[Nancy]

If he'es fairly new to a wheel, I'm 99% certain it's from a foot. Look closely between his outer two toes and see if there is any pinker areas. Often that is where they bleed from and it is just about impossible to see.

Wash his feet and keep his wheel out for the night.

 

[Nancy]

Usually they fall out because the wheel is on too much of a downward angle. Try tilting it back slightly and see if that helps. Ideally, the wheel should be just about level with a very slight downward angle, just enough that the urine will run off.

 

[Nancy]

I don't thing the treads would cause bloody feet but I am not a fan of anything sticking to the wheel because of the possibility of it starting to lift. Some of the glues used on those sticky things will stick anything and I'd worry about it sticking to a little foot. Also, sometimes the glue is on the edges as well. Doesn't look to be the case with those treads but for some it is.