consequences — involving the other complex, physiological functions: blood clotting, nerve impulse conduction, and heart muscle contractions.

What causes elevated calcium levels in dogs?
The following is Dr. Mark E. Peterson’s top-10 list:

  • Spurious (fat in the serum causing false elevation of calcium)
  • Lymphosarcoma  
  • Hypoadrenocorticism (Addison's disease)
  • Primary hyperparathyroidism (parathyroid tumor)
  • Renal failure
  • Vitamin D toxicosis
  • Apocrine gland carcinoma (tumor) of the anal sac  
  • Multiple myeloma of bone (10-15% of cases have high calcium)
  • Other carcinomas (e.g., lung, mammary, nasal, pancreatic, thymic, thyroid, testicular)
  • Granulomatous diseases (caused by different infectious agents)

In addition, you should be aware that some drugs including certain diuretics and antacids and some rodenticides (rat poisons) can cause hypercalcemia so be sure your veterinarian is aware of any medications your dog is taking or might have had access to.

What are the signs of hypercalcemia in dogs?
Hypercalcemia is not common in any species but is encountered more often in dogs than in cats. As is so often the case in veterinary medicine, clinical signs of hypercalcemia can be very vague and nonspecific:

  • Increased thirst and urination
  • Decreased appetite
  • Lethargy and depression
  • Gastrointestinal upset causing vomiting
  • Abdominal pain and/or constipation

Kidney failure can occur as a result of hypercalcemia and then compound the problem as a further cause of imbalance. Disturbances in nerve conductivity and cardiac muscle contractions can ultimately cause neurologic tremors or seizures, weakness, and cardiac arrhythmias. If the levels remain significantly elevated, calcium can be deposited in any soft tissue or organ system in the body. Left untreated, hypercalcemia

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Mike has more than 35 years of experience in companion animal veterinary practice and is a valued member of IDEXX’s Pet Health Network team since 2013.