Variables associated with owner perceptions of the health of their dog: further analysis of data from a large international survey

In a recent study (doi: 10.1371/journal.pone.0265662), associations were identified between owner-reported dog health status and their diet, whereby those fed either raw food or a vegan diet were perceived to be healthier. However, the study was limited because possible confounding from variables not included in the analysis was not considered. The aim of the current study was to extend the earlier findings, using different modelling techniques and including multiple variables, to identify the most important predictors of owner-reported dog health. From the original dataset, two binary health outcome variables were created: the ‘any healthcare problem’ distinguished those that were healthy (“no”) from with those with illness of any severity, whilst the ‘significant illness’ variable distinguished those that were either healthy or had mild illness (“no”) from those with significant or serious illness (“yes”). Associations between these health outcomes and both owner-animal metadata and healthcare variables were assessed using logistic regression and machine learning predictive modelling using XGBoost. For the ‘any health problem’ outcome, best-fit models for both logistic regression (pseudo R2 0.428, P<0.001) and XGBoost (AUC 0.838, 99%-CI: 0.794-0.882) contained the variables dog age, number of veterinary visits and receiving medication. Several other variables were also included in the XGBoost model, albeit having limited although their importance was limited. For the ‘significant illness’ outcome, dog age, veterinary visits and receiving medication were again the most important predictors for both logistic regression (R2 0.349, P<0.001) and XGBoost (AUC 0.871, 99%-CI: 0.799-0.944), whilst location (UK) also featured in the latter. No other variable was of sufficient importance to be included in the final model. The results of the current study conflict with previously-published research using the same dataset and suggest that diet the fed has limited impact on owner-perceived dog health status; instead, dog age, frequency of veterinary visits and receiving medication are most important.