Excess Magnesium in the Blood in Cats

By PetMD Editorial on Mar. 26, 2010

Hypermagnesemia in Cats


Electrolytes are required in the body for many vital functions, like keeping fluid balance, normal heart and brain functions, delivery of oxygen, and many more. Magnesium, after potassium, is the second most abundant positively charged electrolyte found inside cells. Bones and muscles contain a major portion of magnesium in the body. Hypermagnesemia is the term used to denote abnormally high levels of magnesium in the body. Higher levels of magnesium can result in serious complications like impaired nerve impulses (signals), as well as cardiac problems.


It is uncommon in cats, mostly seen in patients with underlying kidney diseases. High level of magnesium may result in life-threatening conditions, including those of the nervous system and the heart.


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 cats. Abnormally high levels of calcium are also found in affected cats. 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. 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 cat. Calcium is also added in your cat’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 cardiac functions.


Living and Management


Prognosis in cats 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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