# Mannitol: veterinary dose and monograph

> Mannitol is a veterinary diuretic. Osmotic diuretic — filtered freely by glomerulus, not reabsorbed → osmotic water retention in tubular lumen → diuresis. Indications include cerebral oedema — head trauma, neoplasia, post-CPR neuroprotection; acute glaucoma — emergency IOP reduction; oliguric acute kidney injury (after volume correction). This monograph lists 10 reference doses for dogs, cats, cattle, horses, goats and sheep and 1 more species, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

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

## At a glance

- **Drug class:** Diuretic
- **Also known as:** Osmitrol
- **Species with doses:** Dogs, Cats, Cattle, Horses, Goats, Sheep and Pigs
- **General dose range:** 250–2000 mg/kg IV q4–6h or CRI — check the species tables for the indication
- **Routes:** IV
- **Last reviewed:** 1 October 2026

## Indications

- Cerebral oedema — head trauma, neoplasia, post-CPR neuroprotection
- Acute glaucoma — emergency IOP reduction
- Oliguric acute kidney injury (after volume correction)
- Prevention of contrast-induced nephropathy
- Equine post-induction hypoxic encephalopathy

## Mannitol 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

*Mannitol doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Oliguric renal failure (after correcting volume) | 250–500 mg/kg | IV | over 5–10 min, repeat q4–6h or CRI | — |
| Cerebral oedema (head trauma) | 250–1500 mg/kg | IV | over 10–20 min; repeat q6–8h | — |
| Acute glaucoma — emergency IOP reduction | 500–2000 mg/kg | IV | over 20 min | — |

- Oliguric renal failure (after correcting volume): Plumb's: 0.25–0.5 g/kg IV over 5–10 min. If substantial diuresis, repeat q4–6h or give as CRI 8–10 % solution over 12–24 h.
- Cerebral oedema (head trauma): Plumb’s p.753: 0.5–1.5 g/kg IV over 10–20 min, repeat every 6–8 h by response (McDonnell 2004; Dewey 2008); 0.25 g/kg is as effective at lowering ICP but shorter-lived (Platt 2008). Papich 5e: 0.25–2 g/kg over 30–60 min. Limit to about 3 boluses per 24 h; keep osmolality ≤320 mOsm/L; do not use in hypovolaemia. Warm and filter to dissolve crystals.
- Acute glaucoma — emergency IOP reduction: Plumb’s p.753: 0.5–1 g/kg IV over 15–20 min (Wilkie 2002); 1–2 g/kg of 20% over 20 min (Millichamp 2006); 1 g/kg, may repeat in 4 h (Miller 2009). Withhold water for 1–4 h. Warm and filter the solution. Refer to ophthalmology.

### Cats

*Mannitol doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Cerebral oedema / acute glaucoma | 250–1500 mg/kg | IV | over 10–20 min | — |

- Cerebral oedema / acute glaucoma: Plumb’s p.753 gives dogs and cats the same doses: cerebral oedema 0.5–1.5 g/kg IV over 10–20 min (0.25 g/kg also effective); glaucoma 0.5–2 g/kg over 15–20 min. Cats are prone to volume overload — monitor closely.

### Cattle

*Mannitol doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Cerebral oedema (PEM, polioencephalomalacia) | 250–1000 mg/kg | IV | q4–6h until response | — | no slaughter withdrawal |

- Cerebral oedema (PEM, polioencephalomalacia): Papich 5e (large animals): 0.25–1 g/kg of 20% IV over 1 h. Plumb’s p.753 (Dill 1986): cattle, swine, sheep and goats 1–3 g/kg IV, usually with steroids and/or DMSO. Treat PEM primarily with thiamine.

### Horses

*Mannitol doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Cerebral oedema / raised ICP (foals and adults) | 250–1000 mg/kg | IV | bolus; repeat as needed | — |
| Oliguric renal failure | 250–500 mg/kg | IV | once, repeat in 4 h if response | — |

- Cerebral oedema / raised ICP (foals and adults): Papich 5e: 0.25–1 g/kg of 20% IV over 1 h; foals 0.25–1 g/kg over 15–20 min. Plumb’s p.753: traumatic brain injury — intermittent IV boluses of 0.25–1 g/kg; general range 0.25–2 g/kg by slow IV infusion (Schultz 1986).
- Oliguric renal failure: After volume correction only. Papich 5e: 0.25–1 g/kg of 20% IV over 1 h. Plumb’s p.753: 0.25–2 g/kg by slow IV infusion. Confirm a diuretic response before repeating.

