Permethrin: veterinary dose and monograph

At a glance

Drug class

Antiparasitic

Also known as

Permethrin, Vetmec (component), K9 Advantix (component)

Species with doses

Dogs, Cattle, Horses and Sheep

Routes

Topical

Last reviewed

1 October 2026

Indications

• Canine flea, TICK, mosquito, sand-fly and lice control / repellency (incl. leishmaniasis vector protection)
• Livestock ectoparasite control (flies, lice, ticks, mites) — sprays/pour-ons/dips
• Environmental/premises insect control

Permethrin 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

• Flea/tick/insect control & repellency (spot-on): Label-sourced — Plumb’s 10e p.1459 (Permethrin, Topical) gives no amount, only that products are typically applied every 2 or 4 weeks per the product label; Papich 5e has none. Apply the weight-band spot-on to the skin; gives tick and sand-fly repellency. NEVER use the dog product on cats, or on dogs living with cats that groom them. Wear gloves when applying.

Cats

• CONTRAINDICATED: Cats cannot glucuronidate permethrin; exposure to dog spot-ons (45–65%) — even by grooming a treated dog — causes tremors, seizures and death. Treat with bathing, methocarbamol and supportive care.

Cattle

• Fly/lice/tick control (pour-on/spray): Label-sourced — Plumb’s notes many livestock pour-on, spray and dust products; dose and withdrawal follow the product label.

Horses

• Fly/tick control (spray): Fly repellent sprays/wipes.

Sheep

• Lice / keds / blowfly (topical): Pyrethroid pour-on/dip for sheep ectoparasites; follow product concentration and withdrawal. (Cats are highly permethrin-sensitive — keep treated sheep away from cats.)

Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

• Fly/lice/tick control (pour-on/spray): Label-sourced — Plumb’s notes many livestock pour-on, spray and dust products; dose and withdrawal follow the product label.

Contraindications

CATS — concentrated/dog formulations are CONTRAINDICATED (fatal tremorgenic toxicosis); keep treated dogs separated from in-contact cats until dry. Fish/aquatic environments (highly toxic to fish and bees). Application to broken skin. Known hypersensitivity.

Species-specific warnings

Cats: FATAL — concentrated/dog permethrin products cause life-threatening tremors and seizures in cats. Never apply to cats; separate treated dogs from cats until dry. Treat exposure as an emergency (decontaminate + methocarbamol + IV lipid).

Adverse effects

• Dogs: transient application-site paraesthesia (scratching/rubbing), mild local reaction
• Cats (toxicosis): tremors, hyperthermia, seizures — often FATAL
• Hypersalivation if licked
• Environmental toxicity (fish, aquatic invertebrates, bees)

Drug interactions

• Other neurotoxic insecticides (organophosphates/carbamates): additive toxicity
• Often combined with imidacloprid (K9 Advantix) for added flea adulticide effect
• No major systemic therapeutic interactions (topical)

Pregnancy and lactation

Topical use in dogs/livestock is generally considered low-risk at label use; follow product label.

Monitoring

• Dogs: application-site reaction; flea/tick control efficacy
• Multi-pet homes: ensure cats cannot contact/groom treated dogs until dry
• Cats with exposure: neurologic status, temperature — treat as emergency
• Environmental stewardship (fish/bees)

Toxicity and overdose

In DOGS, well tolerated topically (transient paraesthesia). In CATS, permethrin causes a severe, frequently FATAL tremorgenic toxicosis — generalised tremors, hyperthermia, ataxia and seizures within hours — usually from a misapplied dog spot-on or from grooming a recently treated dog. Highly toxic to fish/aquatic life.

Management: Feline permethrin toxicosis is an EMERGENCY: decontaminate (bathe with liquid dish soap in lukewarm water to remove residual product), control tremors/seizures with METHOCARBAMOL (first-line) and/or benzodiazepines/barbiturates, INTRAVENOUS LIPID EMULSION for refractory cases, active cooling for hyperthermia, IV fluids and intensive supportive care. With aggressive treatment many cats survive.

Clinical pearls

• Excellent canine TICK and sand-fly/mosquito REPELLENT (valuable for leishmaniasis prevention) — often paired with imidacloprid
• THE classic fatal feline poisoning: never apply dog permethrin spot-ons to cats, and keep cats away from freshly treated dogs until dry
• Treat feline toxicosis aggressively — bathe to decontaminate, methocarbamol for tremors, IV lipid emulsion if refractory; prognosis is good with prompt care
• Highly toxic to fish/aquatic invertebrates and bees — dispose responsibly

Mechanism of action

A type-I pyrethroid that slows the closing of voltage-gated SODIUM channels in arthropod nerve membranes, causing repetitive depolarisation, hyperexcitation, paralysis and death of the insect/tick (plus a contact-irritant repellent effect). Insects are far more susceptible than mammals; cats, however, are uniquely sensitive because they poorly glucuronidate permethrin, allowing toxic accumulation and neurotoxicity.

Formulations and products

• Spot-on 45–65 % (concentrated, dogs)
• Spray / dip / pour-on (livestock, lower %)
• K9 Advantix (imidacloprid + permethrin) (Elanco (Bayer)) — Permethrin + imidacloprid spot-on, Topical spot-on
• Permethrin pour-on/spray (livestock) (Various) — Permethrin (various %), Pour-on / spray / dip
• Permethrin 5 % cream / 1 % lotion — 5 % cream (scabies); 1 % lotion (lice), Topical (human-label)

Storage

Spot-ons/sprays: 15–30 °C in original packaging; keep away from cats, children and water bodies (aquatic toxicity).

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 antiparasitics

• Nitenpyram
• Nitroxynil
• Oxfendazole
• Oxibendazole
• Piperazine
• Ponazuril
• Praziquantel
• Pyrantel pamoate

Frequently asked questions