It's not at all uncommon for me to call my vet for meds and simply go pick them up.. In my experience, most vets will do that, and they don't have to be particularly laid back -- you just kinda have to know what you're asking for, and why. If it makes sense to them, they'll usually do it...
I'm not saying your heart's not in the right place, and I'm not saying to put it down.. I'm just saying that this animal probably needs more than a syringe full of slurried food.
Have you tried calling a vet to ask about obtaining anything I mentioned earlier? The lactated ringer's alone...
The fact that it can't really open its eyes and can't hold its head up would seem to indicate some type of closed head injury, or perhaps a spinal cord injury.. Something related to trauma to the central nervous system.. The labored breathing with mention of broken ribs would point me toward a...