I have been around Cavaliers my whole life and now own three. The size varies....depending on Mom and Pop. Past that-there are often throwbacks in this breed as they have been with us since the 1400 and breed to other breeds to accentuate certain qualities. I would not worry about a Cavalier that size. Your Vet will tell you if he or she is healthy. I have one adult that weughs 12 pounds., I think he weighed less than yours at that age. Enjoy your Cavalier. They are very special.
My five month old Cav is 9 pounds...they need to eat a lot as puppies! He was 6 pounds when I got him at 16 weeks.
we have a cav that is 17 months and she only weighs around 12 lbs, she was the runt and was tiny when we had her , and people are always saying how small she is. she also has long spindly legs. she has never had a big appetite, but is full of energy all the time. i guess they are like us no 2 are the same !
No, my 5 month only is about 6.5lbs and perfectly healthy! Some Cavalier are just smaller.
I also have a 5 month old female but she weighs 16 lbs and the vet said she's not overweight at all... They are all different depending on the parents. I knew mine would get big since both the mother and father were about 18 - 20 lbs.! As long as she's not underweight and is eating, I'm sure yours is fine...