Managing free-roaming domestic dog populations using surgical sterilisation: a randomised controlled trial

Free-roaming domestic dogs (FRDs) are among the most abundant carnivores on earth and have coexisted with humans for over 15,000 years, yet increases in negative interactions and the transmission of zoonotic diseases, precipitates calls for population management. Despite significant investment in FRD sterilisation in India, where rabies is endemic, there is limited evidence of its impact on reducing FRD population sizes. Therefore, robust evaluation of the effectiveness of fertility control programmes is necessary. To address this, we implemented a Before After Control Intervention (BACI) framework in the first multi-site randomised controlled trial for the sterilisation of FRDs. We conducted single intensive sterilisation campaigns in five areas, achieving female sterilisation coverages of 58-66%. We observed a decrease in puppies and lactating females and a reduction in residents' reports of barking, a common problem associated with FRDs. There were no significant differences in adult FRD counts between intervention and control sites during the 2-year follow-up. However, unmeasured immigration into and emigration out of study areas may have confounded counts. One-off, albeit intense, sterilisation campaigns in open populations require substantial investment and are unlikely to reduce population size in isolation, though there may be some reduction in problematic behaviours and improved animal welfare.