Pets story oversimplifies pyrethrins.

Health effects of the commonly used, plant-derived insecticides, called pyrethrins, have been the subject of recent scientific study. So a March 18 story by two reporters from NBC Los Angeles takes an important step in investigating how safe pyrethrin-based flea and tick products are for dogs and cats.

The products are applied directly to the animals and can be eaten by them as they groom. Symptoms of pyrethrin poisoning include tremors, convulsions and even death.

But, the issue of the safety of pyrethrins is not as clear-cut as the news report makes it seem.

The reporters were diligent: they interviewed people whose pets died and they read reports from the Environmental Protection Agency’s (EPA) database of harmful incidents that followed pyrethrin use.

However, they fell short by not explaining that improper use and incomplete reports muddy the picture of how commonly pyrethrins cause serious harm in pets. Careful interpretation of owner's actions and the EPA's reports are needed.

For instance, were the products used according to directions? Some of the pyrethrins that are only for dogs are too strong for cats and can result in severe muscle twitching or death when put on cats. Yet this is a different situation than a cat product harming a cat.

Another important issue is if steps were taken to prove the insecticide caused harm. Although it is often impossible to prove or disprove the role of the product, diagnostic testing and the pet’s response to treatment should ideally be considered with each EPA report.

The reporters did not mention nuances such as these, leaving the impression that the problem of pyrethrin poisoning in pets is clear-cut.

They were on the right track, though, to interview a veterinarian, although selecting a celebrity veterinarian with ties to Bayer -- a company that makes competitive products -- may not have been the best choice. Regardless of Dr. Jeff Werber’s professional capabilities, his impartiality should be questioned given that he has been a spokesperson for Bayer Animal Health since 1998, as stated on his website. A better choice would have been to interview a veterinary toxicologist -- an animal doctor with advanced training in the effects of poisons -- that could have offered more thorough, perhaps less biased, insights into the complexities of the topics examined in this story.

This news story is an important first step that will hopefully lead to closer scrutiny of the safety of pyrethrins in animals, but the issue is far more complex than it seems at first glance.