Thanks, Chris.

I'm still a little worried, though. Max is a very physically fit dog and his belly usually doesn't reach down nearly as far as his chest does. Now it's just straight across - but it's not so swollen that you can see it sticking out when you look down at him from the top.

I don't know what he might have eaten, and I know big dogs are prone to gastric torsion. He ate, and he hasn't vomited or tried to vomit, so I'm not freaking out. Maybe it's just full of a lot of gas. He's been passing unusual amounts of it today!