You may want to consider spending some money on getting a hygenist or a mold inspector into the home to take spore samples. Pet odors are one thing but if there is something else then you will want to know exactly what it is. Having that report will also give you documentation that will become a material fact for the property. For a few hundred bucks it is worth it.
Also if they are only pet odors then that is great. The best way to get rid of them is new carpet and pad.
