Welcome to BPO. You will find that there are lots of folks on here who really know their stuff. Why are you concerned about his weight? Has your vet mentioned that he is underweight, too thin, not filling out, etc.? Have you spoken to his breeder? I was concerned about my IW, Max's weight, because he didn't seem to be filling out like I thought he should. His weight will remain the same for a month or so at a time, but then he will suddenly start eating like a horse and gain a few pounds a week, then level off again. The more he plays hard and runs with Jake, the more he seems to fill out. I still think he is too thin, but he is only 18 months old, so I am trying to be patient and let him gradually thicken and muscle up. We got our Pyr, Jake when he was 15 months old and only weighed 74 lbs. He was a bag of bones, or he looked and felt like it to me. He has gradually gained up to 98 lbs. in 7 months and is still slowly gaining. I would just give him time as long as he is healthy and eating well.
Kathy