WASHINGTON — Complaints of dogs and cats injured or even killed by flea treatments have increased significantly, the Environmental Protectionn Agency said today as it outlined plans to make the products safer.

The EPA says it will develop stricter testing and evaluation requirements for flea and tick treatments that are applied to pets’ skin. The agency also will begin reviewing labels to determine which ones need to say more clearly how to use the products.

The EPA’s effort follows increasing complaints from pet owners that the “spot-on” products have triggered reactions in dogs and cats, ranging from skin irritation to neurological problems to deaths.

Steve Owens, assistant administrator of EPA’s Office of Prevention, Pesticides and Toxic Substances, said new restrictions will be placed on flea and tick products, with additional changes for specific products as needed — including possible changes in their formulas.

Pet owners “need to carefully read and follow all labeling before exposing your pet to a pesticide,” Owens said.

The agency announced last April it was increasing scrutiny of topical flea and tick products because of the growing number of bad reactions reported.

The EPA said it received 44,263 reports of harmful reactions associated with topical flea and tick products in 2008, up from 28,895 in 2007. Reactions ranged from skin irritations to vomiting to seizures to, in about 600 cases, death of an animal.

An EPA spokesman said he did not have a breakdown of how many deaths were dogs and how many cats.

Dog and cat owners say their pets have suffered burns and welts on their skin; started to drool excessively; begun to shake uncontrollably; lost control of their legs or experienced other neurological problems after using the flea and tick treatments.

A 2009 study by the American Society for the Prevention of Cruelty to Animals reported that the majority of illnesses linked to proper use of topical flea and tick products were mild. Cats were more susceptible than dogs to illnesses and deaths from misuse of the products, the report said.

“The important take-home message is that although adverse reactions can occur with all flea and tick products, most effects are relatively mild and include skin irritation and stomach upset,” said Dr. Steven Hansen, ASPCA veterinary toxicologist and Senior Vice President Animal Health Services.

Pet owners should keep using the products as directed when faced with a flea infestation, Hansen said.

A statement released by Georgia-based Merial Ltd., which makes the popular Frontline tick and flea treatment, defended its own product.

“The number of adverse events reported for Frontline has remained consistently low since the product’s introduction in 1996,” the statement said. The vast majority of reactions are minor, the statement said.