Some ideas for dogs that don't want to take medication
I know firsthand from working with a dog who couldn't really get on the right side of pain control just how hard it is. It's such a nasty cycle. Pain affects appetite too so it can be more than just not trusting food per se or feeling like he's been forced that's making it hard for him to eat. Again, I went through that with Mira after her femoral head osteotomy. It was many days of force feeding, numerous trips to the vet and to the emergency clinic. It was horrible.
I have a couple of thoughts. First, can you either find low sodium chicken broth or, better still, make some salt free chicken broth so that he'll be getting fluids? If he starts drinking a little more, you can add a little bit of tiny shreds of chicken to the broth too. With his UTI, it'll be important to keep fluids moving through him and hopefully he'll drink some broth.
I'd water the broth down significantly. It doesn't have to taste like soup to him; we just want him to get fluids in him without it being a struggle and hopefully the chicken flavoring will cause him to drink a little more. You can make a very weak flavored water with a little bit of liver boiled in water too but you run a much higher chance of ending up with a dog with diarrhea. (again, speaking from experience here.) I'd go for the chicken broth water myself. <g>
With regard to the pills, you've probably tried a whole range of things but I'm not sure of details or anything so I apologize if you've already tried this. First, if you can give him his pills in the treat item while he's actually AROUND the other dogs (and not run the risk of them eating the meds) that can help a lot. I find that my dogs that would ordinarily roll their eyes at something think it looks MUCH MUCH BETTER if there's another mouth right there waiting in line for their share of the yummy treats as well. You can still give him a few "blanks" (which is a great idea) but if he has to wait and he watches everybody else sitting to get a few goodies and he has to wait his turn, it might spur his appetite a bit. It's the best way I've found to get everyone here, Riley included, to take medication.
As for the treat wrap itself, have you tried the Laughing Cow little soft cheese triangles? I like them for a number of reasons. They're so small that you don't run the risk of the cheese getting yucky the way larger "treat items" sometimes do. The cheese also seems really slippery and goes down easily for the dogs and I've had remarkably little sucking off of the cheese leaving the medication behind. Once Nora left behind a bit of a HW treatment which I then hid in another bit of laughing cow cheese and she ate it. In contrast, virtually all the other cheeses and livR sausage I've used has been sucked off medication several times before the medication goes down. (Doesn't happen every time, of course, but it happens significantly more than it has with laughing cow cheese.)
I don't know how many meds he's taking. If the tramadol continues to be a challenge to give him, would they consider trying a different pain med, maybe metacam that could be delivered in a liquid? It's such a small amount for our dogs it helps in dispensing. I don't know if it would be an option for Ernie or not.
I hope he feels better soon. He really got zapped with a lot of things at once, didn't he? Thank you for taking such good care of this poor little guy. I'm looking forward to the day that this is just a memory and we're all marveling at how well he moves and how good he looks and feels!