Hypermagnesemia

Definition: A condition where plasma magnesium (Mg) concentration exceeds 2 mg/dL (1.1 mmol/L).

Prevalence: It is considered a rare condition.

Susceptibility: Primarily reported in monogastric animals.

In Horses: Often results from excessive oral doses of magnesium sulfate administered as a cathartic to treat large-intestinal impactions.

In Cats: Reported in feline patients with renal failure that are receiving IV fluid treatment.

>2.5 mmol/L: Electrocardiogram (ECG) changes, specifically prolongation of the PR interval.

>5 mmol/L:

• Loss of deep tendon reflexes.

• Hypotension (low blood pressure).

• Respiratory depression.

>6.0–7.5 mmol/L: High risk of cardiac arrest.

Primary Intervention: Clinical signs generally subside following a slow IV infusion of calcium gluconate (typically a 23% solution).