This study described 3 cases of feline permethrin toxicity treated with IV lipid emulsion (IVLE) as one component of therapy. All cases showed marked improvement of muscle tremors after IVLE administration. Feline permethrin toxicosis occurs most often when canine flea preventive is applied to a cat. Permethrin toxicity produces a prolonged opening of sodium channels causing tremors, ataxia, hyperesthesia, mydriasis, pyrexia, hypersalivation, vomiting, and seizures. Treatment usually includes controlling tremors, supportive care, decontamination, and promoting excretion.
IVLE, a new treatment for toxicities that are lipophilic (eg, permethrins), is a sterile, nonpyrogenic fat emulsion used in parenteral nutrition. The goal of IVLE in permethrin toxicity is to reduce permethrin tissue concentrations, thereby decreasing hospitalization time and mortality rates. The exact mechanism of action is unknown, but one theory suggests that an intralipid pulls lipophilic molecules out of the interstitium.
The recommended dose of 20% intralipid is a 1.5 mL/kg IV bolus over 30 minutes then 0.25 mL/kg/min IV over 30–60 minutes through a dedicated IV set. Additional doses can be administered after 6–8 hours if signs have not resolved and the serum is not grossly lipemic. IVLE should be used with conventional therapies for permethrin toxicosis, and owners should be advised of its off-label use.