Flea Product Reactions/Toxicity

Almost all of the flea product toxicity cases seen at MedVet are the result of owners failing to follow label directions. It is very important, especially in cats, that all label directions are read and followed. In particular, DO NOT use canine products, in any quantity, on cats. Also, puppies and kittens are more sensitive than adults and special products MUST be used when treating them.

The most common type of flea control products on the market are pyrethrum-based. The main ingredient may be listed as a pyrethrum, pyrethroid, or permethrin. These products are derived from the Chrysanthemum plant family and are safe and effective when used properly. Cats are more sensitive to the toxic effects of the pyrethrums than dogs and particular care should be taken when using these products on cats.

Pets can become sick if too much of a product is applied, if the wrong product is applied, or if the pet licks and ingests the product after application. The most common toxic effects are muscle tremor and excessive salivation. Signs of toxicity can occur from 1 to 12 hours after application. If any of these signs occur after applying a flea product, wash the pet with warm water and a mild detergent (e.g. Ivory/Joy dishwashing liquid) and call your veterinarian right away. Chilling can occur so dry the pet thoroughly after bathing and keep them warm. With prompt treatment, including IV fluids, muscle relaxants, and symptomatic care, most pets make a full recovery.

Some types of flea products may contain organophosphates. Brand names and active ingredients include: Dursban, Chlorpyrifos, Dichlorvos, Fenthion, Diazinon, Malathion, and Sevin. Again, cats are more sensitive than dogs to the toxic effects of organophosphates. Be very careful that the product being used is appropriate for the species, weight, and age of the pet. Common signs of organophosphate poisoning are diarrhea, vomiting, trouble breathing, small pupils, muscle tremor, weakness/falling over, and drooling. Organophosphate toxicity can be rapidly fatal depending on the agent and the dose that the pet is exposed to. Removing the product by washing the pet should be the first step if the product has been applied recently. You also need to immediately call to your veterinarian. There is a specific antidote to this type of poisoning, but it is only effective if given early. Pets that have been poisoned with an organophosphate almost always require IV fluids, supportive care, and hospitalization.

Some other general guidelines for flea products are:

• Do Not use more than one flea product on your pet at a time unless specifically directed by your veterinarian. Two safe products can be dangerous when used together.
• If several pets are treated with a topical product they should be separated so that they cannot lick the product from each other.
• Read label directions carefully and be sure that the product that you are using is appropriate for the species, age, and weight.
• Veterinary products are safer and more effective than over-the-counter products.
• Do not apply a topical flea product to skin that is red, irritated, or broken open.