We have two rowdy medium size dogs. The current carpet we have is tougher than nails, I think it's Olefin and it's a very low pile loop. Frankly, it's commercial grade and rough! Don't be sliding into 3rd base with this stuff or you'll loose alot of hide. It's held up for 13 yrs and looks new...we just want something a little softer....like most folks have . But, it still has to be durable. So far, Nylon in a low pile or a fiber known as Dupont Sorona Smartstrand (polymer from corn) from Mohawk are the two toughest and the Smartstrand is very stain resistant. Does anyone have experience with Smartstrand?