You should be able to, somewhat, feel his ribs when you rub your hands on his side.
Here is Boo in his summer cut. I too,
think he looks too thin, but he's actually been at this weight, 10 lbs, for 2 years. I think the way his black marking goes higher in his flank area makes it an optical illusion to make him look thinner. The 2nd pic is him, at the same weight but in all his winter woolie glory.
