In Washington, a push to sterilize stray cats To curb the growing numbers of feral cats in the US capital, the Washington Humane Society is encouraging residents to set traps and bring the animals to a sterilization clinic, after which they are released.. For decades, standard procedure has been to round them up and euthanize them, but in recent years the trend has swung towards TNR -- trapping, then neutering, then returning cats to the places they were captured. A natural sound version of an AFPTV report.