Читать книгу Pet-Specific Care for the Veterinary Team - Группа авторов - Страница 262

In scrutinizing genetic reports in the literature, one must note that study bias is rampant in clinical research, even studies published in peer‐reviewed journals. Nonselection is defined as failure to include a subject or subjects from the population of interest in the experiment or study group; nonresponse is the failure to include a subject or subjects from the study population in the results and analyses of the study. Thus, for a disorder as common as hip dysplasia, prevalence data by breed are often contentious. Because submission of radiographs to most registries is voluntary, owners with dogs that are most likely to have hip dysplasia may see no reason to pay to have the radiographs submitted to the registry, which leads to substantial nonresponse bias and underestimation of the actual prevalence of hip dysplasia in these breeds.

This argument is not far‐fetched. Owners with dogs that have clinical evidence of hip dysplasia are not likely to ask to have radiographs taken because they know their animal will not be certified. Other owners, who have radiographs done thinking their animal is clear and learn that it has hip dysplasia, may elect not to have those reports sent to the registry, so as not to be stigmatized by the results.

Nonselection bias also plagues hip dysplasia statistics. Even if the registry decides to petition a national breed club, such as the ACCT Club, and asks all registrants to participate in a cost‐free hip evaluation plan to gather breed statistics on hip morphology, the potential for bias still exists. If the breed club has a strong policy of encouraging the breeding of only disease‐free dogs, might there not be dog owners who do not agree with those policies and therefore choose to not belong to the club? Or might there not be a sizeable population of owners of the breed who do not belong to the breed club because they are pet owners, not breeders? In any case, results cannot be extrapolated to the entire breed, just the frame selected for study.

Much of the research on which breed statistics for genetic disorders have been based is subject to nonresponse and nonselection bias. When bias is not addressed, readers are left to make their own assumptions on the basis of the results reported.

A better approach is for veterinarians to take a proactive stance and to consider preventive care on a pet‐specific basis whenever possible. In fact, understanding predispositions and risk profiles for individual pets allows veterinarians to create a lifetime care plan for most of their clients, based on the specific risks of each individual patient (see 1.2 Providing a Lifetime of Care), even if risk cannot be completely assessed.