Dog urine in carpet of rental?

We just moved into a house were there is copious amounts of dog urine in the carpet. We informed our landlord and after a battle he agreed to have the carpets steam cleaned. The cleaner used a little enzymatic spray but the urine came back up. Now he won't have the carpets cleaned again because he says he made an effort and our standards are too high. I feel we are living in unsanitary conditions. Does he have to get it completely clean or is making an "effort" all he's legally obligated to do? I tried to look up tenant laws but they are so vague as to be unhelpful.