That's awesome…I'm glad the pupper is okay. I have to renew my Pet First Aid Certification. It only lasts a couple years...and then you have to retake the class. I guess that's something I'm going to have to look around Denver-area for.
I have a noneater…. when she gets to the ribby stage, I force feed her. No amount of additives... not cream cheese, not canned food, not real food, interest her. Even with barf dinners she will eat a little some days and leave the rest. Fortunately she lets me put a spoon in her mouth and swallows but it is a pain. We have had every test known to man including full thyroids run... she simply doesn't care about food. She will eat "treats" but not any that could healthily be her main food source.
That said, free feeding is usually not a good idea and especially not with overweight or underweight dogs. Setting meal times and taking food up is a biggie. The gravy stuff might be good, depends on what it is. Most I have seen are pretty icky ingredients. Adding in something simply like a couple of tbs of olive oil can give some good calorie boosts. The other thing is that if hte treats you give aren't higher calorie than the regular food, your treats may in reality be contributing to weight loss as they fill up but don't add weight. A good rule of thumb for a thin dog is at least 19 percent fat content. Its a lot easier to feed a dog a higher fat than more volumn of a lower fat food (ie 1/2 cut high fat compared to 1 cp of lower fat).
I post the following link while knowing that there are exceptions. Sayblee will nearly starve herself to death, and certainly down to unhealthy (backbone showing) weight. There are meds (crypoheptadine) to help eat more, btw, but as long as she willingly lets me feed her, I am putting it off.
I have him on a higher fat/calorie puppy food and have been feeding more treats (checked to make sure they were also high in fat and calories) and he is not so ribby anymore. In fact he is doing quite well. We are on an eating schedule of some sorts in the fact that he eats at night twice even though I leave it out still. but we have a routine that is working and keeping him healthy looking.
I was just about to add a post, when I had to leave and pick the kids up from school - saying that my Basenji did a similar thing. It started with her normally soft fur getting really coarse along her backbone. While I didn't notice any more than the usual tiny bit of shedding in the late summer months, it is now back to it's normal "super soft puppy like fur" too! Great news!