Used improperly, spot-on flea treatments can be dangerous to pets

A 5 on Your Side Investigation last fall found the potential dangers of popular spot-on flea and tick treatments.

Millions of pet owners use them, because they're easy and effective. But used improperly, they can cause cats and dogs to vomit, have seizures and in extreme cases, they might not survive.

"I thought I had poisoned him," said Sarah Biddle, of her normally playful cat, Uno.

Biddle says she followed the directions to apply an over-the-counter treatment, but she says within hours, Uno "was under the bed and howling and crying and meowing."

"I instantly knew that whatever I had done last night, or I had put on him, was making him sick," Biddle added.

5 on Your Side searched the Internet and found multiple posts showing animals with similar reactions – cats shaking and dogs with skin burns.

Dr. Diane Deresienski is a veterinarian at Bowman Animal Clinic in Raleigh. She says that she's never seen any complications firsthand but knows it can happen – typically when pet owners use the wrong product.

For example, they use dog products on cats and vice-versa. But the pesticides are not interchangeable, and they must be applied carefully, according to the directions.

"You want to try to apply it so that you get it down to the skin itself," Dr. Deresienski said.

On dogs, the recommended spot to apply the treatment is down the skin between the shoulder blades. For cats, she recommends the back of the head.

"Cats are pretty good at turning and licking things," Deresienski said. "So, if you get it up high enough they can't actually lick it off of them."

Be careful about how much you use.

Strictly follow the weight guidelines on the package so that you don't overdose. Make sure you apply the treatment every month, without fail.

Dr. Deresienski said that if you have young kids in the house, apply the treatment at night, so the kids won't accidentally touch the area before it dries.

As for Biddle's cat, Uno, he eventually recovered.

Deresienski's advice: Although spot-on flea and tick treatments help protect the pets and humans in your family, you have to be careful with how you use them.