# Acetazolamide: veterinary dose and monograph

> Acetazolamide is a veterinary diuretic. A carbonic anhydrase inhibitor with several niche uses: reducing intra-ocular pressure in GLAUCOMA (it cuts aqueous humour production), a weak diuretic that produces a bicarbonate diuresis (useful for metabolic ALKALOSIS), and… Indications include glaucoma — reduce intra-ocular pressure (aqueous humour suppression); hyperkalaemic periodic paralysis (HYPP) in horses — prevention of attacks; metabolic alkalosis (bicarbonate diuresis). This monograph lists 4 reference doses for dogs, cats and horses, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/acetazolamide · Last reviewed: 2026-10-01

## 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

*Acetazolamide doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Glaucoma / metabolic alkalosis | 4–10 mg/kg | PO | q8–12h | — |
| Hydrocephalus (paediatric, adjunct) | 0.1 mg/kg | PO | q8h | — |

- 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

*Acetazolamide doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Glaucoma (adjunct) | 7 mg/kg | PO | q8h | — |

- 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

*Acetazolamide doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Hyperkalaemic periodic paralysis (HYPP) | 2.2–4.4 mg/kg | PO | q8–12h | — |

- 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

> **Caution:** 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

> **Caution:** 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](https://vetmasterji.com/drugs/furosemide)
- [Hydrochlorothiazide](https://vetmasterji.com/drugs/hydrochlorothiazide)
- [Mannitol](https://vetmasterji.com/drugs/mannitol)
- [Spironolactone](https://vetmasterji.com/drugs/spironolactone)
- [Torsemide (Torasemide)](https://vetmasterji.com/drugs/torsemide)

## Frequently asked questions

### What is the dose of Acetazolamide for dogs?

Reference doses for Acetazolamide in dogs: 4–10 mg/kg PO q8–12h (Glaucoma / metabolic alkalosis); 0.1 mg/kg PO q8h (Hydrocephalus (paediatric, adjunct)). Confirm against the label and the patient before use.

### What is the dose of Acetazolamide for cats?

Reference doses for Acetazolamide in cats: 7 mg/kg PO q8h (Glaucoma (adjunct)). Confirm against the label and the patient before use.

### What is the dose of Acetazolamide for horses?

Reference doses for Acetazolamide in horses: 2.2–4.4 mg/kg PO q8–12h (Hyperkalaemic periodic paralysis (HYPP)). Confirm against the label and the patient before use.

### When should Acetazolamide not be used?

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.

### What are the side effects of Acetazolamide in animals?

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

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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