Number of Animals Euthanized in US Annually

The number of animals euthanized in shelters in the U.S. for lack of homes is 4 million annually. 25% of these are estimated to be pure breeds. Source: Parade Magazine, Aug. 3, 2008, P. 14

Dog Euthanasia in Silicon Valley (Santa Clara County) and Environs

Why did dog euthanasia increase in the Silicon Valley area as its economy was turning around after the dot com bubble burst in March 2000?