Clinical Trials in Pets: Less Expensive and More Promising

Our pets share not just our homes and hearts but also our life style and diseases. In many ways our dogs and cats are much closer representatives of humans than any test animal. So, can drugs be tested in a clinical trial in our pets to find out the ones that hold more promise in humans? NIH and the National Academy of Science think so, and for good reasons. This year NIH and NAS have increasingly funded clinical trials in pets and there have been some positive developments. While toxicology studies in animal models are well established in the regulatory requirements, efficacy studies are not. Efficacy studies in most animal models are considered unreliable predictors of efficacy in humans because such studies are conducted in specially engineered animals in sterile environment that do not mimic the human disease well. On the other hand, household pets get very similar diseases very much like their human partners. Unlike lab animals, which are highly inbred, pet dogs and cats are genetically diverse and are exposed to the same environmental factors as humans. Household pets get diseases, from cancer to arthritis to muscular dystrophy, same way as humans and mimic human symptoms. So, conducting a clinical trial in pets, just like humans, could yield results similar to human clinical trials at a much reduced cost. The clinical trials in pets are designed and executed very similarly to those in humans with repeat visits to the veterinarian principal investigator, scheduled tests at each visit, adverse event monitoring, and safety and efficacy endpoints. A clinical trial in pets is practically the same trial that would be run in humans but with animal subjects. By testing drugs in sick dogs and cats instead of lab rats or mice, one could get a much better perspective of human response. Even if the pet trial does not yield a human product, it could potentially yield new medicines for pet themselves making these trials financially more beneficial that say an animal efficacy study in a lab model.  However, trials in pets have their own limitations. First, there is no formal regulatory paradigm for using clinical trials in pets. FDA accepts data from pet clinical trials on a case-by-case basis, although unofficially FDA has been supportive. Second, since these trials are conducted on household pets, they have recruitment and protocol compliance issues similar to human clinical trials. Third, the pet trials are about 10 times more expensive than doing a similar efficacy study in a lab animal model. However, pet trials are about 10 times less expensive to an equivalent human clinical trial. So, these trials are a mixed blessing. If they work, they could be greatly beneficial but if they don’t, they would also yield a bigger time and cost loss. Fourth, pet clinical trials are hard to find. There is no official database on clinical trials in pets. Recently, the American Veterinary Medical Association has created a database for clinical trials in pets; however, it has limited information unlike clinicaltrials.gov which is a comprehensive and mandatory registry of human clinical trials. Unlike human clinical trials, there is no formal clinical trial application with FDA for clinical trials in pets and unless the drug is also subject to a human clinical trial, there is no mechanism to discuss the design, endpoints and study procedures with FDA for such trials in pets. Pet clinical trial protocols mostly require approval by animal care regulators which act similar to an IRB for human clinical trials. Overall pet clinical trials is a new and potentially very promising strategy particularly for new drug developers with limited resources and reasonable pet animal incidence of target disease.