At least nine class-action lawsuits are pending against makers of topical flea and tick products in the wake of a U.S. Environmental Protection Agency (EPA) investigation into safety of the pesticides used on dogs and cats.

One law firm in New Jersey has filed seven of the suits — one each against Merial Ltd., and its parent companies Merck & Co., Inc. and Sanofi-Aventis U.S., Inc., maker of Frontline; Summit VetPharm LLC and its parent company, Sumitomo Corp. of America, maker of Vectra; The Hartz Mountain Corp. and its parent, Sumitomo, maker of UltraGuard; Bayer Healthcare LLC, maker of Advantage and K9 Advantix; Sergeant’s Pet Care Products, Inc., maker of SentryPro; Farnam Companies, Inc., maker of Bio Spot and Adams; and Wellmark International, Inc., maker of Zodiac.

An eighth suit filed by a lawyer in California working with another New Jersey firm targets Hartz, Sergeant’s and Summit VetPharm.

A ninth suit filed by lawyers in Chicago and New York names Central Garden & Pet Co., Farnam, Hartz, Sergeant’s and Sumitomo as defendants.

The lawyers involved said more suits may be coming.

The burst of litigation represents increasing public awareness of potential problems with the popular parasite-control treatments, especially since an announcement by the EPA on March 17 that safety concerns are real and that tighter regulation and oversight are justified.

Jacqueline Mottek, a class-action and consumer advocacy attorney in Sausalito, Calif., said she has been “absolutely inundated” with calls from pet owners as a result of the EPA action and subsequent news reports.

She said the proliferation of suits reflects the fact that victims number in the thousands. The lawyers, she said, want “to make sure that people are represented. We also want to make sure that the courts understand the gravity and extent of this problem.”

The EPA’s investigation began about a year ago when it saw that the number of reported adverse events in pets exposed to topical flea and tick products topped 44,000 in 2008, an increase of 53 percent compared with the previous year.

The rate of incidents was 16 per 100,000 doses sold.

The agency did not have an explanation for the spike in reports. In an online discussion among members of the Veterinary Information Network (VIN), some veterinarians speculated that the increase in adverse events was related to an increase in pet owners buying products from retail stores rather than from veterinary clinics.

Dale Kemery, a spokesman for the EPA, said the agency did not collect information on where products were obtained. “However,” he wrote in a response by e-mail, “while we do recommend that pet owners consult their veterinarian if they have questions or concerns about use of flea and tick products, there is no reason to believe that products purchased from reliable sources are counterfeit or substandard, or that pet owners are not capable of reading and following product label directions.”

EPA officials have indicated that inappropriate use — such as treating cats with products made for dogs — was behind many adverse events, but Kemery said consumer error doesn’t explain everything.

“There are issues that go beyond misuse of the products,” he said. “We cannot attribute a particular proportion of incidents to inappropriate use versus other issues. Clarity of label instructions and the weight bands for doses are key issues that need to be addressed.”

Among the materials released by the EPA pertaining to its investigation are “data evaluation reports” for 21 flea and tick formulations. Each report details the total number of adverse events in 2008 associated with each formulation. That number is then broken into four categories: deaths, major events (causing life-threatening illness or long-term disability), moderate events (causing pronounced and prolonged illness requiring medical treatment) and minor events (causing effects that were minimally bothersome, with rapid resolution).

By reviewing all reports, the VIN News Service determined that Sergeant’s formulations accounted for the greatest share of incidents by far, with more than 11,500 total cases — the majority of those from a single product (registration number 2517-80).

Ranking second was Merial, maker of Frontline, with about 4,300 total incidents. Wellmark was third, with about 4,100 total incidents.

In terms of individual formulations associated with deaths, Zodiac for cats, registered by Wellmark, and also sold under different brand names by Farnam and Hartz, had the most, with 82 deaths.

ProMeris for dogs by Fort Dodge (now Pfizer), was next, with 47 deaths. Frontline Plus for dogs by Merial was third, with 44 deaths.

The meaning of such rankings is questionable, however, because the EPA did not supply sales figures, which would enable readers to determine incident rates for each product.

The agency omitted that information for two reasons, Kemery said: “Although we received information from the registrants on product sales or production, it could not be used for comparing incidents per doses sold due to differences in the basis of the information. In addition, if we had been able to calculate an ‘incident rate’ from sales data, we would not be able to release the sales information because registrants claim this information as confidential business information.”

Moreover, the EPA was unable to evaluate every adverse event reported. Cases for which clear information was not available are not included in the product-by-product analyses. The agency also did not verify incidents, but took the reports at face value.

Kemery said the EPA will require more standardized post-market surveillance reporting on adverse effects and require registrants to submit more sales information so the agency can better evaluate incident rates in the future.

In their presentation on March 17, EPA officials noted that all products were associated with deaths in 2008, suggesting that problems are common among topical parasiticides as a whole.

However, a popular perception exists that some products are more hazardous than others.

Richard Parsons, one of the plaintiffs in the case filed by Mottek out of California, has spent the past three years looking into problems with spot-on flea and tick products.

