Magnesium Sulfate - Epsom Salts

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mag-NE-ze-um SUL-fate - Pronunciation guide

Brand Names

  • Cooper's Best Epsom Salt Poultice


Magnesium sulfate is useful in several ways in the horse stable. Given its saline properties, its ability to be absorbed into the skin, its laxative properties, and its cleansing properties, as well as its ready availability and low cost, it serves several purposes.

Magnesium Sulfate IV is used to treat cases of anti-arrhythmics in equines.


Magnesium Sulfate in IV form is used to treat ventricular tachycardia and in the management of ventricular arrhythmias not responsive to other antiarrhythmic agents.

In foals, it is used to treat perinatal asphyxia syndrome.

Magnesium sulfate is commonly used as a laxative and a wound soak for horses. In the gel form available from many veterinarian supply sources, it is reported to be very useful in significant and lasting reduction of pain in the horse's limbs. Magnesium sulfate paste is sometimes used as an agent in drawing boils and carbuncles. Used in soaking wounds, it helps clean and soothe the tissues and skin.

Magnesium sulfate may also be used as a supplemental source of magnesium in the diet of horses.

Dosage and Administration

Magnesium Sulfate
Method Dosage Concentration Period Duration
As an oral laxative
Oral or Nasogastric tube 1-4 mg/kg Dissolve in 1 (foal) to 4 (adult) liters warm water Daily NA
As an hoof poultice1
Topical As needed Moisten with warm water to form a paste2 36-48 hours NA
As an drawing soak1
Foot bath As needed Add to 4 liters warm water as much Epsom Salt as will dissolve. 10-15 minutes 2 times a day 2 or 3 days


  • Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian).
  • 1For the treatment of mild lameness due to hoof abscess or bruise. Severe lameness requires veterinary care immediately. Hoof abscess can be extremely painful and stressful for the horse.
  • 2 Pack the entire sole and frog to draw abscesses or address sole bruising. Cover with a wrap or boot and let draw for 36 to 48 hours. If condition persists or if irritation develops, discontinue use and consult a veterinarian.

Side Effects

Excessive use may lead to diarrhea.


Excessive magnesium will be excreted in the urine, but too much may cause renal problems.


Do not use magnesium- plus calcium-containing solutions when given as IV.


May cause renal problems and diarrhea.


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About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.