Research Comparing Costs of Trap/Neuter/Return (TNR) and Euthanasia

A recent study done by experts in population modeling, economics, wildlife conservations, and animal welfare used computer simulation modeling to compare the cost of Trap-Neuter-Return (TNR) versus euthanasia to manage the population of free-roaming cats (FRC), also referred to as community cats. There have been debates among animal welfare organizations, wildlife conservation organizations, and policymakers about whether the lethal or non-lethal strategy for FRC management has the most efficient outcome. The goal of this study was to provide scientific data, which in combination with community goals, priorities, and legislation provide a framework to identify and support policy and management for FRC. 

Study Design

Researchers used computer simulation modeling to represent the FRC population over 10 years with the starting point of 25 female cats and 25 male cats. The study then estimated and compared trapping effort, cost, and FRC final abundance for each of the management scenarios. 

Study Results

Out of the 14 scenarios compared, 5 resulted in about a 45% decrease in population size. Of these 5 scenarios, 3 involved removing cats (either for euthanasia or adoption) and 2 neutering and returning cats. The study revealed that both removal and neuter-return could reduce the FRC population substantially if performed with high intensity at the beginning of implementation.  All of the management scenarios were ranked from most cost efficient based on a per cat reduction in final population size. While removing and euthanizing 75% of all cats every 6 months had the highest per cat efficiency, total cost was higher than 75% TNR which was the second more efficient approach. However, the 3 scenarios that exclusively relied on euthanasia for a 45% decrease in population size were more expensive than the comparable 2 scenarios that relied exclusively or primarily on sterilization. Adoption of removed cats substantially increased costs compared to either euthanasia or TNR but can lead to smaller final population sizes.

Study Takeaways

This research determined that TNR could have excellent results by “frontloading” sterilizations using a high intensity at the beginning of implementation. This technique yields substantial FRC population reduction over time and was shown to be cost-effective. The abandonment of cats substantially increases the effort and cost needed to decrease FRC populations so approaches to help decrease this will be helpful. The goals of any FRC initiatives must be clearly determined and include how to measure success of those goals.

Consider how your organization can shift to a goal of reducing the population of community cats. You may need to adjust to doing strategic, focused Trap-Neuter-Return-Manage, a more active approach to TNR that includes monitoring and providing additional support to cats in a designated area.