Dog not getting enough food?

I am boarding an 11 year old Shetland Sheepdog. His owner sent over baggies of portioned food for each of his meals. He gets half a cup of kibble in the AM and PM. He eats that in about one bite in about a second and begs for more. He seems to be starving. He is constantly barking and whining wanting food. He has some skin condition and hair is thin. She said they have tested him for everything and they can't figure out what is wrong with him. I think he is not getting enough protein/food. She hasn't asked my opinion, so I haven't said anything, but it seems he really needs bigger proportions of food each day. What would you do?