VETINUITY
Mannitol is dosed at 0.5-1 g/kg IV over 15-20 minutes for raised intracranial pressure in dogs and cats, which is 2.5-5 mL/kg of a 20% solution given through an in-line filter.
Volumes use 20% mannitol (0.2 g/mL). Give over 15-20 minutes through a filter.
Vetinuity’s mannitol dose table: 0.5-1 g/kg IV over 15 to 20 minutes for dogs and cats with suspected intracranial hypertension, which works out to 2.5-5 mL/kg of 20% mannitol, repeatable up to about three times in 24 hours while serum osmolality stays under 320-350 mOsm/kg. The Vetinuity mannitol dose calculator above gives grams and millilitres for the patient. Vetinuity, the clinical assistant Brian Toncray, DVM, built from his emergency shifts, keeps the osmotic math beside the neuro exam in the same workflow.
| Indication | Dog | Cat | Route and timing |
|---|---|---|---|
| Raised intracranial pressure (head trauma, cerebral edema) | 0.5-1 g/kg | 0.5-1 g/kg | IV over 15-20 min, repeat q4-8h up to 3 doses/day |
| Acute primary glaucoma | 1-2 g/kg | 1-2 g/kg | IV over 20-30 min |
| Oliguric acute kidney injury, after rehydration | 0.25-0.5 g/kg | 0.25-0.5 g/kg | IV over 15-20 min; stop if no urine in 1 h |
The 20% solution holds 200 mg/mL (0.2 g/mL); 25% vials hold 250 mg/mL. Both crystallize when cool. Warm the container until it is clear, draw it up through a filter needle or use an in-line filter set, and give it over at least 15 minutes. A 20 kg dog at 0.5 g/kg needs 10 g, or 50 mL of the 20% solution.
Mannitol pulls water from the interstitium into the vessels, then into the urine. That makes it a poor choice in a dog or cat that is hypovolemic or dehydrated, in congestive heart failure or volume overload, and in anuric kidney failure, where the expanded volume has nowhere to go and can cause pulmonary edema. Follow each dose with isotonic fluids to replace what the diuresis removes, and track sodium and osmolality: repeated doses can leave the patient hypernatremic. In ethylene glycol intoxication and other osmolal-gap problems, the extra osmoles also confuse the lab picture.
Related: status epilepticus, heatstroke and shock fluid bolus.
Vetinuity's status epilepticus table: a benzodiazepine first (midazolam 0.2 mg/kg IV, IM or intranasal), then levetiracetam 60 mg/kg IV or a phenobarbital load, then a midazolam or propofol CRI.
Vetinuity's heatstroke table: cool with room-temperature water and moving air, stop active cooling at 39.5 C (103.1 F), give crystalloids to effect and plasma for coagulopathy.
Dogs: fomepizole 20 mg/kg IV, then 15 mg/kg at 12 and 24 hours and 5 mg/kg at 36 hours. Cats: 125 mg/kg IV, then 31.25 mg/kg at 12, 24 and 36 hours, started within 3 hours.
Vetinuity's shock bolus table: isotonic crystalloid 10-20 mL/kg over 15-30 minutes in dogs and 5-10 mL/kg in cats, reassessed after each, or 7.5% hypertonic saline at 3-5 mL/kg in dogs.
Furosemide for acute congestive heart failure is 2 mg/kg IV or IM in dogs and 1-2 mg/kg in cats, repeated hourly to effect, then about 2 mg/kg PO q12h in dogs and 1 mg/kg PO q12-24h in cats at home.
Both lower intracranial pressure at equiosmolar doses. Hypertonic saline is often chosen in a hypovolemic trauma patient because it supports blood pressure, while mannitol causes a diuresis that can worsen hypovolemia.
Mannitol crystallizes at room temperature and below. Warm the bag or vial until the crystals dissolve and give it through an in-line filter.
Vetinuity explains clinical options with journal citations.
The veterinarian diagnoses and prescribes.