try grating pineapple or courgettes into both dogs' food - this acts as a deterrent - put your dogs on a good quality complete dog food like Eukanuba or similar -Eukanuba has a high digestible ratio of approx 72% which means only 28% comes out the other end. Cheaper dog foods only fill up the dog, they don't give all the required nutrition which makes woofies look elswhere for it. It's cheaper in the long run to feed the best. Work out your dogs' life style -and will assume as they are Boxers they get a high exercise regime so feed according to the manufacturers recommendations. Having said that, look at your dogs and see how they go - maybe increase, decrease a bit - whatevers needed to keep them healthy.