Adverse reactions reported range from mild effects such as skin irritation to more serious effects such as seizures and, in some cases, death of the pet.

The agency is not, however, recommending or requiring any companies to recall their products.

EPA spokesman Dale Kemery says the EPA is not targeting specific companies -- just the products that may have contributed to the 44,263 incident reports the EPA received in 2008. Approximately 1,200 of those reports accounted for animal deaths.

The numbers mark a sharp increase from the approximate 28,000 incidents pet owners reported in 2007.

"There has been this increase and there is definitely a concern," Kemery said. "That's why we are investigating this.

"I'm not sure we can say there has been one group of reactions, but there are certain ones that have been most common, like skin problems, and some seizures have also been reported among certain animals. There have been reports of deaths."

Though the EPA is only now drawing more attention to this issue, spot-on flea and tick related incidents are not novel to the ASPCA's poison control center, according to Steve Hansen, ASPCA veterinary toxicologist and senior vice president of Animal Health Services.

In light of recent government scrutiny of flea and tick products, the ASPCA is cautioning pet parents to use care when applying any over-the-counter or prescription flea and tick solutions. Spot-on products--topical insecticides applied to the skin--generally kill fleas and ticks by targeting their nervous systems. But if misapplied, these products can have devastating consequences for our furry friends. Click here for more information from the ASPCA.

Source: U.S. Environmental Protection Agency, www.zootoo.com and The American Society for the Prevention of Cruelty to Animals