Most of the purebred dogs in shelters are pit bulls. Sadly, theyre among the least wanted dogs in the US. Homeless Animal Statistics: How Many Pets Leave Animal Shelters? The stigma surrounding shelter animals has been lifted over the years, and people tend to adopt instead of shop for a pet. But, sadly, not all homeless animals get adopted. 14. 710,000 strays are returned to their owners each year. (ASPCA, DoSomething) Out of all the strays that enter US animal shelters, 620,000 dogs are ...