I look forward to see this exhibit in September. I have seen an open-topped Jaguar exhibit in Salzburg in Austria but it had a high fence. Jaguars are ground-dwelling unlike Leopards so while it is a bit of risk, you can do this. And Saint Louis has been keeping them in this exhibit without an accident since the late 1970s as far as I'm aware.
I just visited the comprehensive and excellent Saint Louis Zoo a couple of days ago, and the walls of the jaguar exhibit are massive. The section called "Big Cat Country" is definitely dated but the enclosures are so large that it still holds up well after at least 30 years or more.
