I have a 13 month working cocker spaniel, he’s only a small little boy, between 7-8kg just before his one year check up which I was told was on the lowest end of a normal weight for his breed. Should I wait a little longer to castrate him or does this not affect his growth? Vets just said any time after 12 months to castrate. He’s fed double what our older dog gets but occasionally you can see his ribs - will castration help him put weight on? TIA