You can purchase a scotch guard spray-on protectant. The one I have used most often is mixed with hot water and applied with my steam cleaner. You could also consider having your carpets professionally cleaned and pay the cleaning company to apply a similar product. I would also recommend you look into a product called Kids 'N' Pets. It is the best stain and odor remover I've found.

www.kidsnpetsbrand.com/