Worried about my cat's weight (underweight?)

I've been a little concerned about my cat Murphy's weight for awhile now. I took him to a vet for a recent issue that turned out to be a herpes flare-up. The vet seemed unconcerned about his weight but I still wonder if I should try to beef him up. He weighs 8.6 lbs and his twin brother Connor (do cats have twins? He's identical at any rate) is about 10 lbs. When I pet Murphy I can clearly feel his spine, and his hip bones. His flanks are also a little hollow. He also has a rather oily coat.

So as far as diet: All the cats eat dry food, with a can of wet food split among the 3 some nights. Connor doesn't like canned food much, so Murphy usually eats his as well. We free feed, putting out 3 bowls morning and night with a 1/4 cup of dry food in each bowl. Murphy has plenty of energy and regular litter box use. He also drinks plenty of water, and is a strictly indoor cat, unless he is out on a leash or supervised in my parent's yard. I've attached a couple of pictures, but they don't show his shape very well. Any advice? I thought about a possible second opinion, the vet that saw him most recently is a one we've never had before (same practice, different doctor) and he seemed a little dismissive of the weight worry. So I'm not sure what to do.

Has he had a fecal done recently? He could have some kind of parasite issue going on.

If you feel like something is wrong, take him in for a fecal, blood work, and a combo (FIV, FeLV) test if he has not had one done.

I do have some skinny cats who are just naturally lean.... but  there is a difference between skinny and boney... and if he is boney, then something may be wrong.

My vet clinic that I use for pretty much everything has 3 different veterinarians on staff, but I only really like to use one of them. The other two are fine, but not "my" vet. I have brought cats in when my vet was not there and then brought them in again when she was to get her opinion, because I trust her. I really don't like when vets are dismissive about my concerns. Since I am around my cats 24/7, I feel like I know when something isn't right, and since they have spent much less time with my cats they should take my concerns seriously.

I would get a fecal done and also have a senior blood panel done.  He could have something going on medically.  However, he might just be a lean kitty. 

How old is Murphy? And has he been losing weight or has he been at this weight for a while? I would agree with blood tests, particularly a thyroid test.

Thanks for the replies I know the vet did the combo test to rule out leukemia. I don't remember if they did a blood panel as well, I tried to find the invoice just now but couldn't locate it. Murphy just turned two, so he's still young. He's always been a skinny boy, I feel like he may have gotten a little skinnier over the last 6 months, but nothing drastic.

vball91 said:

How old is Murphy? And has he been losing weight or has he been at this weight for a while? I would agree with blood tests, particularly a thyroid test.

Click to expand...

Yes to a thyroid test.  Beautiful cat!

Update: Murphy dropped down to 8.2 at his lowest, the beginning of June. He has been diagnosed with Idiopathic Hypercalcemia, which menas his body is absorbing too much calcium. He has crystals in his urine but hasn't developed kidney stones. All 3 cats have been on the k/d Science Diet (kidney health diet) since the beginning of June, when our eldest cat had kidney numbers that were a little high. Murphy has gained back 5 oz since the beginning of the month, which the vet attributes to the kidney diet. So Murphy is getting switched to a canned diet only. Not sure how to swing that with the other two eating dry :/