Beau's weight dilemma

by MAM
(Australia)

So my beautiful 6 month old (today!) long coat GSD pup is at the vet today for his 'operation'.

The vet has already told me something I know well - he's underweight. He's VERY active, eats well but can be fussy, gets around 800 gr - 1 kg of large dog puppy growth food a day (plus treats) and weighs in at 33.5kg (which I think is around 74 pounds).

But he's thin and I don't know what to do about it. And I mean really thin - there's no coverage over his ribs/spine at all. He's up to date with worming and vaccinations... I just don't know what to do next. The vet will hopefully have some ideas this afternoon when I collect him (feeling sorry and sore) - in all other respects he's a happy (and utterly gorgeous) boy.

I'd appreciate any ideas from anyone right about now...

Thanks :-)