Are human beings and dogs too different for medical research on dogs to help understand human disease? A number of animal rights activists were practically gloating when a Novartis spokesman appeared to say so in January.
Novartis had its hands slapped by the Food and Drug Administration over its failure to timely report about the death of dogs taking Deramaxx. Deramaxx is a COX-2 inhibitor that is used as a painkiller in dogs after surgery. COX-2 inhibitors have come under a lot of scrutiny recently due to studies suggesting they may elevate the risk of heart attacks.
The FDA complained that Novartis had not timely reported deaths of dogs who were given Deramaxx. Reuters quoted a spokesman for Novartis, however, as downplaying any link between the dog deaths and the problems reported in human beings with COX-2 inhibitors,
Joseph Burkett, a spokesman for Novartis Animal Health Services, said the cardiovascular problems linked to such drugs for people were “not an issue” for dogs, because canine hearts are different from those of humans.
Obviously, a pharma official seeming to say that dog and human hearts are too different for research on one to be relevant to the other was a nice gift to the animal rights activists, but it was also inaccurate and deceptive. Either the spokesman or the journalist simply screwed up and oversimplified why the deaths in dogs are probably irrelevant to human beings in this case.
The reality is this: COX-2 inhibitors appear to elevate the risk of heart attacks in human beings who already suffer from hypertension. Hypertension is simply not a prevalent problem in healthy dogs. As Novartis noted on its web site,
The cardiovascular risks suspected to be related to coxib-class NSAIDs in people is extremely unlikely to be an issue in dogs. The risks associated with these drugs in humans involve an increased risk of heart attacks, especially in patients with hypertension (high blood pressure). Heart attacks and hypertension are rarely an issue in healthy dogs. A heart attack occurs when one or more vessels that supply the heart muscle itself with blood become blocked. The blockage is usually caused by cholesterol accumulation along the walls of the blood vessels. This condition is called atherosclerosis, or Â“hardening of the arteries.Â” Heart attacks in dogs are rare because dogs are extremely unlikely to get atherosclerosis and dogs have a higher number of vessels which supply blood to the heart. Thus, if one vessel becomes clogged there are additional vessels that supply blood to the heart. High blood pressure is also not a problem in healthy dogs since hypertension in humans is heavily influenced by lifestyle (stress, diet, exercise and smoking).
So if you wanted to study the effects of a hypertension drug in an animal model, healthy dogs would not be your first choice. Typically in studying hypertension with dogs, hypertension would be induced surgically.
FDA links dog deaths to drug. Reuters, December 29, 2004.