Hypercalcemia in Dogs

Calcium is essential for blood clotting, cardiovascular, neuromuscular, immune and endocrine function.  Bones need calcium to keep them healthy and strong. If the bones lose too much calcium because it is going instead into the bloodstream, they will become weak. The bones of the canine will be more susceptible to bone fractures. 

Calcium levels are controlled and monitored by the parathyroid glands. The parathyroid hormones and vitamin D interact to release calcium from the bones, stomach, and kidneys, which is then transferred to the canine’s bloodstream.

High levels of calcium in your canine’s bloodstream can be toxic to all of his body tissues. Hypercalcemia will also be harmful to the kidneys, nervous and cardiovascular system.  High calcium levels may also bring on gastrointestinal problems, acute renal failure, coma, and even death if not treated.

If you notice that your dog is not himself and is experiencing any of the symptoms for hypercalcemia, please take your pet to the veterinarian.  The longer high calcium levels in the bloodstream are left untreated, the more damage it is causing to your pet’s health.

Hypercalcemia in dogs means that the level of calcium in the canine’s bloodstream is abnormally high. High calcium levels can be a secondary symptom associated with serious diseases such as Addison’s disease, kidney failure, parathyroid gland tumor and cancer.

Symptoms of hypercalcemia may include one or more of the following signs:

• Dehydration
• Excess thirst
• Frequent urination
• Loss of appetite
• Weakness
• Formation of bladder or kidney stones
• Vomiting 
• Weight loss
• Constipation
• Swelling of the lymph nodes

• Canine lymphoma 
• Anal gland cancer
• Addison’s disease
• Kidney failure
• Exposure to too much vitamin D (can be found in plants, poisons or topical ointments)
• Dehydration
• Hypercalcemia may be a side effect of certain medications, alkaline antacids, long-term use of diuretics, estrogens, and progesterone 
• Anemia

The veterinarian will ask for a thorough medical history on your dog.  He will ask you when the symptoms you have observed commenced. Let your veterinarian know if your pet is on any supplements or medicines.  The physical examination may include palpation of the lymph nodes and abdomen.  He may also check your canine’s anal sacs to search for masses; one of the causes of hypercalcemia is cancer of the anal sac glands. Diagnostic tests that your veterinarian may recommend:

• Bloodwork (serum biochemistry profile and complete blood count)
• Urine sample to show if there is damage to the kidneys
• Parathyroid hormone test (PTH)  
• Thoracic and abdominal x-rays can show the presence of a mass
• An ultrasound of the parathyroid will evaluate the shape and size of the parathyroid glands 
• An ACTH stimulation test will exclude Addison’s disease in your dog 
• Blood ionized calcium concentration to assess the biologically active form of calcium

The treatment for hypercalcemia depends on what information the physical, blood work, and diagnostic test revealed.  If your veterinarian determines that your pet is dehydrated, it will be necessary to rehydrate him by administering fluids by intravenous or subcutaneously (under the skin). If the blood concentration is very high in the bloodstream, your veterinarian team may recommend hospitalization in order to start drug treatment. If your pet is diagnosed with cancer, surgery and chemotherapy may necessary.  

Loop diuretics such as furosemide can increase calcium excretion by the kidneys. Diphosphonates may be prescribed to minimize the bone release of calcium.  Glucocorticoids such as dexamethasone or prednisone may be administered if there is no adequate response to IV fluids with furosemide.  Prednisone and other corticosteroids can reduce calcium absorption. Long term control of hypercalcemia may include drugs such as bisphosphonate, mithramycin, or calcitonin.

Canines that undergo surgery will receive post-operative instructions from the surgeon.  Your dog will be given pain medication, and it will be very important to limit your pet’s activity, usually for 3 weeks after surgery. If you notice twitching muscles, dilated pupils, weakness or seizures, please call your veterinarian. If the biopsy taken during surgery revealed cancer the surgeon may recommend ongoing low-dose chemotherapy, called metronomic therapy, to keep the cancer in check. It is very important to follow the treatment plan that your veterinarian team has recommended for your companion.