I am on a year lease and the house is currently infested with rodent mites. The landlord never disclosed there was a problem with mice and now everything I own is ruined and the house is unlivable can I break my lease and take him to court for damages?

How long have you lived there? How long have you known about it? In what state is the property located?

You're going to have to give the landlord written notice that there is a pest infestation and give him a reasonable period to remediated. Usually 7 to 10 days is considered reasonable. Then say in the letter that if he does not remediate the situation within that time you will, depending on what your state permits, either have the infestation remediated and deduct the cost from the rent, or consider the landlord to be in default of the lease and the lease is terminated.

The letter should be either handed to him or mailed to him by certified mail and a copy sent by regular mail.

As for small claims court, you can file a lawsuit for the costs for the damage done to your property as a result of the rodent mites but you're going to need to provide proof that the rodent mites caused the damage and that you weren't the cause. If you've lived there for a short time then you're more likely to be successful.