The plight of stray dogs and cats in the U.S. is well-known — some 5 million to 7 million of them enter animal shelters each year, according to the ASPCA, and most never make it out. About half of dogs and 70 percent of cats in shelters are eventually euthanized, and countless more die on the streets from illness, starvation or traffic.

But some animal advocates say there's also another, less obvious population of pets in need of help — or at least worthy of awareness. About 5 to 10 percent of the 3.5 million homeless people in America own dogs or cats, according to the nonprofit Pets of the Homeless, and in some areas the number is as high as 24 percent. These pets fall into a gray area of domesticity: They have owners but still must live on the streets, reliant on people who often already struggle to feed themselves.

This week (Aug. 7-13) is the second annual "National Feeding Pets of the Homeless Week," an event aimed at drawing national attention to the issue. Homeless people are frequently stereotyped as lazy or irresponsible, yet that doesn't jibe with someone who sacrifices his or her own meager resources to support a pet — in fact, the idea that hundreds of thousands of homeless Americans own pets suggests they aren't so different from Americans in general, argues Pets of the Homeless founder Genevieve Frederick. And since homeless shelters and apartment complexes often don't allow dogs or cats, she adds, some pet owners even remain homeless to protect their pets.

"Most people who experience homelessness are homeless for a short period of time, and usually need help finding housing or a rent subsidy," Frederick writes on the organization's website. But, she adds, those with pets need even more help. "Many are forced to choose between their pet or a roof over their head. Surprisingly, most choose to stay on the streets with their pets for longer periods of time."

Beyond raising awareness, Pets of the Homeless provides pet food and veterinary care to homeless people, awards grants to vets who volunteer their services, and awards grants to homeless shelters that allow pets. The group also compiles a list of pet-friendly homeless shelters, food banks and soup kitchens, and its website identifies collection sites where pet food and supplies can be donated.

Of course, while pets owned by homeless people are a compelling problem, they're still far outnumbered by pets that are both homeless and ownerless. The U.S. population of stray pets has shrunk in recent decades, thanks largely to spay-and-neuter campaigns, but up to 4 million dogs and cats are still euthanized every year, on top of countless others that never even make it to a shelter. That's the impetus for the upcoming "International Homeless Animals Day" on Aug. 20, which is dedicated to helping all homeless pets, including those with and without owners. Both events are especially important during the brutal 2011 heat wave, organizers point out, since homeless people and pets rarely have regular access to air conditioning.

For more information about Pets of the Homeless and International Homeless Animals Day, check out the videos embedded below: