Puppy wheelchair with extra 'leg' and larger wheels and longer cradle

This is a remix of DIACOV's puppy wheelchair (small).
I changed the wheels (used wheels off another design I had on hand, then laid them 3 thick and increased the size by 125%) I also trimmed, added and thickened the cradle I made it about 3cm longer and doubled the thickness by simply copying it and laying it on top of the old design. I am sure there are better ways of doing it but I am not a designer so this is the best I could come up with.
I added the training wheel part 'extra 2.0' to add the additional wheel to support the puppy because it had trouble balancing and caused some back stress.