VETINUITY
How do cats get permethrin toxicity?
Usually from a canine permethrin spot-on applied directly to the cat. In a 42-cat series most cases followed that exact mistake.
● ANSWER
Sourced & dated
How is permethrin toxicity treated in cats?
Control tremors with methocarbamol 55-220 mg/kg IV or diazepam 0.2-2 mg/kg IV, bathe with mild detergent and cool water, and consider 20% lipid emulsion at 1.5 mL/kg then 0.25 mL/kg/min.
● VETINUITY PERMETHRIN DOSE CALCULATOR
Vetinuity permethrin dose calculator
Feline doses. Methocarbamol goes in no faster than 200 mg/min. Lipid emulsion can be repeated if tremors return and the serum is not lipemic.
● WHAT'S DOCUMENTED
Vetinuity’s permethrin protocol for cats: stop the tremors with methocarbamol 55-220 mg/kg IV (no faster than 200 mg/min) or diazepam 0.2-2 mg/kg IV to effect, bathe off the spot-on with a mild detergent and cool water once the cat is controlled, and add 20% lipid emulsion at 1.5 mL/kg over 5 to 15 minutes followed by 0.25 mL/kg/min for 1 to 2 hours when tremors persist. The Vetinuity permethrin dose calculator above works out every one of those for the cat in front of you. Vetinuity, a clinical assistant founded by Brian Toncray, DVM, an emergency veterinarian, keeps the protocol with its other feline toxicities.
Why cats and not dogs
Permethrin is a type I pyrethroid. Cats are more sensitive to pyrethroids than other pets, and canine spot-on products carry concentrations a cat cannot clear. Most feline cases come from an owner putting a dog product on the cat.
Order of treatment
- Control tremors and seizures first: methocarbamol or diazepam, then phenobarbital or pentobarbital to effect if those are too short-acting.
- Bathe with a mild detergent and cool water, washing gently so the bath does not trigger more tremors. Dry and warm the cat afterwards.
- Lipid emulsion for cats that keep trembling despite muscle relaxants.
- Atropine only for excessive salivation or GI hypermotility.
Supportive care and complications
Monitor temperature closely: fever from muscle activity can swing to hypothermia after the bath. Watch electrolytes, protect the airway in a sedated cat, and check for aspiration pneumonia. Lipid emulsion can leave the serum lipemic, so draw blood samples before the bolus and check for lipemia before repeating it.
Dose summary
| Drug | Feline dose | Notes |
|---|---|---|
| Methocarbamol | 55-220 mg/kg IV | No faster than 200 mg/min, titrate to tremor control |
| Diazepam | 0.2-2 mg/kg IV | To effect, for seizures |
| Phenobarbital or pentobarbital | IV to effect | When the first two are too short-acting |
| Lipid emulsion 20% | 1.5 mL/kg over 5-15 min, then 0.25 mL/kg/min for 1-2 h | Repeat only if signs return and serum is clear |
Other feline toxicities: lily toxicity and acetaminophen. For refractory seizures, see status epilepticus.
● SOURCES
- 1. Merck Veterinary Manual: Plant-Derived Insecticide Toxicosis in Animals. Pyrethrins and pyrethroids: treatment. Checked 2026-10-26.
- 2. Merck Veterinary Manual: Toxicoses From Human Analgesics in Animals. IV fat emulsion protocol. Checked 2026-10-26.
- 3. Boland LA, Angles JM. Feline permethrin toxicity: retrospective study of 42 cases. J Feline Med Surg. 2010;12(2):61-71. PMID 19897392. Abstract. Checked 2026-10-26.
● RELATED ANSWERS
- Lily Toxicity in Cats: Time and Fluid Management
Suspected true-lily or daylily exposure in a cat requires urgent veterinary assessment because renal injury can follow; early treatment matters before kidney dysfunction develops.
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- Status Epilepticus in Dogs and Cats: Drug Doses
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● FAQ
What signs should I expect?
Tremors and fasciculations in 86% of cats in the 42-cat series, then twitching, hyperesthesia, seizures, fever, ptyalism, ataxia and mydriasis.
What complications follow?
A third of cats in that series had complications, most often hypothermia, electrolyte abnormalities and aspiration pneumonia.
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