5 On Your Side

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

Posted June 1, 2012

— Pet owners need to prepare.

Fleas and ticks could be a big problem this year, mainly because of the very mild winter. That means you need to protect your pets, but some common treatments can cause serious problems when they're not used correctly.

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.

Improper use of flea treatments can be dangerous Improper use of flea treatments can be dangerous

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.


This story is closed for comments.

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  • wmb95013 Jun 6, 2012

    i use the revolution product on my 3 cats and it works great!

  • cbwojcik5 Jun 5, 2012

    I have applied over the counter correctly on my two cats. On one cat, no problem, but the other cat gets lethargic, and her fur sticks up. My Vet said some cats are allergic to some meds just like humans. Plus there are no federal guidelines for pet meds.

  • southerntalent Jun 5, 2012

    the hartz and adams over the counter products includng flea collars are bad bad bad

  • Taffy Jun 4, 2012

    We had issues when we used Frontline on our cat. She would have seizures within days of being treated. Initially we had adopted her when friends moved & thought it was epilepsy. However I switched to Advantage & the seizures stopped & she never had another one after the switch. Had to be the Frontline. I've used spot on treatments for all my cats & dogs & this was the first time I had any reactions. I think animals can be allergic or sensitive to ingrediants just like people.

  • couldbeanyone Jun 4, 2012


  • couldbeanyone Jun 4, 2012

    we used the hartz stuff from walmart on our cat - she almost died. and we followed the directions exactly. the emergency vet said the stuff for cats contains a neurotoxin and many cats react to it. he had personally seen several people lose their cats to the over-the-counter stuff. our kitty was very sick but she survived. if you're going this route, don't be cheap - go to the VET and use their stuff! it's a different substance. and google hartz flea reactions to see just how many people have been hurt by the stuff.

  • james24 Jun 1, 2012

    The pet owner in your report said that she followed the directions, so using the product correctly doesn't guarantee that your pet won't experience vomiting, seizures, or worse.

    The EPA investigated spot-on flea treatments a few years ago and found that the labeling on those products was inadequate for safe use. They tried to get the product manufacturers to improve their labels, but little progress has been made to improve the safety of those products.