Paula Fasseas, founder and executive chairman of PAWS Chicago, said she started the shelter as a grassroots organization in 1997 after learning that every year more than 42,000 homeless animals were being euthanized in Chicago.

Animal shelters across the city are seeing an increase this year in the number of pets coming through their doors. What’s behind that trend — and how shelters are trying to keep pets in homes.

Chicago animal shelters like PAWS are still coping with the spread of a new, highly contagious strain of canine influenza. In the U.S., the outbreak of the H3N2 dog flu virus was first found in Chicago last year. It's now spreading to western states.