MSD Manual

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Cathartic and Laxative Drugs

Cathartic and Laxative Drugs



Castor oil

Dogs: 5–25 mL, PO

Foals: 25–50 mL, PO


Dogs: 5–20 mg, PO, once to twice daily

Cats: 2.5–5 mg, PO, once to twice daily

Magnesium sulfate (Epsom salts)

Dogs: 5–25 g, PO

Cats: 2–5 g, PO

Horses: 30–100 g, PO

Magnesium hydroxide (milk of magnesia)

Dogs: 5–10 mL, PO

Cats: 2–6 mL, PO

Horses: 1–4 L, PO


Dogs: 5–15 mL, PO, tid

Cats: 2–3 mL, PO, tid

Docusate sodium, docusate calcium, docusate potassium

Dogs and cats: 2 mg/kg/day, PO

Horses: 10–20 mg/kg in 2 L water