Excess Calcium in the Blood in Dogs

Many canines with excess calcium in the blood become very sick, while others show no symptoms of the condition. Calcium is essential to critical bodily functions like bone growth and muscle contraction, but an overabundance may be secondary to an underlying disease and can also contribute to urolithiasis (the formation of stones in the kidneys, bladder or urinary tract). Having excess calcium in the blood can cause damage to all areas of the body and the extent of the harm will depend on the how extreme the increase is, and how long your pet has been experiencing the condition. Prompt treatment for your canine companion  is necessary in order to avoid significant complications that could make him very ill.

Excess calcium in the blood is defined as hypercalcemia in veterinary terms. While calcium does play an important role in the body, excessive amounts can signify the presence of a serious underlying disease such as cancer or kidney failure.

Although some canines may be asymptomatic when their blood contains too much calcium, others will become very sick. Hypercalcemia hinders the ability to concentrate urine and also leads to excess thirst. The symptoms will vary depending on how severe the hypercalcemia has become.

• Extreme thirst (polydipsia)
• High production of diluted urine (polyuria)
• Pain when urinating (dysuria)
• Blood in the urine (hematuria)
• Frequent urination which may come only in drops (stranguria)
• Muscle weakness
• Muscle twitching
• Listlessness
• Low appetite
• Dehydration
• Depression
• Constipation
• Low activity tolerance
• Seizures
• Collapse

Secondary illnesses may manifest additional symptoms related to the specific condition.

Types

Blood Calcium is either referred to as total blood calcium (attached to proteins), or ionized (not attached to proteins, and also known as free calcium). All cells need calcium in order to function properly.

The number of reasons why your pet may suffer from an excess of calcium in the blood are many, with cancer being the number one cause. 

• Apocrine gland sarcoma of the anal sac
• Multiple myeloma
• Carcinomas like pancreatic 
• Lymphosarcoma
• Ingestion of certain plants
• Hyperparathyroidism
• Hyperadrenocorticism (Addison’s disease)
• Ingestion of excessive Vitamin D in supplements or medicines
• Bone disease
• Fungal infection
• Dehydration
• Granulomatous disease like histoplasmosis
• Azotemia (accumulation of large amounts of nitrogenous waste products in the blood)

The veterinary team will require a complete recent history of the events leading to the visit. Be as accurate as you can when relaying information about the symptoms you have noticed, and the approximate time frame for when you began to see changes in your pet’s demeanor and state of health.

There are many causes for excess calcium in the blood, and therefore the number of possible tests that can be ordered varies greatly also. First, a complete physical examination will be done, to begin the overall analysis of your pet’s health.

Tests that may be included in the diagnostic process are listed below.

Blood tests

• Complete blood count and serum biochemistry profile
• Calcium levels are checked within a biochemistry profile. This may include both ionised and un-ionised.
• The calcium test should be repeated after a 12 hour fast for optimum accuracy
• The veterinarian will check for Addison’s disease by assessing salt and cortisol levels
• Vitamin D levels may be analysed
• Verification of the presence of fungus is important

Assay of PTH or PTHrP

• PTH can indicate if the parathyroid glands are causing the hypercalcaemia
• PTHrP test can be used to confirm hypercalcaemia with malignancies like apocrine gland adenocarcinoma of the anal sac

Urinalysis

• This test can indicate if the kidneys are functioning normally
• The presence of blood and the concentration of urine will be studied

Imaging Tests

• An MRI scan, radiographs and/or ultrasound scans can reveal cancer or bone damage

Other diagnostic tools like cytology, biopsy, or histology could be needed as well.

Treatment for the excess calcium in the blood will initially depend on the condition of your beloved pet when he arrives at the clinic. The main impact on your dog’s health in the immediate will be regaining the function of elimination of calcium from the urine, and to stop the removal of calcium from the bones.

Your dog may need intravenous or diuretic therapy if he is dehydrated, or if renal function needs to be supported. Glucocorticoids will also be administered if needed to balance the calcium function and resorption. Medication to decrease serum calcium or inhibit bone resorption could be prescribed. 

In cases of a secondary illness which may be causing the excess calcium, improvement will be seen when the problem is addressed. For example, treatment for hypoadrenocorticism, if that is the cause, will resolve the hypercalcemia. In the instance of a malignancy, surgery or chemotherapy and radiation might be the required method of treatment.

Once serum calcium concentrations are normalised, your pet will be on the road to recovery. If too much supplementation of Vitamin D was the problem, for example, simply removing the additive will help to eradicate the problem. In the event of a malignancy, the treatment and recovery will be more extensive. However, it must be noted that when cancer is causing the hypercalcemia, the positive prognosis is much lower because tumors often recur and survival time is low.