Not directly to OP's question, but a new chain of vet clinics with an urgent care model is opening soon all over the DMV: 2 DC locations (afaict), Bethesda, and Arlington:
https://bondvet.com/ .
They seem to be focused on same-day appointment availability for situations that don't rise to the level of an ER visit. I hope that will take a little of the pressure off the area ERs. I know for myself I used to use the vet ER for things that worried me but weren't really hospital-worthy, and now I'm much more circumspect about not adding to the crush in ERs with more minor things.