Feeling the spine isn't a big deal. Skinny dogs aren't a big deal, as long as they aren't underweight for their size/age. The easiest way to know if your pet is a healthy weight is during a bath, when all the fluffy fur is soaked down. You should see a 'pinch' in behind the dogs ribs. You should be able to feel the ribs, but not see them.
According to a Vet site I found, "The "ideal" weight for a dog is approximately the weight where the last 3 to 5 ribs are just barely visible or can be felt with a very light touch. Many dogs are overweight and many dog owners feel their dog is too thin if they can see any ribs. It is better from a health perspective to be a little too thin than to be a little too heavy," (
Whats normal for a dog?)
See your vet if you aren't sure.
Dogs and puppies are meant to be lean - not pudgy. Obesity leads to early death, illness, joint pain and injury, heart disease and more. 1 out of every 5 dogs in the USA is obese. Because of this epidemic, most people don't even know what a healthy dog looks like - most are overweight if not obese.
Puppies are skinny because they are growing!!
Please don't 'fatten' your dogs up. At our dog park, the other owners think my dogs are too thin and always make nasty comments. I wouldn't care, except their dogs are all overweight and thats what they think is normal!! ITS NOT!!!