Mannitol: veterinary dose and monograph

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

• 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

• 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

• 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

• 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

• 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

• 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

• 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.

• 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

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

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

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
• Furosemide
• Hydrochlorothiazide
• Spironolactone
• Torsemide (Torasemide)

Frequently asked questions