Analysis of programs to reduce overpopulation of companion animals: Do adoption and low-cost spay/neuter programs merely cause substitution of sources?

Overpopulation of companion animal results in millions of deaths each year at shelters and spending in the billions of dollars. Major efforts are underway to reduce this problem, with one of the largest efforts being spearheaded by Maddie's Fund. Maddie's Fund programs focus on encouraging spay/neuter and adoptions through economic incentives and marketing. However, aggressive spay/neuter and adoption programs present economic questions regarding how much they simply lead to substitution of sources for these good and services rather than increasing total community adoption and spay/neuter levels. In addition, spay/neuter also presents an ecological question as to how effective it is at reducing population sizes and therefore shelter intake. Analysis of Maddie's Fund program results show that low-cost spay/neuter programs are effective at raising total community spay/neuter levels (i.e. they do not merely cause substitution in source of spay/neuter procedures). Similar results were found for adoptions, with animal control adoptions not being reduced by new adoption programs initiated by other organizations. However, no clear results were found demonstrating the impact of total spay/neuter procedures on shelter intake.