Agree w/what Mikety T says below. you can see from Worm's pics he's pretty skinny and is 36 lbs at almost 1 year old. pre-neutering, he was quite skinny w/ribs sticking out, but even then, got mixed rxns. most people we met thought he was too skinny. but his vet Dr. D did not and was not worried about it, saying that bassets in general tend to carry too much weight. but then she was away once and we saw a different vet-- he was VERY concerned about it, and made us come back in a month to make sure he put on weight.
post-neutering, his ribs don't stick out that much anymore. he currently looks like he does in the Fort Funston pics. the vets aren't worried about his weight anymore. the last time at the vet's couple weeks ago, the head vet (~20 vets in this practice) walked by Worm and said that everyone will tell me he's too skinny, but don't listen to them, he's not. I should keep him exactly where it's at for the rest of his life...! (personally, i think it'll be harderto do that when he gets older. i'm convinced he's in his teenage svelte years right now. i guess that's coming from the perspective of having a weenie dog that was even skinnier than Worm is now as a puppy! i kept getting 'feed him, feed him!' but by the time he was 3-5 yrs old, he was already on the overweight side... and it was hard for him to lose weight.)
so wanted to tell u this since Jersey & Worm look like they have similar body types right now... anyway, of course, best to get the advice of your vet...
there are many bassets out their that are overweight at 40 lbs,. besure the dog is actual underweight before embarking on a weight adding program In most cases it is the perception of what an Ideal basset should look like that is skew which is one reason why basset tend to be more overweight than the average breed.