I adopted two kittens from the local shelter in January. They were not litter-mates, but were born 3 days apart and brought into the shelter around the same time and were sharing a cage at the shelter. They are now 6 months old. They were both the same size and weight when we adopted them. 3 months later the female is 7 pounds, and the male is only 4.8 pounds. He's so tiny compared to her! In just the past month, she gained a pound and a half while he only gained .2 ounces.
It's been over 15 years since I had kittens, so I have no idea what's a normal, healthy weight for kittens. They both had URIs when I brought them home, and it took the male longer and more vet visits to get over it. At his first vet visit, we were told he had a heart murmur, but at the last vet visit, which was about 2 months ago, they didn't hear the murmur. He seems to have a normal appetite. He's definitely not as active as the female when it comes to playing...he prefers to be on a lap getting some love, but he does still play sometimes. So, I guess I'm just wondering if his lack of growth is a reason to take him to the vet to get checked out. What do you think? Am I being overly concerned here?