Tick and Flea Medicine Poisoning in Cats


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Pyrethroid and Pyrethrin are insecticides which are commonly used for treating

tick and flea infestation in pets

. Pyrethrins are naturally derived from Chrysanthemum cinerariaefolium and other pyrethrum plant species. Pyrethroids, on the other hand, are synthetic and last longer. These include etofenprox, tetramethrin, phenothrin, permethrin, fluvalinate, fenvalerate, deltamethrin and cypermethrin.If your cat has an adverse reaction to any of these chemicals, it will affect its nervous system and reversibly prolongs the sodium conductance in the nerve axons, which will lead to repetitive discharges from the nerves. These types of reactions are more common in cats than they are in dogs because they are more sensitive. If your cat is old, young, debilitated or sick, these chemicals pose an even higher risk to their nervous system. The reactions will become worse if your cat is hypothermic.


Cats are particularly sensitive to pyrethroids. If your cat is treated with a product containing permethrin (which is labeled for uses only on dogs), they end up developing muscle tremors, seizures, incoordination, hyperthermia and eventually death within hours of the incipient toxicity. Products that contain phenothrin might lead to similar, but less severe reactions. Some of the most common symptoms associated with pyrethroid toxicity include:

  • Allergic reactions โ€“ congestion, hives, extreme sensitivity, itching, respiratory distress, shock and death.
  • Idiosyncratic reactions โ€“ These resemble toxic reactions at lower doses.
  • Mild reactions โ€“ Hyper salivation, ear twitching, paw flicking, diarrhea, vomiting and mild depression.
  • Medium to severe reactions โ€“ Protracted diarrhea and vomiting, incoordination, depression and muscle tremors (these must be differentiated from ear twitching and paw flicking).

As we mentioned earlier, cats are much more sensitive to insecticides than dogs. Their metabolic pathways are less efficient and they also have fastidious grooming habits. Their long coats also end up retaining a lot of topical products. Cats that have really low temperatures (after bathing, sedation or anesthesia) are also more predisposed to the clinical signs of toxicity.


Your vet will perform a thorough physical exam on the cat, and take into account the background history of all the symptoms and the possible incidents which might have led to the condition. You might have to let your vet know as to whether you cat was exposed to the aforementioned substances, and the quantity of the products that he might have been exposed to.If your cat has been around another animal that has been treated with these products, you will need to alert your vet. It would also be extremely helpful if you have a good idea of when the symptoms started becoming apparent. It is quite difficult to detect the insecticides in the fluids or the tissues of the cat. A thorough history is the best way to identify the chemical culprit.

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