In the context of the veterinary drug monitoring plan that ANSES has implemented via the French Agency for Veterinary Medicinal Products, serious and even lethal adverse reactions in cats treated with topical antiparasitic treatments containing permethrin used for treating dogs are regularly reported. ANSES therefore reminds cat owners to never use permethrin-based veterinary medicinal products on their cats and provides them here with a series of recommendations in order to avoid cat poisonings.
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Updated on 15/05/2019
No permethrin for cats
Permethrin-based dog antiparasitics are toxic for cats
ANSES's veterinary drug monitoring plan
Veterinary drugs only receive marketing authorisation if assessment of the data concerning their quality, safety and efficacy make it possible to conclude that the benefits linked to their use are greater than the risks incurred. The clinical trials conducted in the framework of a marketing authorisation application make it possible to highlight a certain number of adverse effects which may occur when using a given product. However, these trials are conducted on a limited number of animals and under standardised conditions of use. The large-scale use of a medicinal product under real-life conditions makes it possible to precisely pinpoint a product's adverse effects and to identify any potential risk factors (species, breed, age, pre-existing conditions, etc.). The veterinary drug monitoring plan implemented by ANSES via the French Agency for Veterinary Medicinal Products therefore aims to detect all emerging signs as quickly as possible, both unexpected adverse effects and known adverse effects demonstrating unexpected frequency or severity. This monitoring system provides adjustments to the risk management measures, which can span from the printing of additional precautions for use on the package leaflet, all the way to the withdrawal of marketing authorisation.
Permethrin is toxic for cats
In the context of this drug monitoring plan, ANSES regularly receives reports of serious and even lethal adverse reactions in cats treated with topical antiparasitic products containing permethrin, even though they are intended for dogs. These medicinal products can cause serious neurological disorders (trembling, convulsions, ataxia, agitation, coma) sometimes in conjunction with digestive symptoms such as hypersalivation, which can be fatal in cats. This toxicity is due to the cat's inability to eliminate certain compounds such as permethrin. Just a few drops from an eyedropper can be enough to cause severe effects in the most sensitive cats. Thanks to information campaigns implemented by the Agency since 2006 and targeting veterinarians and pet owners, as well as labelling changes on the products which highlight the fact that they are strongly counter-indicated for use on cats, there has been a sharp drop in the number of poisonings since 2007. But more work is still needed since in 2012 ANSES received another 258 declarations of adverse effects in cats due to permethrin-based treatment administration. 121 of the cases were considered serious and in 16 of the cases the animal died.
How to avoid accidents?
In this context, the Agency reminds cat owners to remain vigilant and not to treat their pets with medications containing permethrin.
In the event of accidental exposure to permethrin, if adverse effects are observed the cat should be washed with shampoo or soap and the advice of a veterinary practitioner should immediately be sought.
To prevent cats from accidentally being exposed to permethrin in homes where dogs and cats cohabit, dogs treated with permethrin should be kept separate from cats until the application of the antiparasitic treatment on the dog's body has dried, and cats should be prevented from licking the application areas on the treated dog.
Rare cases have also been reported after use of certain antiparasitic products for dogs (especially those in spray format) for the treatment of cat bedding and cushions. This treatment method should therefore be avoided.