Hunchback, osteoporosis or just old?

My cockapoo is 17...yes that would be 119 in dog years. (Technically he was born in October, so he's 120 since a dog gets '1 year older' every 52 days. Anyways...) My wife has commented several times lately that it looks like his back is getting more 'hunched' or bowed up. Is this a particular ailment or a common effect of aging? Do dogs shrink like people (the vertebra becoming compact with age from gravity)? Is there any insight into why a dog's back might become more prominently arched or could my wife be imagining things.

My old dogs hunch if they are cold or in pain. I would recommend a trip to the vet.

My old boy had a hunched back, he had Spondylosis, maybe a visit to the vet is in order.