EXCELSIOR SPRINGS, Mo. -- Bailey, a 3-year-old cat, was very ill.

Medical tape wrapped around her paw kept an IV needle in place. She was exhibiting signs of hyper-sensitivity. Each of her breaths was more labored than the last.

Pam Russell had already lost one cat that week and didn't want to lose another.

She said a common pet product killed her other cat, Radar, a stray she'd taken in almost two years earlier.

"By Monday morning (June 30) he could hardly move, so I brought him in and they hooked him up to IVs and checked his blood work and he never got any better, and he died Tuesday evening before I got up here," Russell said.

It started just days earlier after Russell said she applied an oil-based, over-the-counter flea and tick repellant bought at a local Wal-Mart.

She said she followed the directions and applied just a few drops of the product to four of her cats, but by the next morning she said something was wrong with two of them.

"And by Wednesday morning, she was worse and we put her on IVs yesterday, and she's gone downhill since," Russell said.

Russell said she believes both cats' reactions may have been caused by the flea treatment, which is manufactured by Hartz Mountain out of Secaucus, N.J.

Dr. Pete Rucker, a veterinarian with Excelsior Springs Animal Clinic, treated both of Russell's cats.

"The history on this cat is that he was fine until the over-the-counter flea product was applied," Rucker said. "These are typical symptoms that we've see with hyper-exposure to this product."

Although hundreds of thousands of animals get treated with products like this every year without any problems, he typically sees at least one or two cases like this every summer, Rucker said.

"Normally they start off with hyper-salivation, maybe twitching, maybe hyper-sensitivity," Rucker said.

There's no way for him to tell definitively if Bailey is reacting to the flea and tick product.

"We have tested Bailey for some other diseases, and so far those tests have come back negative," Rucker said. "We can't rule out other causes, but the symptoms still do correspond with what we would expect to see."

In 2005, the EPA pushed Hartz to yank two flea and tick treatments off the shelves after it was found they "may be associated with a range of adverse reactions" including "numerous deaths in cats and kittens."

But while the Hartz product used by Russell was evaluated by the EPA, it was not considered to be a source of adverse reactions at that time.

In a statement, the EPA told KCTV5 News that "while there have been some incidents reported to EPA related to use of this product, they have been many fewer in number and lesser in magnitude ..." than those that were recalled.

"Seems to be they were fine before we put the product on, and now we're sick," Rucker said.

According to a memo from the EPA at the time, "a total of 202 deaths" were reported for the same product Russell used, but the EPA discounted the majority of those cases because of what it called a "lack of detailed information" or the possibility the cats were "exposed to another insecticide."

"However, 5 cases" -- the deaths -- "were categorized as probable or possible," according to the memo.

"Because of the way cats groom each other, they lick the product off of another animal, and once they get it internally, oral ingestion is far more toxic than the dermal contact," Rucker said.

Todd Phillips is a toxicologist with the EPA, the agency responsible for regulating products like the Hartz flea and tick repellant, but Phillips said investigations and evaluations are consumer-driven.

"It's very important to let your veterinarian know to report that information to the National Pesticide Information Center so that the agency is aware of any incidents that occur," Phillips said.

But are these incidents really being reported?

Here's an exchange KCTV5 News had with a sales associate at PetSmart.

KCTV5: "Do you guys carry the Hartz brand as well?

PetSmart: "Yeah, we do."

KCTV5: "Have you heard anything about that?"

PetSmart: "Umm, a lot of people don't like it."

KCTV5: "Really?"

PetSmart: "Yeah."

KCTV5: "Why not?"

PetSmart: "I don't know. But every time, like someone asks me like ... they call on the phone or something and ask what we have, and they're like, 'Not Hartz.'"

KCTV5 contacted Hartz Mountain about its Ultra-Guard One-Spot Treatment and the company said in a statement that "There is no evidence in the scientific literature to support the claim that this product has ever caused the death of any cat."

The statement goes on to say, "Our products are safe and effective when used in accordance with label directions."

That's little consolation for Russell, who found herself grappling with a difficult decision.

"I mean, we try to do the best, to give them everything and get them through this, but I don't know. I'm afraid I'm going to have to make a decision on her and have her put down because I don't think it's going to get better," Russell said.

She didn't have to make that decision. A few hours after her interview with KCTV5, Bailey died at the veterinarian's office.

Hartz also emphasized that methoprene, the active ingredient in this product, is virtually non-toxic, making it virtually impossible for it to have caused the deaths of Radar and Bailey.

However, according to the EPA, the health problems reported with the two products that were pulled in 2005 were likely due to the inert ingredients in the formulation being toxic to cats.