Letter to the Editor

Thank you for the opportunity to respond to the letter of Dr McKenzie regarding our recent publication “Results of Screening of Apparently Healthy Senior and Geriatric Dogs.” In this article, we document clinical and laboratory abnormalities in elderly dogs that were considered to be healthy for their owner. We agree with Dr McKenzie that not every abnormality is necessarily clinically relevant and that it remains to be proven that earlier detection of certain abnormalities will lead to improved longevity and/or quality of life, as was also stated in our article. We thank Dr McKenzie for giving us the opportunity to elaborate further on this important issue. We agree that further research to evaluate the actual impact of health screening on the morbidity and mortality of veterinary patients is warranted. However, it is important to be cautious with extrapolating findings from human medicine to veterinary medicine as the situation in veterinary medicine might be even more complicated compared to human medicine. Veterinarians have to rely on observations made by the owner, who is often unable to recognize subtle or mild clinical signs, resulting in a further delay of detection of potentially significant abnormalities. It is the responsibility of veterinarians to assure a thorough history is taken, ideally based on a questionnaire, to obtain the necessary information as a part of health screening. For example, several owners in our study did not detect or appreciate polyuria/polydipsia as a problem; however, this finding is often clinically relevant, and further examination is warranted in those cases. Health screening is also of value to provide baseline values for an individual dog. For example, for dogs suffering from white-coat hypertension, antihypertensive treatment is indeed not beneficial, but knowing which dogs are sensitive to stress will facilitate interpretation of future blood pressure measurements and may also give the opportunity to train dogs to the blood pressure measurement procedure. The limitation of a single blood pressure measurement was addressed in the manuscript. Further, to improve interpretation of laboratory abnormalities, the use of subject-based reference intervals could be beneficial, which warrants baseline values. The IRIS staging system already recognizes the clinical importance of serial increase in serum creatinine within the reference interval to support the presence of chronic kidney disease stage 1. The early detection of chronic kidney disease and institution of a suitable treatment has already been proven to be beneficial, but data are lacking for most other diseases. Thus, results of health screening tests need to be critically evaluated by veterinarians. In case of questionable clinical relevance, a follow-up will be more appropriate than immediate further diagnostics or treatment. In conclusion, we definitively agree that further studies, ideally with long-term follow-up, are needed to provide evidence for the exact benefit of screening, clinical relevance of some detected abnormalities and importance of overdiagnosis in veterinary medicine. We want to point out that these goals were outside the scope of our manuscript. Until these data are available, we think that there are currently more arguments “pro” health screening than “contra,” provided that results are critically interpreted.