Ultrafiltered dog allergen skin test compared with acetone precipitated and conventional dog: A retrospective study

<b>Background:</b> Various formulations of dog allergen extracts, including conventional dog (also known as dog epithelium) and acetone precipitated (AP) dog, have been used for skin-prick testing (SPT), with AP dog showing improved antigen content but experiencing stability issues due to precipitant formation. Ultrafiltered (UF) dog extract has been developed to address these concerns by offering comparable allergen content to AP dog. This study retrospectively compared UF dog with conventional dog and AP dog in SPT. <b>Objective:</b> To compare the efficacy of UF dog extract with conventional dog and AP dog extracts in detecting dog sensitization through SPT. <b>Methods:</b> Retrospective analysis of SPT results from a single U.S. allergy clinic was conducted. Tests performed between October 2022 and March 2024 were included. Primary and secondary outcomes were analyzed by using descriptive statistics and statistical tests. <b>Results:</b> UF dog, AP dog, and conventional dog showed positivity rates of 24.2%, 23.5%, and 16.3%, respectively. UF dog demonstrated significantly higher average wheal and erythema sizes compared with conventional dog and AP dog, but UF dog was not statistically different from AP dog in terms of test positivity. <b>Conclusion:</b> UF dog extract showed comparable number of positive tests to AP dog and a greater number of positive tests to conventional dog. Results of the study suggest UF dog as a viable alternative to AP dog, which offered improved stability and similar test responses. Further research with larger sample sizes is recommended to confirm these findings.