The Need for Evidence

Over the past decade, human medicine has become more “evidence based.” Under this paradigm, recommended clinical policies regarding prevention, diagnosis, and treatment of diseases should be based on explicit evidence of the value of a particular approach. For example, whether or not a patient should be started on a daily aspirin for prevention of heart disease should be based on studies of such an intervention, and a weighing of the reported benefit of the intervention versus both the risk and cost of the intervention. The push for evidence based recommendations has resulted in certain traditional treatment approaches being abandoned and new ones adopted.

When it comes to human-animal medicine issues, including the use of animals as sentinels for human environmental health hazards, the use of animal assisted therapy for certain medical conditions, measures to prevent zoonotic disease in animal workers, and even the potential impact of adopting a “One Health” approach to disease prevention in the developing world, the truth is that there is a relative lack of “high quality”  evidence (such as controlled studies) either supporting or not supporting such interventions. This of course does not mean that such approaches are not worthwhile or do not hold potential for enhanced treatment and diagnosis of disease affecting both humans and animals (there is abundant anecdotal evidence that it may). Rather it means that there is a real need for research to test and rigorously evaluate such approaches. The Canary Database is an attempt to bring together published evidence about animals as sentinels of human environmental health hazards. Users can see “summary screens” that provide preliminary summaries of the strength of evidence that for a particular environmental hazard, particular species of animals may be either more susceptible, show shorter latency between exposure and disease onset, or have greater environmental exposure compared to humans. Advocates of “One Health” should be willing to see the concept tested objectively, and use the results to better hone future efforts to integrate human, animal, and environmental health.  Conducting studies that search for such evidence will better justify the commitment of health care resources in a human-animal medicine direction.