Pet odors come from the bodily secretions that interact with bacteria, yeast, and other germs present on the dog’s skin. Urine, feces, and other bodily fluids excreted or released from pets also contain microorganisms that are already beginning to decompose. As these organisms, together with many other chemicals, interact with the air they release gaseous substances that are interpreted by the nose as nasty or very malodorous. Other molecules can interact with these compounds to make the smell worse.
Other causes of pet odors include bad breath, the presence of ear infections, gas formation or the passage of flatus, problems in the pet’s anal glands, and improper diet. Medical conditions such as yeast infections, kidney failure, diabetes, and cancer can also bring about a nasty odor.