
I too was told by judges that my male dachsie was too lean[ they are still weighed at each show] fellow breeder/show folk had been looking at him before going into the ring and they didn't see a problem when I asked them afterwards, I have tried all sorts to get his weight up and stay there[ satin balls and various high calorie kibbles] and nothing has worked, fellow dachsie owners are envious because they have the opposite problem, I have spoken to several nutritionist at dog food companies and they had never come across a dachsie which had his problem.
He was 3 yrs old at Xmas and I keep hoping that as he matures he will gain weight and maintain it, he has been checked out by the vet who has found nothing wrong and tell me better too lean than too fat, doesn't help when he is my first home bred show dog.
I hope you find a solution to your dogs problem as I know how disheartening it can be.