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Mannitol for Pets: Diuretic for Edema, Glaucoma, Brain Swelling

Published on September 10, 2024
Updated on November 5, 2025
Reviewed by Petco's Veterinarian Team

Mannitol is an osmotic diuretic that removes excess fluid from the body.

Summary

Used For:

Removes excess fluid from the body decreasing swelling

Brands:

Osmitrol

Species:

All veterinary species

Other names:

Drug type:

Diuretic

Prescription required:

Yes

Pregnancy and lactation:

Safe use in pregnant or lactating animals has not been established.

Side effects:

Fluid loss and electrolyte imbalance.

General description

Mannitol acts as an osmotic diuretic to pull fluids from the body that have accumulated where they should not. Mannitol has a potent diuretic effect when compared to other diuretics and should be used cautiously to avoid excessive fluid loss.

Uses

Promotes diuresis (higher urine production) in acute oliguric kidney failure (no urine is being produced), to decrease pressure in the eyes (as in glaucoma) or on the brain, to increase the excretion of some toxins through the kidneys, or to rapidly reduce edema (swelling) or ascites.

How it works

Mannitol prevents fluids from being reabsorbed by the kidneys. It also prevents the reabsorption of sodium chloride and other solutes in the body. This combination of effects causes fluids to be lost from the body.

Dosage

Dogs: 1 gram per kilogram of body weight given intravenously when using the 5-25% solution.

Cats: 0.5 grams per kilogram to 0.8 grams per kilogram given intravenously over 5 minutes, then 1 gram per kilogram per minute given at a constant rate.

Forms

Mannitol is available in a 5%, 10%, 15%, 20% and 25% injectable solution.

Storage information & handling

Injectable mannitol should be stored at room temperature.

What results can I expect?

Mannitol begins working rapidly and diuresis should occur within 20-30 minutes.

Missed Dosage

If a dose is missed, another dose is often given immediately.

Overdose / acute toxicity

In an overdose, excessive excretion of sodium, potassium and chloride in the urine may cause fluid buildup in the lungs.

Side effects

May include:

  • Fluid loss (dehydration)
  • Electrolyte imbalances (e.g., abnormally low or high levels of potassium, sodium or calcium in the blood)
  • Nausea
  • Vomiting
  • Pulmonary edema
  • Dizziness
  • Headache
  • Heart disorders

Contraindications

*Do not use in animals requiring prompt intestinal evacuation.

*Do not use in animals that have fecal impaction or intestinal obstruction.

*Free access to fresh water is necessary.

*Discontinue use and contact a veterinarian if vomiting occurs.

*Do not use in patients with anuria (inability to produce urine) due to kidney disease.

*Do not use in patients who suffer from severe dehydration, bleeding in the brain or certain lung diseases.

*The patient must have some kidney function with urine output for this drug to work and to be used.

Drug interactions

Mannitol may increase the kidney excretion of lithium.

Use of mannitol concurrently with blood products requires certain precautions to prevent agglutination of the blood.

Precaution

Close monitoring is essential.

Sources

Saunders Handbook of Veterinary Drugs

VIN Veterinary Drug Handbook

Disclaimer
The information contained on this page is for educational purposes only. This medication should only be given under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.

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