I'm not sure about supplements for sure, but sometimes I think a lot of that stuff is overkill. Spending money for very little or no benefit. I can tell you that we gave fish oil and digestive enzymes for a while...and didn't see any difference in the coat or the poop. So we stopped.
I don't think any of those things would hurt...but you're also not probably going to prevent huge genetic diseases by giving those things. I'd actually worry about overloading the dog's system with vitamins more than not giving them enough. Giving too many vitamins isn't such a great thing either.
CD RE TC HIC 7/10