High Calcium in Dogs' Blood

High calcium is also known as hypercalcemia and refers to the calcium concentration in the blood.The normal value for blood calcium concentration in adult dogs is from 9.0 to 11.6 mg./dl. This concentration can be a bit higher in puppies.

Causes of High Calcium in Dogs

The calcium level in the blood is controlled by two hormones: the parathyroid hormone and calcitrion. The interaction of these two substances helps the release of calcium from the bones, gut and kidney. When this interaction is disturbed or when cancerous cells secret hormones that interfere with the calcium regulation process, hypercalcemia can result. Some frequent causes of hypercalcemia are:

• Hyperparathyroidism or the hyperactivity of the parathyroid glands
• Different types of cancer
• Bone diseases
• Kidney failure
• Vitamin D poisoning from rodenticides, plants or food
• Aluminum toxicity

Blood samples are essential for a correct diagnosis. Some situations can cause erroneously high calcium concentrations:

• Dehydration 
• Lipemia, when the blood samples have a high fat content (i.e after a meal)
• Hemolysis
• Certain anti-coagulants and detergents used to clean  the glass from the lab also can cause high calcium concentration

Dog Symptoms of Hypercalcemia

The symptoms of hypercalcemia are non-specific, so diagnostic tests have to be done to exclude other diseases causing similar symptoms:

• Lack of energy/fatigue
• Weight loss
• Increased thirst
• Increased urination
• Weakness
• Vomiting
• Decreased gastro-intestinal function
• Depression
• Enlarged lymph nodes
• Hypertension
• Bladder stones
• Coma in severe cases

Diagnosing High Calcium in Dogs

If hypercalcemia persists after the correction of lipemia, hemolysis and dehydration a complete diagnostic evaluation has to be done to detect the real cause of high calcium levels:

• A complete medical history as well as a complex physical examination is required. Palpation of the neck, abdomen, the lymph nodes and the anal sacs will reveal the enlargement of the respective organs, that might lead to a hidden tumor
• A complete blood count will evaluate the red blood cell count, the total concentration of calcium, the level of ionized calcium
• A PTH level test that will show how the parathyroid glands function
• An ACTH stimulation test will exclude Addison’s disease in your dog which is an adrenal hormone deficiency
• Serum biochemistry tests may prove useful to appreciate your dog’s general health and also to see the effects of hypercalcemia on organs
• An urinalysis will show how can the kidneys concentrate the urine

Treatment Options for Dogs with High Calcium

The treatment will depend on the underlying cause, the severity of hypercalcemia and its effect on kidney function. When the calcemia is very high your pet may need:

• Emergency treatment, involving intravenous fluid therapy in hospital, otherwise the kidney will be affected and the soft tissues may be mineralized
• Low doses of furosemide also help remove calcium from the bloodstream
• Prednisone (a cortisone-like drug) helps the kidney to eliminate extra calcium and brings the calcium level to normal
• Diphosphonates help the bone release of calcium
• Drugs like mithramycin, calcitonin or ethylenediemetetraacetic acid are used to treat refractory hypercalcemia