Are sniffer dogs a reliable approach for diagnosing SARS-CoV-2 infection?

Objectives: Despite inter-individual variations in their diagnostic efficiency, dogs have been trained to investigate many human pathologies, especially cancer, diabetes, migraine, seizures and even infectious diseases. To this end, we performed a critical review and pooled analysis of current scientific literature on the performance of dogs trained for identifying severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive human specimens. Methods: We carried out an electronic search in PubMed, Scopus and Web of Science with the keywords "dog(s)" AND "sniffer" OR "scent" OR "smell" AND "SARS-CoV-2" OR "severe acute respiratory syndrome coronavirus 2" OR "coronavirus disease 2019" OR "COVID-19" within all fields, without date or language restrictions, to identify studies describing dogs' performance for identifying SARS-CoV-2 infected material. Results: Three studies could be finally included in pooled analysis, totaling 17 dogs (47% females), aged between 0.5 and 12 years. The pooled diagnostic sensitivity was 0.88 (95% CI, 0.84-0.91; I-2, 85.3%), the diagnostic specificity 0.99 (95% CI, 0.99-0.99; I-2, 97.4%), whilst the area under the summary receiver operating characteristic curve (SROC) was 0.979 (standard error, 0.003). Conclusions: The notable performance observed in this pooled analysis would persuade us to suggest that adequately trained dogs could represent an intriguing and sustainable resource for purposes of rapid SARS-CoV-2 mass screening.