I'm going to tell my parents that I think it's wrong to push my dog on a sled.
Why do you think it's wrong to push the dog on a sled?
Because it's not the dog who loves the dog sled, it's me!
Your parents seem to be confused on who to push on the sled, but to tell them how to do it is not really right either. Ask them if they could push both you and the dog on the sled. That way they don't feel dumb and make a lot of commotion about nothing.
What if I really want to ride on the sled by myself?
If the dog really likes it maybe you two can share it. You can take turns and each of you can be pushed on it.