Nail clippers and file. Snakebite kit?

The muzzle is key. Some folks will throw in a couple sanitary napkins, which can be used in lieu of gauze pads or to pad an injury. I'd also take an old IV bag or two - they make admirable, durable temporary protective boots. You may want to throw in an heavy-duty oversized sling in case you need to carry the pup out.

I'd also throw a "cone of shame" in the vehicle. Disassembled flat, they take up next to no room.

fiery, dependable, occasionally transcendent