Dogs have an incredible sense of smell — they have more than 300 million olfactory receptors in their nose, compared to our 6 million receptors. This sense of smell allows trained dogs to detect a wide variety of odors, including ovarian cancer VOCs in blood samples, up to 100,000 times better than the human nose can. 4. Nasal polyps. Polyps are noncancerous growths that form in the nose, usually as a result of chronic inflammation (say, asthma, allergies, infections). “In addition to nasal obstruction and. Tumors; Nasal polyps; Nasal deformity ; In addition, the olfactory pathways, which send messages between the nasal passages and the brain, can become impaired from age and from certain medications. Also, certain medical conditions can dull or diminish the sense of smell. These include: Alzheimer’s disease; Brain aneurysm Brain surgery Cancer.