Upper respiratory infection in shelter cats is strongly associated with feline herpesvirus infection, and herpes is specifically activated by stress. Building on the discovery that larger, compartmentalized housing was associated with decreased risk for URI, we compared stress levels in cats in 2-compartment cages with > 8 square feet of floor space, with levels in cats housed in traditional ~ 2’ by 2’ single cages. The results were dramatic and poignant: on average, cats in the larger cages reached a “relaxed” behavioral score (< than 3) by day 2, while cats in the smaller cages hadn’t reached that level even after a full week in the shelter. Adapting quickly to the shelter not only means happier cats – it means cats moving on to homes sooner and more lives saved over time.