has he been checked for worms or thyroid. if he is clear of these conditions then maybe you just need to feed him more. dogs are like people,some are easy keepers and it takes less food to keep weight on and some need more food to maintain weight. you can’t go by what is suggested on food bags.

the spine,ribs and hips should have a thin layer of fat so you can feel the bones but you don’t want the boons sticking out.

He’s probably just very active and is burning all his calories, increase his diet slightly and he will gain some weight. You should be able to feel his back 2 ribs, that is okay any more and he’s too skinny.

feed him puppy food…my dog got worms and she got low in weight and i started feeding her puppy food and it got her back up to a normal weight and now shes very healthy

try feeding him more but before u feed him breakfast and dinner give him a handfull or slightly cooked lambs fry as it helps with appetite

maybe diharea? it makes u loose weight. maybe u need 2 feed her ppl food. nd test 4 diabetes. its pretty common i labz

have him tested for diabetes its common in labs

feed him MEAT
not veggies