my saint bernard has not been a regular eater since small. He's 2 now and eats every fourth day. I've had x-rays, bloodwork which showed bun slightly elavated. Looks at the food and lays down. I cook him hamburger, liver cottage cheese or yogurt. Hand him something you eat, he jumps on it. I cook for this dog and nothing...

I think Saint Benards tend to be over weight. I cover picky, over weight dogs in the sticky at https://www.askmehelpdesk.com/dogs/information-articles-our-dogs-expert-labman-53153.html#post254171