05/20/2014 05:14 pm ET Updated Jul 12, 2014

When It's Not Safe to Feed or Treat the Animals

This relates to two emails I recently received about products made and sold for our pets' well-being but which are proving to be anything but good for them.

The first email came from Carolyne Zinko, staff writer for the Sunday Style section of The San Francisco Chronicle. Her family decided to switch the flea meds they use for Fred, her family's 7 1/2-year-old beagle-mix, from Frontline to the housebrand sold by Costco. As she tells it, after two months of treatment:

"... he got out of his dog bed to go outside to the bathroom in our courtyard, where there are 3 steps he has to climb. He stumbled while getting out of his dog bed and had extreme difficulty using his hind legs. He limped down the 3 steps to the carport, tried to urinate and rolled over onto his back on the pavement, unable to walk. We had to go out and pick him up and carry him up the stairs. In the morning, he was trembling (not convulsing), a behavior or condition that continued for about a week (in the morning and at night) and had great difficulty getting out of his bed. He was able to walk a bit, but only on flat surfaces. He began refusing to walk up or down ANY stairs. We had to set up a shallow incline ramp to get him in and out of the house."

Trips to Fred's veterinarian proved inconclusive, but friends had seen similar problems with their dogs who'd been exposed to insect sprays in the backyard. That led to an Internet search where, writes Carolyne, "I found reports of cats dying from Costco flea medicine, and one post on Facebook from a man who said he had a dachshund who lost her ability to walk up and down stairs after using the Costco flea medicine. His other dog, using Frontline, was not impaired."

The key ingredient in the Costco product (manufactured by Kirkland) is Etofenprox. Etofenprox is not found in Frontline, Advantage, PetArmor, Zodiac, Advantix, or any but two of the several dozen other products I reviewed after hearing from Carolyne. Those two with Etofenprox as their active ingredient are Bio Spot and Vet-Kem, as well as of course the Costco brand.

Fred, happily, is fine. Again from Carolyne, "Once we stopped giving him the Costco medicine, it took several weeks and his demeanor changed completely. He has since returned to his frisky, feisty, combative, playful self. He leaps off the deck and runs up and down the stairs with no difficulty or hesitation."

Etofenprox is a synthetic pyrethrin, or a pyrethroid. While generally considered safe for use with dogs (much less so with cats, however), there are in fact quite a few articles to be found mentioning toxic reactions in both cats and dogs, most with remarkably similar symptoms. I find no articles reporting similar issues with products like Advantage and Frontline.

The Costco brand, it should also be noted, is manufactured in China. Quality control issues there are, of course, well documented and should be a real concern for anything any of us put in or on any of our or our pets' bodies.

Of equal concern, sent to me by another reader, a recent study documents that three U.S. pet food manufacturers' products contain aflatoxin B1, a notorious cancer-causing mold found on grains raised in inadequate conditions. The recent years' of drought have been linked to $75 million in insurance claims from growers of mold-infested corn. That surplus corn with a high level of the carcinogenic mold (corn considered unsafe for human consumption) is still permitted by the FDA for use in animal food.

The three manufacturers' products indicated in this are Purina, Hill's, and AvoDerm but it is not imagined that their products are the only ones which contain aflatoxin B1. Further, three brands (Purina, Iams, and Solid Gold) contained melamine or cyanuric acid, the chemicals indicated in thousands of pets poisonings back in 2007.