### Goats

*Mannitol doses for goats*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Cerebral oedema (PEM in goats) | 250–1000 mg/kg | IV | q4–6h | — | no slaughter withdrawal |

- Cerebral oedema (PEM in goats): Papich 5e (large animals): 0.25–1 g/kg of 20% IV over 1 h. Plumb’s p.753 (Dill 1986): cattle, swine, sheep and goats 1–3 g/kg IV. Treat PEM primarily with thiamine.

### Sheep

*Mannitol doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Cerebral oedema (PEM in sheep) | 250–1000 mg/kg | IV | q4–6h | — | no slaughter withdrawal |

- Cerebral oedema (PEM in sheep): Papich 5e (large animals): 0.25–1 g/kg of 20% IV over 1 h. Plumb’s p.753 (Dill 1986): cattle, swine, sheep and goats 1–3 g/kg IV. Treat PEM primarily with thiamine.

### Pigs

*Mannitol doses for pigs*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Cerebral oedema / oliguric AKI | 250–1000 mg/kg | IV | q4–6h | — | no slaughter withdrawal |

- Cerebral oedema / oliguric AKI: Papich 5e (large animals): 0.25–1 g/kg IV over 1 h. Plumb’s p.753: cerebral oedema 1–3 g/kg IV (Dill 1986); oliguric renal failure 1–2 g/kg IV after rehydration (Osweiler 1986).

### Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

*Mannitol doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Cerebral oedema (PEM, polioencephalomalacia) | 250–1000 mg/kg | IV | q4–6h until response | — | no slaughter withdrawal |

- Cerebral oedema (PEM, polioencephalomalacia): Papich 5e (large animals): 0.25–1 g/kg of 20% IV over 1 h. Plumb’s p.753 (Dill 1986): cattle, swine, sheep and goats 1–3 g/kg IV, usually with steroids and/or DMSO. Treat PEM primarily with thiamine.

## Contraindications

Anuria (use cautiously — must verify patient CAN diurese before giving mannitol). Severe dehydration without IV fluid replacement first. CHF — additional fluid volume worsens pulmonary oedema. Active cranial haemorrhage with intact BBB — mannitol may worsen bleeding. Severe pulmonary oedema.

## Species-specific warnings

> **Caution:** Dogs: Head trauma: 1 g/kg IV over 15 min plus hyperventilation. Warm to body temp first.

> **Caution:** Cattle: PEM cerebral oedema — pair with thiamine 10 mg/kg IM q6h.

## Adverse effects

- Volume overload — pulmonary oedema, especially CHF patients
- Pulmonary oedema (with severe hypertension on the IV)
- Hyponatraemia / hyperkalaemia (dilutional)
- Acute renal failure if used in dehydrated patient
- Crystalluria (rare)

## Drug interactions

- Loop diuretics (furosemide): additive electrolyte loss — useful sometimes but monitor electrolytes carefully
- Cardiac glycosides (digoxin): mannitol-induced hypokalaemia potentiates digoxin toxicity
- Aminoglycosides: additive nephrotoxicity in dehydrated patients

## Pregnancy and lactation

Use only in life-threatening situations (cerebral oedema, AKI). Cross placenta minimally. FDA Category C.

## Monitoring

- Urine output (oliguric AKI primary endpoint)
- Electrolytes (Na, K, Cl) — baseline + 4 h post-dose, q6h if continuous
- Pulmonary status — auscultate lungs each dose
- Mental status — for cerebral oedema, look for improvement within 15–30 min
- Intra-ocular pressure (for glaucoma cases)

## Toxicity and overdose

Volume overload → pulmonary oedema (especially CHF, severe hypertension). Renal failure if used in dehydrated / anuric patient. Hyponatraemia (dilutional). Acute hyperkalaemia (potassium follows osmotic shift). Crystallisation in cold storage — warm to 30–37 °C and inspect before infusion.

