The Animal Doctor by Dr. Michael W. Fox

Anti-Flea Treatments Sickening, Killing Companion Animals

DEAR DR. FOX: I have a 13-week-old puppy, and I used Activyl on him for fleas. About seven days later, he starting having these aggressive outbursts, then acts overly sweet after. You can almost see the confusion in his eyes.

This is not like him in any way. I don’t know if it’s the medicine, but that’s the only thing we have changed. Have you gotten any more reports on this? -- A.T., Tulsa, Oklahoma

DEAR A.T.: I am shocked you treated such a young dog with this kind of product. If a veterinarian prescribed this, he or she should go back to school. Most likely you made the purchase in a local store, which should be prohibited in every community and state.

Until your communication, I was not aware that indoxacarb -- the highly toxic, hazardous insecticide in Activyl -- was approved for companion animal use. It is strictly regulated in Europe: Greenpeace has put this chemical on its E.U. Pesticide Blacklist.

In addition to being toxic, this product does not kill the targeted insects before they have a chance to transmit any diseases they may be carrying. According to one report from the European Medicines Agency, “The most common side effects seen with Activyl Tick Plus (which may affect up to 1 in 10 animals) are transitory scratching, erythema (reddening of the skin) and hair loss at the application site. ... Activyl Tick Plus must not be used in cats as adverse reactions and even death can occur. ... Fleas, ticks and sand flies might still be able to transmit any diseases which they may be carrying.”

Various flea and tick insecticides have caused sudden, unprovoked aggression in dogs. There are safer alternatives to repelling fleas, ticks and other biting insects. All responsible, caring dog and cat owners should adopt these methods, rather than continuing to use insecticides that can cause seizures and death (as with Bravecto) year in and year out on their animals. Short- and long-term adverse health and environmental consequences can be avoided. For such preventive measures, see my website,


From Johnathan Hettinger, Midwest Center for Investigative Reporting, March 26:

“Two pet owners who claim their dogs either died or developed problems after using Seresto flea and tick collars filed a class-action lawsuit this week against Elanco Animal Health, alleging it misrepresented the safety of its product.

“The lawsuit, filed in the U.S. District Court of California in Los Angeles, comes just days after a congressional subcommittee asked Elanco to voluntarily recall the flea and tick collars in the wake of reporting by the Midwest Center for Investigative Reporting and USA TODAY on thousands of incident reports about pet and human harm linked to the collar. The lawsuit cites the news outlets’ reporting. Elanco declined to voluntarily recall the product.”

(Send all mail to or to Dr. Michael Fox in care of Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106. The volume of mail received prohibits personal replies, but questions and comments of general interest will be discussed in future columns.

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