Can garlic prevent, repel or kill fleas that infest dogs?

PICO question In dogs, is oral or topical administration of garlic, compared to no treatment, efficacious at preventing or reducing parasitism by fleas?   Clinical bottom line Category of research question Treatment The number and type of study designs reviewed Zero Strength of evidence Critical appraisal of the selected papers meeting the inclusion criteria collectively provide zero evidence in terms of their experimental design and implementation Outcomes reported The outcomes reported were none Conclusion It is concluded that there is a lack of peer-reviewed scientific in vivo evidence to address the PICO   How to apply this evidence in practice The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources. Knowledge Summaries are a resource to help reinforce or inform decision-making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.