How facial tremors change the emergency level
Facial muscle twitching confirms permethrin is already attacking your cat's nervous system—this isn't a "maybe" exposure. The tremors mean nerve cells are firing uncontrollably, and without rapid treatment, it will spread to larger muscle groups. Unlike toxins that cause lethargy first, permethrin's hallmark is hyperexcitability.
At 20 minutes post-grooming, the timeline is critical. Symptoms appearing this fast suggest significant exposure, likely from ingesting while licking the dog's treated fur. The spot-on's oily residue clings to paws and whiskers, so even if you didn't see her lick directly, grooming transfers concentrated amounts.
Immediate steps while waiting for the vet
Washing with dish soap (like Dawn) breaks down the oily permethrin residue better than water alone. Focus on her face, paws, and any damp patches where she may have groomed—but avoid stressing her further. If she's too agitated, prioritize getting her into the carrier; a seizure during bathing could lead to drowning.
Darkness matters more than you'd think. Permethrin-poisoned cats become hypersensitive to stimuli—a slamming door or flashlight can trigger seizures. If possible, move her to a dim bathroom (close curtains, turn off lights) while preparing to leave. Silence your phone; even ringtones can worsen tremors.
Why transport prep can't wait
With early neurological signs, your cat's condition could deteriorate mid-transit. Line the carrier with absorbent pads (or a towel you're willing to discard), as drooling and urinary incontinence often escalate. Bring the permethrin package—the concentration percentage guides the vet's treatment plan.
If she starts seizing en route, don't try to restrain her. Cover the carrier with a blanket to block external stimuli, and ensure the car interior is quiet (no radio, no loud conversations). Time any seizures; even brief ones require different treatment than continuous tremors.
The 4 kg factor in treatment urgency
Your cat's weight puts her at higher risk than larger cats—the same toxin dose circulates more intensely in her smaller bloodstream. Vets often administer lipid therapy intravenously, where body weight determines both the safe dosage and infusion speed.
Watch for "quiet" symptoms between tremors: dilated pupils that don't respond to light, or sudden vocalizations. These indicate deepening neurological impact. Don't offer food or water—nausea from the toxin combined with impaired swallowing could cause aspiration. Your vet will likely administer fluids via IV instead.
The step-by-step response, from the first minute to the vet visit, is in our Permethrin Toxicity in Cats emergency guide.