Magnesium

       Sources:

Toxicity mostly developed due to high dose of minerals supplements or due to inappropriate supplement feeding. Animals living in areas where vitamins and mineral supplements are stored are at higher risk. Toxicity might develop due to ingestion of plastic bags used to store medications. Animal encountered with renal failure, endocrinopathies are also susceptible to Mg toxicity.

Mode of action:

Mg++ is competitive antagonist of Ca ++ and competes with Ca++ at the neuromuscular junction and blocks the release of acetylcholine (inhibition of acetylcholine-Ca++dependent release). Consequence is skeletal muscle paralysis.

Kinetics:

Mg is absorbed actively or passively from the intestines.

Kidney is essential for Mg homeostasis and is responsible for filtration, excretion and reabsorption.

Clinical signs:

• Gastrointestinal – vomiting, diarrhea, anorexia
• Nervous – flaccid paralysis
• Renal/urological – pain on abdominal palpation, uroliths
• Sweating, muscle weakness, rapid breathing and heartbeat (acute hypermagnesemia)

Diagnosis:

• Serum Mg level >3mg/dl (cats) and >2.5mg/dl (dogs).

Treatment:

• Emesis should be induced (in case of ingestion near toxic dose) and activated charcoal with a cathartic should be administered.
• Intravenous fluids to manage hydration and prevent hypovolemia
• Ca gluconate (10%) at 0.5 -1.5 mg/kg slow IV for 15–3o minutes.

Differential diagnosis:

• Vomiting, diarrhea, anorexia due to other GIT diseases

• Neurological diseases