Is there anyway to get pet smells, dander, etc out of carpets?

the house we are renting has older carpets and the previous renters had pets...i believe both dogs and cats. The odor is horrible when we put the humidifier on in my 2 year old daughters room when she is congested. Is there anyway to get rid of these smells? We had the carpet professionally cleaned and the owner said he won't change the carpets.