Population dynamics, overpopulation, and the welfare of companion animals: new insights on old and new data.

Americans profess a great love for their companion animals, and, indeed, their expenditures on food and other products for their dogs and cats would seem to confirm this. However, each year, many millions of dogs and cats are brought to animal shelters, where the majority are euthanized. Our inability to provide reasonably valid statistics related to this concern makes it difficult to offer a credible presentation on the need for a concerted effort to deal with the issue, design initiatives to ameliorate the problem, or evaluate progress and performance of these efforts. In this article we review some of the past efforts to document the scale of the "pet overpopulation" problem. We reexamine long-term shelter statistics from a single shelter system and present new data that reflect a recent cooperative effort to understand the origins and disposition of dogs and cats received by animal shelters.