Pyrethrin/Permethrin Toxicity in Cats

Presentation & Diagnosis

Megan is a spayed female Domestic Shorthair cat that was presented at Iowa Veterinary Specialties for tremoring and was immediately triaged. On arrival, the owners had informed staff that Megan was accidentally washed in dog flea and tick medication. This type of medication contains pyrethrin which is extremely toxic to cats. Cats who are exposed to this type of medication can experience drooling, tremors, vomiting, diarrhea, restlessness, incoordination, disorientation, vocalization, skin twitches, muscle spasms, seizures, depression, and even death. Megan was diagnosed, hospitalized, and treated for pyrethrin toxicity.

About Pyrethrin

Pyrethrin is a neurotoxin derived from Chrysanthemum plants and kills fleas, ticks, and other insecticides. A synthetic form of Pyrethrin, Permethrin/Pyrethroids, is used in many pesticide products because it has been modified to last longer. Cats are much more susceptible to the effects of pyrethrin than dogs, due to the fact their liver is inefficient at glucuronide conjugation. This causes an accumulation of phase I metabolites that are extremely potent and slow down the breakdown of the pyrethrin compound, leading to toxicity. Pyrethrin and its derivatives exert neurotoxic effects on the central and peripheral nervous system. This is done through binding to sodium-gated voltage channels and decreasing the ability to inactivate them, thus resulting in hyperexcitability. This is crucial to know because most dog insecticide products contain a large amount of pyrethrin and its derivatives, whereas cat insecticides contain very little to none. When cats are treated with dog pesticides, adverse effects are typically seen.

Treatment

To stabilize Megan’s presenting condition, she was immediately bathed with dawn dish soap to help remove excess medication on the skin and fur. An IV catheter was placed and 4ml of propofol was titrated and administered IV to help minimize her pain. After treatment for Megan’s condition was approved by owners, she received 55mg/kg of methocarbamol IV slowly for her muscle tremoring. The team also started active warming due to her temperature being 90.5 degrees F. The patient’s blood glucose was initially 32 and was showing signs of respiratory distress. To treat her hypoglycemia, she was given 1ml/kg dextrose diluted to a 1:4 ratio with sterile water and administered IV over 1 minute. Megan was then given a second dose of methocarbamol and started intralipid emulsion (ILE) therapy at a bolus of 1.5 ml/kg, followed by 0.25 ml/kg/min for 60 minutes.

After stabilization, Megan was kept at IVS for close monitoring. She was started on IV fluids of Phylyte, Sodium Chloride solution, for 16ml/hr. As Megan’s condition progressively got worse, she was experiencing increased respiration effort and was placed in an Oxygen Snyder and supplemented oxygen at a rate of 7L/min, set on 65% humidity, and heated to help her hypothermia. Oxygen supplementation was paramount after she had been tremoring for a long duration of time, and her muscles, organs, and body had been depleted of oxygen. Technicians and doctors continued respiratory, heart rate, and temperature monitoring hourly. Megan was started on Amoxicillin/Clavulanic Acid, a penicillin antibiotic to treat infections, due to the radiograph findings of bronchopneumonia.

About 5 hours later, Megan’s vitals were normal and glucose levels were increased to 100 and eventually elevated within the normal range at 147. The owners opted to take Megan home after her improvement and were prescribed pradofloxacin, an antimicrobial medication used to treat skin, urinary tract, and respiratory infections in cats.

Diagnostics

During her stay, 3-view thoracic radiographs were taken that found an alveolar infiltrate in the right middle lung lobe that would be consistent with bronchopneumonia and was believed to be the cause of the respiratory clinical signs. There were also etiologies of pulmonary hemorrhage secondary to coagulopathy or pulmonary contusion secondary to trauma that should be considered.

A complete blood cell count was taken and the only significant finding from the testing was that there was a low amount of eosinophils, which is indicative of acute infections. The blood smear exhibited Dacrocytes seen in rare cases of toxins, Acanthocytes indicative of liver, splenic, or renal disease, and anisocytosis. The plasma of Megan’s blood was also lipemic, meaning there was a large presence of lipoproteins in her blood.

Intralipid Emulsion Therapy (ILE)

Permethrins are highly lipophilic molecules and have been found to respond very well to ILE therapy. ILE therapy works to expand the lipid compartment in the bloodstream to seclude the fat-soluble toxins and prevent them from reaching targeted organs and instead get excreted out of the body. In Megan’s case, she responded extremely well to the ILE therapy and showed remarkable signs of improvement after the treatment began.

Prognosis

Considering the duration of time that Megan was experiencing tremors, respiratory distress, and hypoglycemia, her prognosis was guarded to poor. There is no specific antidote to pyrethrin toxicity, therefore critical care and treatment is focused on the decontamination of the toxins and management of the clinical signs. With proper and immediate medical attention, pyrethrin toxicity can be treated and has a good prognosis. Prognosis decreases without treatment depending on organ function and neurologic activity. Each patient can present with different clinical signs, and it is important to manage those specific clinical signs causing there to be no structured and definitive treatment protocol. For example, if a patient was presenting with seizures, the treatment plan would have to focus on controlling and managing potential seizures.

Considerations

Cat owners should be aware of the dangers of pyrethrin toxicity as many flea/tick insecticides are advertised as being beneficial for both canines and felines when that is not the case. Cat owners must be aware of flea/tick medications, collars, shampoos, etc. that are made with pyrethrin, and/or its derivatives, to prevent cases of toxicity from occurring. It is always suggested to consult and confirm with their veterinarian for the safest and most effective option for flea/tick prevention and treatment.