Long-term evaluation of a zoned catch-neuter-vaccinate-release program integrating owner engagement and buffer zone strategies for humane dog population management and rabies control in Anuradhapura, Sri Lanka.

Abstract

Background and aim: Catch-neuter-vaccinate-release (CNVR) is recognized as a humane and sustainable strategy for controlling free-roaming dog populations and eliminating dog-mediated rabies. However, long-term evaluations incorporating spatial planning and community participation remain scarce. This study assessed a five-year zoned CNVR program integrating owner engagement and a peripheral buffer zone strategy in Anuradhapura, Sri Lanka, a religious heritage city affected by frequent puppy dumping and high densities of free-roaming dogs.

Materials and methods: From 2021 to 2025, sexually intact free-roaming dogs were captured along predefined routes with standardized effort, while owned dogs were voluntarily presented to clinics. The municipality was divided into three zones according to anthropogenic characteristics, and a surrounding buffer zone was progressively intensified. Population trends were analyzed using negative binomial regression models. A questionnaire survey conducted in 2025 evaluated anti-rabies vaccination (ARV) and sterilization coverage among owned dogs. Spatial and household-level factors influencing coverage were examined using generalized linear mixed models.

Results: The number of free-roaming dogs requiring sterilization declined from 1,368 in 2021 to 484 in 2025. Although annual declines in community dog counts per unit effort were not statistically significant, buffer zone interventions produced significant sex- and zone-specific effects, reducing male populations in zone 1 and female populations in zone 3. Owned dog numbers increased by 14.7% annually, primarily because female ownership increased by 24.1%. More than 78% of adult female dogs were sterilized. Questionnaire responses from 1,123 participants showed that 94.2% and 83.1% of owned dogs within and outside the municipality, respectively, had received at least one ARV, while annual vaccination coverage was 74.2% and 68.9%, respectively. Household-level analyses demonstrated that geographic location, rather than the number of dogs per household, explained most of the variation in vaccination and sterilization coverage, identifying several low-coverage locations that require targeted interventions.

Conclusion: A strategically zoned CNVR program incorporating owner participation and a boundary-sealing buffer zone effectively promoted humane management of the dog population and improved rabies control. Spatially targeted interventions and continued vaccination and sterilization campaigns are essential for achieving sustainable elimination of dog-mediated rabies in culturally complex urban environments.