My Springer spaniel will be 2 this month. He is fairly active and eats well, however he is quite thin. You can see the outline of his ribs although they do not blatantly stick out. Both his parents were sleek dogs, is this normal or should I be worried? He was wormed approximately 4 weeks ago

Pammi, labman likes to use this link for owners to evaluate their dogs.

http://www.puppychow.com/products/popup_body_condition.aspx

In general dogs ribs should be outlined and they should have a "waist".

That being said, healthy springer spaniels have a tendency to be sleek with a rather protruding rib section. My brother has one. I always felt his ribs stuck out a bit too much, but I truly think it is the breed. As he has aged (he is now about 8 years), he has finally started to fill out a bit more and is very healthy looking. He still acts like a silly puppy. If you are at all concerned, please bring your dog in to see your vet for an evaluation. Discuss the type and amount of food you are giving him, and his activity level. Your vet should be able to advise you as to whether adjustments need to be made. :)

Not a lot more for me to say. Most Labs are terrible gluttons that eat themselves to an early death. Other breeds insist on showing a little rib. Shepherds are notorious for that. If your vet isn't urging you to fatten him up, don't.

It wouldn't hurt to read the sticky on ''My dog won't eat.'', https://www.askmehelpdesk.com/dogs/information-articles-our-dogs-expert-labman-53153.html#post254171

Also with springers there is a difference in weight in comparison to working breeds and pet breeds, if your dog came from working lines he will tend to be sleeker than a pet or show type and this will show...