He has come to the conclusion that products traditionally sold by veterinarians, which historically have cost more — namely, he said, Frontline and Advantage — are safer than less-expensive products commonly sold in supermarkets or drug stores.

The product he particularly mistrusts today is Hartz Care Advanced Flea & Tick Drops Plus. That was the treatment Parsons said he used on his 6-year-old Scottish terrier, Duffy, back in May 2007.

Parsons, retired from sales and service positions with IBM and Siemens, lives in the desert around Palm Springs. He said fleas and ticks are not typically a problem there, so Duffy was not on a regimen for parasite control.

In the spring of 2007, Parsons and his wife returned from the Mississippi Gulf Coast where they had worked on a rebuilding project in the aftermath of Hurricane Katrina. Parsons was itching and thought he had picked up fleas. At the same time, the Parsons were preparing to send Duffy to board at his veterinarian’s facility while the couple traveled for a few days to visit children and grandchildren.

Not wanting Duffy to carry fleas to the kennel, Parsons said, he rounded up a vial of Hartz drops that he’d previously purchased, and applied it. He said he had used one of the three vials in the package once before and Duffy apparently tolerated it without a problem.

This time, Parsons said, was different. One day after the Parsons dropped off Duffy and flew out of town, a veterinarian at the clinic called to say that kennel workers had found Duffy having seizures. No one had any idea at first what the problem could be, but as Duffy’s condition worsened, Parsons said, a veterinarian working the second shift at the clinic asked if they had applied a flea and tick product recently.

“Of course, the answer was yes, and there we went,” Parsons said.

Dr. Perry Rhyneer, Duffy’s primary veterinarian, said the dog was given anti-seizure medication and muscle relaxants, to no avail. “Basically, he continued to go downhill from the beginning,” Rhyneer said. “We lost him about 24 hours later.”

Rhyneer said Duffy likely had an underlying kidney condition, diabetes insipidus, that may have predisposed him to reacting adversely to the pesticide. The condition was never definitively diagnosed because, aside from the fact that the terrier drank inordinate amounts of water, he seemed perfectly well, Rhyneer said.

“We had done a full blood panel on him a month before, and he was fine,” he said.

Parsons said he contacted Hartz and, after some persistence, ended up talking by telephone with company executives. He said the company reviewed the case and concluded that its product was not to blame for Duffy’s death.

Rhyneer said he finds Hartz’s position regrettable. “I just felt badly that the company would never admit that it could have played a part,” he said. “I’m positive, in hindsight, that (Duffy) did have a pre-existing condition, but they never would admit to any part, no way, that’s final and that’s it. I just felt they were very close-minded about it.”

Parsons said he wants three things from Hartz: An apology, reimbursement for Duffy’s $2,800 in medical bills and, most of all, a change in the formulation of its product to something safer.

Hartz declined to comment on the case because it is in litigation.

All manufacturers contacted by the VIN News Service declined comment on the class-action suits. However, they expressed support, for the most part, for changes being proposed by the EPA to address the safety of topical products as a whole. Those proposals include:

• changing brand names so cat and dog products are more distinguishable from one another
• narrowing the weight ranges for some products
• seeking more information on inert ingredients and prohibiting alternative formulas
• requiring standardized adverse event reporting
• requiring standardized sales reporting
• requiring a range of animal types be used for safety testing to account for variations in breed sensitivities, ages and body sizes
• pre-market clinical trials
• conditional registration for new products
• post-market surveillance

Despite manufacturers’ expressed support, working out the details of some of the proposals could get sticky.

For example, Joseph Conti, director of regulatory affairs for Summit VetPharm, noted that companies spend millions of dollars building brand recognition, so having to change the names of existing products is problematic. “I don’t think people will be receptive to it,” Conti said.

In the case of Vectra products, the words “dogs and puppies” and “cats and kittens” are part of the name, he said. The packaging, inside and out, includes images of dogs or cats, depending on the product. Moreover, the dog product is labeled “not to be used on cats” right on the vial, he said.

“If people are misusing it ... they’re obviously not reading it,” Conti said. “If somebody is not reading it, I’m not sure how changing the name will help.”

Dr. Michael Dryden, a professor of veterinary parasitology at Kansas State University, applauded the EPA’s proposals. “I would say, it’s about time,” said Dryden, whose expertise in the field has earned him the nickname Dr Flea. “Virtually everything they talked about will make things better.”

One addition Dryden said he would like to see is a requirement that pet owners obtain a prescription, or something equivalent to a prescription, from a veterinarian in order to buy a flea and tick product.

“Maybe you could continue to buy them someplace else, but I think they ought to be prescribed, just like any other medication,” he said. “You need that linkage. I think that’s one of the biggest problems we have is being able to purchase a lot of these products over the counter, because we don’t have that connection to the professional.”

Dryden added that despite the problems identified by the EPA, modern topical flea and tick products are far and away more effective and safer than parasite control products of 20 years ago.

“Animals used to die all the time from insecticide application,” Dryden said. “We were exposing ourselves (too) to these insecticides and these dips and these foggers. We are so much better off today than we were then.”