pickey eater

I recently got a Boston terrier he is 8 years old , the original owner said they gave him pedigree can food so we put some in his bowl, he didn't eat it so we went to the store thinking maybe he just doesn't like it and bought Purina one true instincts can food he didn't touch that either . so, we added our other dog's dry food with its gravy train, he didn't touch that either, so we decided to see if he is a picky eater by giving him a piece of ham and he ate that. what's a good dry food for his picky eating habit?