As cat lovers, we at Modern Cat advocate for TNR as the humane way to care for feral cat colonies. But is there possibly a better way? The Journal of the American Veterinary Medical Association compared three methods of feral colony control: trap-neuter-return (TNR), trap-vasectomy-hysterectomy-return (TVHR), or euthanasia. The result? Researchers found that TVHR meant that fewer cats needed to be trapped and treated for colony elimination compared to TNR (only 35%, compared to 82% for TNR). Although the study still found TNR to be an effective strategy for colony management, researchers theorized that TVHR is more effective. Why? The idea is that when male cats are not neutered, but just rendered infertile, they can retain their role as the dominant cat in the colony, and thus are not replaced by an unneutered male. (A vasectomy leaves the testicles intact, meaning that hormone production is not affected.)
A downside is that when the cat's hormone production is left intact, some of the benefits of neutering are lost, like a reduction in cat fighting, spraying and aggression. It's clear that there is no cure-all to the challenge of feral cats; further research seems to be needed to find an effective and compassionate solution.