I’m not agreeing or disagreeing with anyone but some dogs can be very different in a shelter vs a home they’re comfortable in. When we found our boxer 4 years ago we brought him home to try to find his owners.

He let our 35 lb dog get close, and then lunged. A day or two later, we legally had to turn him into our local shelter for 14 days to see if anyone claimed him. After the 14 days our local shelter AND sanctuary said he was good with dogs, but didn’t like to play. Once we brought him home he started being reactive. Just like we told them he was, and they swore that at the shelter, in one on ones, in play groups, at the sanctuary, everywhere…he wasn’t reactive. With more help with a sanctuary trainer we guessed that he just felt protective of the “home” environment, since he likely was a junkyard dog before, and was thinking he needed to protect high value humans, or humans he loves.

We were told dogs can be one way in shelters and another in homes they feel safe in. They can start to “defend” their people/home.

However, lots of shelters are negligent and don’t do these tests. I’m not saying the shelter OP dealt with was perfect, I think a lot of shelters just rush to adopt our dogs and can sometimes miss or even downplay reactivity.

That said, some dogs truly do react differently in different dynamics, and a shelter is a unique dynamic.