I assume this is a temporary exhibit while the lion is young. I cannot believe they could get a USDA license to keep an adult lion in there.
I can't see any overhang on the inside of the cage either, which is what surprises me most since even a young cat could, I think, scale that wire without much difficulty. Unless there's a single strand of electric wire at the top that we can't see. Certainly big-cat enclosures in the UK are often some of the most secure; often with double wire and very high with overhang and nothing near the edge to allow the cats to jump. Hope the cat and dog do well
