Rockville, MD – "Severe illness and fatalities can occur in cats when their owners apply flea products intended for use on dogs only," said E. Kathryn Meyer, VMD, coordinator of the U.S. Pharmacopeia (USP) Veterinary Practitioners’ Reporting (VPR) Program. The VPR Program identifies product quality problems, medication mishaps, and adverse reactions with drugs, pesticides, chemicals, and biologics used in veterinary medicine. Most recently, USP’s VPR Program published a report on this important issue for pet owners in the July 15 issue of the Journal of the American Veterinary Medical Association (JAVMA).
Given that fleas are a warm weather problem, this is a timely warning for America’s 28 million cat owners. They need to know that, although many flea products are packaged very similarly, the active ingredients can vary greatly. For example, "spot-on" flea and tick products are popular alternatives to the traditional flea sprays, dips, powders, and shampoos. A small amount of liquid is applied directly to the animal's skin, often behind the neck or along the spine, usually on a once-a-month basis. Although some "spot-on" products have been approved for use in both dogs and cats, products containing concentrated permethrin (45% to 65%) are approved for use in dogs only and can be highly toxic to cats. In contrast, flea sprays intended for cats contain lower concentrations of permethrin (e.g., 2%) and are generally well tolerated.
"It is critical for owners to be aware of the severe consequences of using flea products incorrectly—particularly when cats are involved—because cats can be very sensitive to certain chemicals," continued Dr. Meyer. "Cat owners should read labels carefully before purchasing any flea or tick products. The products are considered safe when used properly; however, if owners do not follow the directions, severe harm to their pets can occur. For example, if a product label states that it should be used only for dogs, the product should never be used on cats, even in small amounts. Furthermore, people who own both dogs and cats should be aware that "dog-only" flea products applied to their dogs can cause illness in cats that are in close contact with the treated dogs."
As documented in the July 15 issue of the JAVMA, the USP VPR Program received 11 reports between August 1997 and September 1998, involving 12 cats that required hospitalization following exposure to a concentrated permethrin "spot-on" flea product. Despite hospitalization, four of the cats did not survive. Additionally, secondary exposure to permethrin can occur when cats are in close, physical contact with dogs treated with the chemical. The VPR Program received one report involving a cat that became ill simply through contact with two household dogs treated with a "spot-on" permethrin product.
In addition to reports received by USP, the JAVMA article reviewed cases reported to the Environmental Protection Agency (EPA). The EPA received reports involving 125 cats that became ill or died following incorrect direct application of permethrin and 24 cats that were sickened or died due to contact with permethrin-treated dogs in their households.
Concentrated permethrin "spot-on" products for dogs are available under a variety of different brand names in retail establishments (e.g., grocery stores, pet stores, department stores, hardware stores, etc.) and through mail-order pet supply catalogs. All products include a label warning that they are for use on dogs only, and should not be used on cats. Some labels even suggest separating household cats from treated dogs; however, the length of time the animals should be separated is not specified.
Unfortunately, in several cases reported through the VPR Program, the owners admitted that they saw the warning against use in cats, but thought a "small amount" would not be harmful. It is essential for pet owners to know that even a few drops can result in severe illness or death to one’s cat.
"Labeling changes designed to educate consumers may help reduce the incorrect use of permethrin products by pet owners," said Dr. Meyer. "These changes could include stronger warnings against the use on cats—with a description of the potentially fatal consequences of exposure—and explicit directions on how to prevent secondary exposure to cats when the product is used on dogs."
Signs of permethrin toxicity in cats often include excitability, twitching, and seizures. Quickly bathing the cat in a mild dishwashing detergent and seeking veterinary care will maximize the cat's chance of survival. Prevention, however, is a far simpler task. Pet owners should carefully read and heed all label information on pesticides before purchasing and applying to pets.
The following few simple tips can help keep cats healthy while treating them for fleas:
Do’s and Don’ts of Feline Flea Protection