Excess Magnesium in the Blood in Dogs

By PetMD Editorial on Mar. 26, 2010

Hypermagnesemia in Dogs

Magnesium is found mostly in bones and muscles, and is required for many smooth metabolic functions. However, abnormally high levels of magnesium in the blood can result in serious complications, like impaired nerve impulses and cardiac problems. This health issue is called hypermagnesemia.

Symptoms and Types

Hypermagnesemia leads to the progressive loss of respiratory, cardiovascular, nervous, and muscle functions -- all of which can be fatal in the dog. Other symptoms associated with this issue include:

  • Nausea
  • Vomiting
  • Weakness
  • Lowered heart rate
  • Paralysis
  • Mental depression
  • Poor reflexes
  • Respiratory depression
  • Cardiac arrest
  • Coma


  • Kidney failure
  • Poor intestinal motility
  • Constipation
  • Administration of high levels of magnesium
  • Endocrine disorders (e.g., hypoadrenocorticism, hypothyroidism, hyperparathyroidism)


After recording a detailed history from you, the veterinarian will perform a complete physical examination. Routine laboratory tests include: a complete blood count, biochemistry profile, and urinalysis. These tests help determine the levels of magnesium in the blood, which will record more than normal in affected dogs. Abnormally high levels of calcium are also found in affected dogs. As hypermagnesemia mostly occurs in patients with kidney problems, urinalysis and other laboratory tests may reveal abnormalities related to an underlying disease. Additionally, your veterinarian will perform an electrocardiography (ECG), as characteristic ECG changes are seen in patients with hypermagnesemia.


The major goal of treatment is to enhance the elimination of extra magnesium from the body. Therefore, all medications containing magnesium will be discontinued to prevent further aggravation of symptoms. Fluid therapy will be started to enhance the excretion of magnesium from the body of your dog. Calcium is also added in your dog’s therapy to enhance the excretion of magnesium.

During and/or after treatment, your veterinarian will conduct laboratory testing to see the levels of magnesium. An ECG will be conducted to see the dog's cardiac functions.

Living and Management

Prognosis in dogs with hypermagnesemia without kidney involvement is excellent after initial therapy. In cases of kidney disease, on the other hand, treating the underlying disease is essential for resolution of the problem on a permanent basis. Levels of magnesium will be monitored during and after the treatment. After discharge, if you see any untoward signs, immediately call your cat’s veterinarian.

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