LITTLE ROCK — Dr. Holt Pittman, a Helena-West Helena veterinarian, was stumped. At least 100 dogs a year, all taking Heartgard Plus, were still contracting heartworms, a parasite that causes lung disease in dogs, and possibly death.
While some cases stemmed from owners’ skipping doses, many were coming from Pittman’s most diligent clients, he said.
A lawsuit by a former employee of Duluth, Ga.-based Merial, maker of Heartgard, may answer Pittman’s concerns.
Dr. Kari Blaho-Owens, Merial’s former head of “global pharmacovigilance,” alleges that Heartgard has been losing its effectiveness for years, and that Merial executives knew about it. She claims she was fired in July after refusing to destroy documents relating to Heartgard’s effectiveness.
According to the lawsuit, filed last month in the U.S. District Court for the Northern District of Georgia, “Merial has been aware of a serious lack of efficacy” since 2002, even as it continued to market Heartgard as “100 percent” effective. Merial stopped calling Heartgard “100 percent” effective in 2006 after four years of FDA requests, according to the suit. The company did not explicitly state that contracting heartworms was possible while the pet, whether dog or cat, was under properly administered Heartgard, the suit says. It just changed the packaging to say “effective.”
Blaho-Owens also claims the efficacy data Merial submitted for FDA approval of Heartgard weren’t consistent with post-approval reports Merial submitted to the FDA.
Blaho-Owens found that about 20 percent of dogs treated with Heartgard regularly contracted heartworms. “There was no other explanation possible other than product failure,” the lawsuit said.
Pittman said Merial blamed the problem for years on owners who forgot to give their dogs the beef-flavored medicine once a month.
“We’ve known there’s been a huge problem for years, but what makes me mad is that Merial knew there was a problem, they had a researcher who knew there was a problem, and they were trying to cover it up,” said Pittman, who stopped recommending Heartgard Plus for his patients early this year. “If this was a human product, it’d be on the national news.”
Some dog owners whose pets got heartworms while on Heartgard had their treatments paid for by Merial over the past eight years, Pittman said. Two dogs owned by Erin Collins of Helena-West Helena contracted heartworms within six months of each other last fall. The treatment was too dangerous for her 11-year-old Labrador, but Merial paid the $300 bill for her 3-year-old golden retriever-poodle mix. “Merial stood by their [promise by paying for the treatment], but I wouldn’t use it again. I’ve lost confidence,” Collins, 50, said. She has since switched to ProHeart 6, a twice-yearly injection by Pfizer.
Merial denied in a news release that there were any problems with Heartgard. “As a matter of company policy, we do not comment on the details of pending litigation or on employee-related issues. However, Merial believes we have acted appropriately and responsibly in all matters related to the allegations,” the statement said. “Merial stands by the effectiveness of our products.” The company calls Heartgard the No. 1 “veterinarian-recommended heartworm preventative” on its website.
The Mississippi Delta in particular has seen an increase in heartworm infections in dogs taking preventives such as Heartgard, American Heartworm Society President Dr. Wallace Graham said. Heartworm larvae are carried by mosquitoes, which are plentiful in the Delta.
“In the Delta, with the amount of mosquitoes we have, you have to hit them hard and keep hitting them. You’re just going to have so many larvae in these dogs,” said Dr. Andrea Allbritton, a veterinarian in Lake Village.
But it’s not just the number of heartworm larvae that concern Delta veterinarians. There are a growing number of anecdotal reports suggesting heartworms in South-Central states are resistant to medication, said R. Kelly Schwalbe, a spokesman for the Companion Animal Parasite Council.
Merial knew about this resistance too, Blaho-Owens’ lawsuit claims, and was working to add more drugs to Heartgard to make it more effective.
Business, Pages 23 on 06/21/2011