When you’re looking to adopt a dog, you’re probably thinking of a sweet, quiet dog that comes right up to the cage and gives you those big puppy eyes that plead “take me home!”

But the shelter environment isn’t necessarily conducive to that, says Sasha Elliott, Greenhill Humane Society’s communication and events manager. She says Greenhill’s design, built in the ’50s, is outdated, meaning the kennels are “all facing each other, which can be extremely stressful for dogs that don’t know each other.”

This can mean that certain dogs may not share their personalities very well in the shelter environment, making them less attractive to potential adopters. That, and a number of other factors, can lead to a dog’s spending a very long time at the shelter before finding a forever home.

Take Tank, for example. This pit bull is 78 pounds of love, and he’s been at Greenhill since November 2016. He’s potty trained, nine years young, and loves short walks and lounging in the sun while chewing tennis balls. It’s his second stay there, Elliott says, because his first adoptive family had to take him back due to unforeseen circumstances.

In all, Tank has spent more than 500 days with Greenhill, waiting for someone to adopt him.

When it comes to adopting animals, Elliott says there’s a strong bias towards adopting younger dogs. Tank’s medical issues (he has some allergies that require a few medications) also make him less desirable in the eyes of many adopters.

And there’s this: “For Tank we are looking for a family where he would be the only animal. He has shown some reactivity with dogs and has a bad history with cats.”

All these circumstances make Tank a tough sell. His size and breed may be a factor as well. “I know there are some rental agencies around town that have a size limit,” Elliott says.

Many companies also refuse tenants with dogs of certain breeds. Campus Connections Property Management, for example, doesn’t allow pure breeds or mixes of Rottweiler, German shepherd, Akita, pit bull or chow, according to their pet policy.

So there are all sorts of barriers set up to stop Tank from being adopted. But what’s it like to actually live with him and love him?

Tim and Christina Bennett, his most recent foster family, say he’s a star.

The Bennetts have fostered 20 dogs in the three years they’ve worked with Greenhill, and Tank is high up among their favorites. “He’s a sweetie, he really is,” Christina says. “I hope someone picks him up. He doesn’t have any bad behaviors, doesn’t jump up, doesn’t chew things up.”

Tim thinks he hasn’t been adopted because of his age, but says Tank is young at heart. As for the ideal owner for Tank, Tim describes that person as “someone like a young professional who doesn’t have a lot of time to walk a dog three miles. I mean, he only needs a half mile.”

Christina adds, “Anyone who doesn’t want to spend a lot of time entertaining your dog, Tank is the dog. But he’s very affectionate and wants to be with you.”

Not able to adopt right at the moment? Christina says everyone should consider fostering. It fits their lifestyle after retirement, she says. “We decided we wanted to travel more, so I said we should foster. When we’re in town we can have a dog, and when we’re out of town we don’t have a dog.” Greenhill provides all the supplies necessary for caring for an animal, and all you supply is the love and the occasional behavior report, Christina adds.

Tim agrees. “I kind of have a philosophy where I can adopt one dog and help one dog, or I can foster dogs and help a lot of dogs.”

If you’re looking to adopt, consider asking the shelter staff this question: Who has been here the longest? You might just find a gem.

Interested in adopting or fostering for Greenhill? Go to green-hill.org to see adoptable animals, apply to volunteer, donate and more.