Study: Sterilization Is Best for Controlling Feral Cats
Feral cat populations managed with a high-intensity “trap-neuter-return” (TNR) program can see upward of 30 times fewer preventable deaths over 10 years, according to a study from the Alliance for Contraception in Cats & Dogs (ACC&D). Researchers used a simulation model to evaluate different population management strategies for unowned cats over a 10-year period.
The study, published in Frontiers in Veterinary Science, found TNR was successful in controlling the number of feral cats, while also drastically reducing instances of preventable deaths as compared to other methods, such as removal or culling.
TNR is the method of humanely trapping unowned community or feral cats, having them spayed/neutered and vaccinated against rabies, and then returning them to their colony.
“The effectiveness of TNR programs often is debated, but less commonly is defined well,” says John Boone, PhD, ACC&D board vice chair. “TNR groups most often track numbers of sterilizations performed and cats entering or euthanized in shelters as measures of effectiveness. These metrics are important, but they do not measure reduction in numbers of outdoor cats or illustrate how management translates into “lives saved” in an outdoor cat population.”
Researchers also noted TNR was significantly more effective when implemented with high intensity, rather than at lower levels.
The study authors examined seven management scenarios of feral cats, including: (1) taking no action, (2) low-intensity removal, (3) high-intensity removal, (4) low-intensity episodic culling, (5) high-intensity episodic culling, (6) low-intensity trap-neuter-return (TNR), and (7) high-intensity TNR. For each scenario the researchers tracked the number of kittens born, the number of kittens surviving to adulthood, and the number of adults removed using lethal control over the entire 10-year simulation. For the study, the researchers defined all kitten deaths and lethal removal of adults as “preventable” deaths because they could potentially be reduced by employing a management strategy. “The simulation results suggested that the cumulative number of preventable deaths over 10 years for an initial population of 50 cats is highest for a “no-action” scenario, estimated at 1,000 deaths,” wrote the authors. “It is lowest for a high-intensity TNR scenario, estimated at 32 deaths, a 31-fold difference.”
“Sadly, many communities still opt to do nothing to control populations of community cats or use outdated, ineffective methods —such as sporadic trapping and removal,” says Margaret Slater, DVM, PhD, one of the study’s coauthors. “This research confirms high-intensity TNR is the most effective, humane way to stabilize a population of community cats and, over time, reduce them.”