Filtering the air your dog breathes may be important. Documented airborne cancer-causing chemicals include those from kerosene, coal, car exhaust, household heaters, chemical solvents, paint fumes, and industrial waste. If tobacco is smoked in your home, or if you live near a busy road, air filtration is highly recommended. You might also consider a high quality filter for your air conditioner intake vent. Here are just a few ideas to get you started.