I rescued Tango at 7 months. He had been fed inferior kibble and table scraps as his diet. Not only that, but he'd never eaten from a bowl, he'd just been fed his meals piece by piece through the crate he'd been kept in 24/7. He was underweight, undernourished, and had no idea what to do with normal food/feeding.
As much as I wanted him to eat to fatten him up and get him healthy, I also knew that I was NOT going to be hand-feeding him for the rest of his life, AND I had NO plans to cater to his every whim regarding what food he preferred.
So once he'd been checked out by the vet and the immediate infections and worms he had were gotten under control, and she said it was OK, I started dealing with his food issues. No more hand feeding, no more tempting him to eat with a variety of things. He was going to get a superior quality grainless kibble and limited ingredient treats, period. I knew that a healthy dog will NOT starve themselves. They WILL eat when they get hungry enough. So armed with that piece of wisdom, I began. He was old enough to be fed twice a day, so I first thing in the morning, I put down a bowl of his kibble (dry, no added stuff, no moisteners) and left it down for 15 minutes. He didn't touch it. So I picked it up and didn't try feeding him again till dinner time. He did have a few licks of Nutrical two or three times during the day, because I didn't want him to have any kind of hypoglycemia issues, but other than that, no food. I put a bowl of kibble down again at dinner. He sniffed at it, but still wouldn't eat. OK, took it up again. Offered some more Nutrical mid-evening which he licked off my finger enthusiastically. Next morning, same deal, a bowl of kibble in front of him....he sniffed, walked away, then came back and chowed down, YAY! He ate the whole bowl, and has never had another food issue since!
Of course I was worried when Tango wasn't eating, but I knew it was going to be for the best. I made sure the kibble I offered him each time was fresh, but other than that didn't do anything to make it more appealing. He eats twice a day, 1/8 of a cup of food each time, (he's 3.5 lbs) and is now an enthusiastic and non-picky eater.