We are due at the Fort on Sunday the 4th. We have a preferred pet loop reserved (and confirmed by phone last week). So is 300 still closed? If so I guess I'll request 500 as our backup since we want to be near the dog park!
We left Thursday 9/24 after staying in loop 500 for 14 nights. They were still working on loop 300 when we left, but seemed to be doing the "finishing touches".
One problem with that - 500 is a Premium loop. On the off chance 300 isn't open, unless they upgrade you to Premium, they'll quite possibly put you in 100 or 200 (the only remaining Preferred loops)
These days it seems they'll put the "overflow" pets in just about any loop - probably more likely then them giving you the upgrade, but you never know. There have been reports of dogs in 100 & 200 and lots of other loops that aren't officially designated as pet loops.