Cathy is a hero of the revolution for calling like 6 or 8 different after-hours vet clinics to find one that was willing to look at a rat.
 The verdict: From the perspective of "How much will the dog enjoy this outing?" we should stick with hiking. I deliberately picked a beach which allows dogs on, but not off, leash on the theory that this would mean there would be fewer other dogs for him to get overexcited about. In practice, there were a lot of dogs, most of whom were off-leash. We learned that Galen likes ocean water no better than he likes any other water that makes noise (i.e., not at all even a little bit HOLY SHIT IT'S TRYING TO EAT ME), so while he enjoyed the trip to a new and interesting environment, we will not be going back, as there are plenty of other equally new and interesting places closer to home with fewer other dogs in them.