Our ACD pup is 8-9 months old and weight gain is decelerating. He's now 29.5 lbs and gaining maybe .5 lbs per week at best (in the beginning he was gaining close to 1 lb per week, then it went down to .7 lbs per week). Is now the right time to fix him and not mess with his growth? Our vet said any time after 6 months of age, so that's where I'm reaching out to y'all for advice.