Management: Stop infusion. Furosemide 1–2 mg/kg IV to offload volume. Treat hyponatraemia / hyperkalaemia per electrolyte protocol. Severe pulmonary oedema: oxygen, mechanical ventilation if needed.

## Clinical pearls

- Head trauma dog: 1 g/kg mannitol 20 % IV over 15 min produces ICP reduction within 15 min — hyperventilate to PaCO2 30–35 mmHg simultaneously
- Acute glaucoma cat / dog: 1 g/kg IV over 20 min is the emergency IOP-reduction tool until topical / surgical options take over
- PEM in goat / sheep / cow: thiamine 10 mg/kg IM q6h is the primary therapy; mannitol 0.5 g/kg IV adjunct for cerebral oedema
- Oliguric AKI dog: only give mannitol AFTER you have IV-fluid-restored volume; if no diuresis after 0.5 g/kg, do not repeat — switch to furosemide / dialysis
- Warm mannitol to body temperature before use — cold solution crystallises and infusing crystals is fatal
- NEVER mannitol in pulmonary oedema or severe CHF — additional fluid load is catastrophic

## Mechanism of action

Osmotic agent. Freely filtered at glomerulus, NOT reabsorbed → increases tubular fluid osmolality → water and electrolytes drawn into tubule → forced diuresis along entire nephron. In cerebral oedema: creates osmotic gradient across intact blood-brain barrier → water moves out of brain into vasculature → reduced intracranial pressure (effect within 10–15 min, peak 30–60 min). Similar mechanism in eye — vitreous water shifts to blood → reduced IOP.

## Formulations and products

- Mannitol 20 % IV solution (200 mg/mL)
- Mannitol 25 % IV solution (250 mg/mL)

## Storage

15–30 °C — DO NOT refrigerate (crystallisation). Warm to body temp before use; INSPECT for crystals — discard if present.

## 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

- [Acetazolamide](https://vetmasterji.com/drugs/acetazolamide)
- [Furosemide](https://vetmasterji.com/drugs/furosemide)
- [Hydrochlorothiazide](https://vetmasterji.com/drugs/hydrochlorothiazide)
- [Spironolactone](https://vetmasterji.com/drugs/spironolactone)
- [Torsemide (Torasemide)](https://vetmasterji.com/drugs/torsemide)

## Frequently asked questions

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

Reference doses for Mannitol in dogs: 250–500 mg/kg IV over 5–10 min, repeat q4–6h or CRI (Oliguric renal failure (after correcting volume)); 250–1500 mg/kg IV over 10–20 min; repeat q6–8h (Cerebral oedema (head trauma)); 500–2000 mg/kg IV over 20 min (Acute glaucoma — emergency IOP reduction). Confirm against the label and the patient before use.

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

Reference doses for Mannitol in cats: 250–1500 mg/kg IV over 10–20 min (Cerebral oedema / acute glaucoma). Confirm against the label and the patient before use.

### What is the dose of Mannitol for cattle?

Reference doses for Mannitol in cattle: 250–1000 mg/kg IV q4–6h until response (Cerebral oedema (PEM, polioencephalomalacia)). Confirm against the label and the patient before use.

### What is the withdrawal period for Mannitol?

Cattle, IV (Cerebral oedema (PEM, polioencephalomalacia)): no slaughter withdrawal; Goats, IV (Cerebral oedema (PEM in goats)): no slaughter withdrawal; Sheep, IV (Cerebral oedema (PEM in sheep)): no slaughter withdrawal; Pigs, IV (Cerebral oedema / oliguric AKI): no slaughter withdrawal. Follow the product label and national regulations where they differ.

### When should Mannitol not be used?

Anuria (use cautiously — must verify patient CAN diurese before giving mannitol). Severe dehydration without IV fluid replacement first. CHF — additional fluid volume worsens pulmonary oedema. Active cranial haemorrhage with intact BBB — mannitol may worsen bleeding. Severe pulmonary oedema.

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

Volume overload — pulmonary oedema, especially CHF patients; Pulmonary oedema (with severe hypertension on the IV); Hyponatraemia / hyperkalaemia (dilutional); Acute renal failure if used in dehydrated patient; Crystalluria (rare).

## Sources

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

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.