Acetazolamide: veterinary dose and monograph

At a glance

Drug class

Diuretic

Also known as

Diamox, Iopar, Acetazolamide

Species with doses

Dogs, Cats and Horses

General dose range

4–10 mg/kg PO q8–12h — check the species tables for the indication

Routes

PO

Last reviewed

1 October 2026

Indications

• Glaucoma — reduce intra-ocular pressure (aqueous humour suppression)
• Hyperkalaemic periodic paralysis (HYPP) in horses — prevention of attacks
• Metabolic alkalosis (bicarbonate diuresis)
• Adjunct in some CSF/oedema/altitude conditions

Acetazolamide dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Glaucoma / metabolic alkalosis: Papich 5e: glaucoma 5–10 mg/kg PO q8–12h; other diuretic uses 4–8 mg/kg q8–12h (the veterinary label listed 10–30 mg/kg). Plumb’s p.26: glaucoma 10–25 mg/kg divided 2–3 times daily (Brooks); 7 mg/kg PO q8h (Vestre); metabolic alkalosis 10 mg/kg four times daily (Hardy). Topical carbonic-anhydrase inhibitors are preferred long-term for glaucoma; monitor potassium and acid–base.
• Hydrocephalus (paediatric, adjunct): Plumb’s p.26 (Coates 2002): 0.1 mg/kg PO q8h. Monitor electrolytes.

Cats

• Glaucoma (adjunct): Papich 5e and Plumb’s p.26 (Vestre 1985): 7 mg/kg PO q8h. Topical dorzolamide or brinzolamide is usually preferred; monitor electrolytes.

Horses

• Hyperkalaemic periodic paralysis (HYPP): Plumb’s p.26: 2.2–4.4 mg/kg PO q12h (Schott); 0.5–2.2 mg/kg q12h (Mayhew); 2–3 mg/kg PO q8–12h when diet alone fails (Valberg). Papich 5e lists higher doses — 4 mg/kg IV or 8 mg/kg PO q8–12h. Combine with a low-potassium diet. ARCI Class 4.

Contraindications

Significant hepatic disease (can precipitate hepatic encephalopathy by altering ammonia handling), severe renal impairment, hypokalaemia/hyponatraemia, and metabolic acidosis. Sulfonamide hypersensitivity (it is a sulfonamide derivative). Adrenocortical insufficiency. Known hypersensitivity.

Species-specific warnings

Horses: For HYPP, dose to prevent attacks and combine with dietary potassium restriction; note it is a prohibited substance in many competitions (medication rules).

Adverse effects

• Metabolic acidosis (self-limiting), hypokalaemia
• GI upset, inappetence
• Polyuria (weak/transient diuresis)
• Lethargy, paraesthesia-type signs; sulfonamide effects (rare)

Drug interactions

• Other potassium-losing diuretics/corticosteroids: additive hypokalaemia
• Drugs whose excretion depends on urine pH (e.g. salicylates): altered by urinary alkalinisation
• Digoxin: hypokalaemia increases toxicity
• Other carbonic anhydrase inhibitors (topical): additive

Pregnancy and lactation

Teratogenic in some lab studies — avoid in pregnancy unless clearly needed.

Monitoring

• Electrolytes (especially potassium) and acid–base status
• Intra-ocular pressure (glaucoma) or attack frequency (HYPP)
• Renal/hepatic function; hydration
• Sulfonamide idiosyncrasies on prolonged use

Toxicity and overdose

Overdose causes marked metabolic acidosis, hypokalaemia, dehydration, lethargy and GI upset; can precipitate hepatic encephalopathy in liver disease. As a sulfonamide, rare idiosyncratic effects (blood dyscrasias, KCS) are possible. Its diuretic effect is self-limiting (acidosis curtails it).

Management: No specific antidote. Discontinue; correct acidosis and electrolytes (potassium), rehydrate; supportive care. Monitor acid–base and electrolytes until stable.

Clinical pearls

• A multi-use carbonic anhydrase inhibitor — short-term IOP reduction in glaucoma, a bicarbonate diuretic for metabolic alkalosis, and (key in horses) HYPP attack prevention
• For HYPP Quarter Horses, pair it with a low-potassium diet — it helps keep serum potassium stable
• Expect a self-limiting metabolic acidosis and potassium loss — monitor electrolytes/acid–base
• It is a sulfonamide and can precipitate hepatic encephalopathy in liver disease — use cautiously; topical CA inhibitors are preferred for chronic glaucoma

Mechanism of action

Inhibits carbonic anhydrase, the enzyme that catalyses CO2 + H2O ⇌ H2CO3. In the renal proximal tubule this reduces bicarbonate (and sodium/water) reabsorption → a self-limiting bicarbonate diuresis and metabolic acidosis with potassium loss. In the eye it reduces ciliary-body bicarbonate transport and aqueous humour formation, lowering intra-ocular pressure. In HYPP, the induced mild acidosis and renal potassium excretion help stabilise serum potassium and prevent depolarising attacks.

Formulations and products

• 250 mg tablet
• Injection 500 mg vial (reconstitute)
• Ophthalmic-relevant (systemic for glaucoma)
• Diamox / Iopar-SR — 250 mg tablet; 500 mg vial / SR capsule, Tablet / injection (human-label)

Storage

Tablets: 15–30 °C, dry. Injection: reconstitute per label, use promptly. Protect from light.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other diuretics

• Furosemide
• Hydrochlorothiazide
• Mannitol
• Spironolactone
• Torsemide (Torasemide)

Frequently asked questions