Is my rabbit too thin?

Question
QUESTION: I have two rabbits - both male and neutered (about 1-2 mths ago). They are brothers and are 6 mth old. Both of them are eating properly (pellets, fresh grass, hay and a few bits of fresh parsley), drinking properly and going to the toilet properly. However, one is what I would call a healthy size rabbit and the other is very skinny. They have both just gone through their moult and their fur is lovely. The skinny bunny has clear eyes, clear ears and no nasal discharge. He is very very nervous though and is constantly on edge (unlike his brother). I don't let his brother bully him away from his food either - I have been watching their eating habits for a while and he certainly munches. There is just me in the house and I am very quiet. I don't try and pick him up or bother him but let him come to me - he likes to nudge me and climb on me. I can't feel any lumps or bumps when he lets me stroke him apart from his bones. He is walking/hopping etc fine. He's just very thin. Not emaciated but you can see his leg bones (not his ribs or anything#. I want to take him to the vets but I don't want to stress him out by taking him in the car.
When they were neutered I asked the vet to check their teeth and she confirmed they were fine. He is certainly eating - he likes to chew - and they have willow sticks #from the pet shop) and loads of bunny chew toys.
Could it be that he is just burning off calories with his nervous energy? Is there anything I can do to help him beef up a little/make him less nervous. I don't understand - out of the pair of them he is the most inquisitive and loves to explore. I am very careful to check that there is nothing in the house that they could hurt themselves on.
I think that's every thing - thank you very much in anticipation of your help.

ANSWER: Hi

Call the vet and ask if they checked for internal parasites while you were there.  If they didn't see if you can bring in a stool sample for exam.  Internal parasites can cause a rabbit to lose flesh condition.

If the rabbit has bony prominence over its side or on its ribs then it is to skinny.  If it has a nice flesh condition over its spine then it is not to skinny.  If it is you can try increasing the feed however they are usually to skinny for a reason.  Whether it be that they are not getting enough food or they have internal parasites or a hidden illness.  Without seeing the bunny I can't tell you for sure. I do know that very active rabbits tend to need a little more feed.

My suspicion would be that he is burning a lot of calories. Nervous rabbits tend to pace and they can burn calories much quicker.  However like I stated since you can feel the bones on the spine he really needs a check-up.  If the stool sample comes back inconclusive then I would take him for a check-up.

Good luck

Pam

---------- FOLLOW-UP ----------

QUESTION: Sorry I just thought - if it is an internal parasite would the other bunny have it too/ alredy be infected? I guess what I'm asking is whether it is infectious to the other bunny? Thanks (apologies for the multiple questions)

Answer
If it is something like pinworms then yes the other rabbit probably has it.  Some rabbits seem to have a higher immune response and don't show symptoms.  You can have one rabbit look completely healthy and the other look sick even if they both have an issue.

Good luck

Pam