Pet owners and authorities are starting to worry about the safety of animal medicines echoing worries regarding human drugs such as Vioxx.
Tested on only a couple hundred animals, a drug meant for pets is less likely than a drug for humans to show all its failings and shortcomings until it reaches market, say veterinarians. Over 700 drugs have been approved for pets, but several others are used legally without approval explicitly for animals. In fact, most drugs for pets are first developed for people.
These concerns are arising at a time when an intensive demand has made the FDA hire more reviewers to sort through research quicker to decide whether or not new pet drugs should be approved. Given that the pet market is smaller, many companies save on costs by relying on cheaper experiments with approximately a tenth as many subjects as in human tests.
Dr. Stephen Sundlof, the vet who directs the FDA’s Center for Veterinary Medicine, says if the agency insisted on the same size studies as for people, “we would have very few drugs” with formal approval for pets. But he adds, “The rigor is every bit as great as with human drugs.”
Since the year 2000, reports of side effects in animal drugs have gone up about 90 percent, to 34,603 last year, FDA records show. The agency ties the growth to new types of drugs and greater understanding of potential dangers – not worsening safety. However, vets say that the vast majority of side effects are never reported, so it’s hard to gauge overall safety.
Some clients complain that most vets hardly ever speak of the possible side effects when they recommend a drug.
In 2004, Pfizer without admitting any wrongdoing paid out nearly $1,000 to 300 pet owners to settle a lawsuit.
Rimadyl, used by over 10 million dogs since 1997, is tied to over 3,000 pet deaths, shows FDA data. Most of these pets, dogs in particular, have damaged livers and/or kidneys.
Rimadyl is in the same brand NSAID family of drugs as Vioxx. Although, unlike Vioxx, it has remained on the market.
The FDA stresses the need for medicines like Rimadyl, partly because pets cannot tolerate the range of pain-killing alternatives that humans can. Dogs are more sensitive to aspirin than humans. And a single Tylenol can kill a cat.
But sometimes a drug’s risk is too great to accept. A heartworm medicine, Proheart 6, was pulled from the market in 2004 after FDA researchers found evidence of fatal side effects.