Mannitol
Mannitol expands plasma osmolality and promotes diuresis; it is used for selected cerebral or ocular pressure emergencies.
Group
Osmotic diuretic
Mechanism of Action
Filtered mannitol is poorly reabsorbed and retains renal tubular water; plasma osmotic effects draw fluid from tissues.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Osmotic diuresis | 1 g/kg | IV | Use a suitable 5-25% solution and reassess urine flow. | |
| Fluid expansion | 0.5–2 g/kg | IV | ||
| Fluid expansion | 0.1 g/kg/hour | IV | Continuous | |
| Acute glaucoma or cerebral oedema | 0.25–2 g/kg | IV | Every 6 h | 15-25% solution over 30-60 minutes; repeat only if needed after reassessment. |
| Oliguric renal failure trial | 0.25–0.5 g/kg | IV | Every 4–6 h | Do not use in: Anuria, Volume overload, Dehydration; Only after rehydration and confirmation of residual urine production; over 5-10 minutes, repeat only if a clear diuretic response occurs. |
| Diuresis induction — Loading | 0.5 g/kg | IV | Over 20-30 minutes; require a measurable diuretic response before continuing. | |
| Diuresis induction — Maintenance | 60–120 mg/kg/hour | IV | Continuous | Only if the loading dose produces significant urine output; reassess fluid balance. |
| Acute glaucoma | 0.5–1 g/kg | IV | Over 15-20 minutes; water-access restriction described in ocular protocols requires consideration of hydration. | |
| Acute glaucoma | 1–2 g/kg | IV | 20% solution over 20 minutes when initial local ocular treatment is inadequate. | |
| Cerebral oedema reassessed boluses | Reference only | IV | 0.5-1.5 g/kg over 10-20 minutes, with 6-8-hour repeats only when response supports them. One guideline limits exposure to three boluses per 24 hours; measure osmolality and electrolytes and avoid uncontrolled repeated dosing. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Fluid expansion — Loading | 0.5–0.8 g/kg | IV | Administer over 5 minutes with close volume-status monitoring. | |
| Fluid expansion — Maintenance | 1 mg/kg/min | IV | Continuous | |
| Oliguric renal failure trial | 0.25–0.5 g/kg | IV | Every 4–6 h | Do not use in: Anuria, Volume overload, Dehydration; Only after rehydration and confirmation of residual urine production; over 5-10 minutes, repeat only if a clear diuretic response occurs. |
| Diuresis induction — Loading | 0.5 g/kg | IV | Over 20-30 minutes; require a measurable diuretic response before continuing. | |
| Diuresis induction — Maintenance | 60–120 mg/kg/hour | IV | Continuous | Only if the loading dose produces significant urine output; reassess fluid balance. |
| Acute glaucoma | 0.5–1 g/kg | IV | Over 15-20 minutes; water-access restriction described in ocular protocols requires consideration of hydration. | |
| Acute glaucoma | 1–2 g/kg | IV | 20% solution over 20 minutes when initial local ocular treatment is inadequate. | |
| Cerebral oedema reassessed boluses | Reference only | IV | 0.5-1.5 g/kg over 10-20 minutes, with 6-8-hour repeats only when response supports them. One guideline limits exposure to three boluses per 24 hours; measure osmolality and electrolytes and avoid uncontrolled repeated dosing. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Neonatal osmotic therapy | 0.25–1 g/kg | IV | Foals: 20% solution over 15-20 minutes. | |
| Osmotic therapy | 0.25–2 g/kg | IV | 20% solution by slow IV administration. | |
| Traumatic intracranial hypertension | 0.25–1 g/kg | IV | As needed | Intermittent bolus with reassessment; avoid hypovolaemia and hypotension. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Cerebral oedema | 1–3 g/kg | IV | Historical adjunctive regimen; assess concurrent treatment and fluid/osmolality risk. | |
| Oliguric renal failure | 1–2 g/kg | IV | Do not use in: Anuria, Volume overload, Dehydration; Only after rehydration, with measured urine response and fluid balance. |
Pigs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Cerebral oedema | 1–3 g/kg | IV | Historical adjunctive regimen; assess concurrent treatment and fluid/osmolality risk. | |
| Oliguric renal failure | 1–2 g/kg | IV | Do not use in: Anuria, Volume overload, Dehydration; Only after rehydration, with measured urine response and fluid balance. |
Sheep
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Cerebral oedema | 1–3 g/kg | IV | Historical adjunctive regimen; assess concurrent treatment and fluid/osmolality risk. | |
| Oliguric renal failure | 1–2 g/kg | IV | Do not use in: Anuria, Volume overload, Dehydration; Only after rehydration, with measured urine response and fluid balance. |
Goats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Cerebral oedema | 1–3 g/kg | IV | Historical adjunctive regimen; assess concurrent treatment and fluid/osmolality risk. | |
| Oliguric renal failure | 1–2 g/kg | IV | Do not use in: Anuria, Volume overload, Dehydration; Only after rehydration, with measured urine response and fluid balance. |
Indications
- Cerebral oedema
- Acute glaucoma
- Selected osmotic diuresis
Contraindications
- Dehydration
- Use cautiously with suspected intracranial bleeding or limited cardiac reserve.
Interactions
- Avoid coadministration with blood products through the same system unless compatibility is established.
- May increase renal clearance of other drugs.
Adverse effects
- Fluid and electrolyte depletion
- Acute intravascular expansion and volume overload
Toxicity
Stop excess exposure and monitor fluid balance, osmolality, electrolytes and cardiovascular status.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Mannitol 5% injection | Injection | 5 g / 100 mL | IV |
| Mannitol 10% injection | Injection | 10 g / 100 mL | IV |
| Mannitol 15% injection | Injection | 15 g / 100 mL | IV |
| Mannitol 20% injection | Injection | 20 g / 100 mL | IV |
| Mannitol 25% injection | Injection | 25 g / 100 mL | IV |
Monitoring and Administration
Monitor hydration, urine production and electrolytes; measure intraocular pressure when treating glaucoma.
Inspect for crystals before administration; cold storage can promote crystallization. Use product-specific crystal-dissolution and filtration instructions.
Discard unused portions after a single-use container is opened.
The general large-animal osmotic-therapy instruction is 0.25-1 g/kg IV as 20% solution over 1 hour. It does not identify the species, so it is not assigned automatically to cattle or horses.
Inspect for crystals, warm and filter using the actual product instructions; one protocol uses a 5-micron in-line filter. Follow serum sodium, renal function, urine output, pulmonary signs and measured osmolality; 320 mOsm/L is a cited precautionary threshold rather than a guarantee of renal safety. Repeat boluses totalling up to 1.5 g/kg at 30-40-minute intervals require cumulative tracking. A trauma combination adds furosemide 1 mg/kg IV 20 minutes after mannitol 0.5-1 g/kg; avoid applying it to an unstable depleted patient.