We have a seven month old male Wire Haired Fox Terrier who, from day one, has been totally indifferent to food. We have an adult Smooth Fox Terrier bitch that wolfs her food down in a matter of seconds – much like any other dog I've owned.
We've tried separating them at feeding times in case there's some competition or anxiety issue. We've experimented with alternate (quality breeder/vet recommended) canned and dry foods, dishes, locations, feeding times etc. etc., but he still requires patience and twenty minutes per feed to eat even the smallest portion. On one occasion we left his food with him for a whole day and by nightfall he hadn't touched it. At six months old we cut his feeds from thrice daily to twice daily. In desperation, I even tried feeding him just the once per day to see if hunger would kick start the process with no success. If one of us doesn't sit with him offering encouragement and occasionally holding the bowl up for him, he will ignore his food and just trot off with his tail in the air. He now hasn't eaten more than two mouthfuls for 72 hours.
He's not eating anything else in between times; he's otherwise fit, happy and healthy. He was de-sexed recently and the vet says he's a good healthy dog. He weighs 9.2 kg.