Incisive Papilla in Dogs

Noticing a small growth on the roof of a dog’s mouth has sent many a pet owner rushing to the vet. Any lump or bump should be professionally examined, especially if it appears suddenly. Growths in the mouth are often hard to spot. There's one, however, that's been there since birth.

By definition, the incisive papilla is a projection, or small fold of mucous membrane, located at the anterior end of the hard palate incisors. In other words, it’s on the roof of a dog’s mouth in the middle behind his front teeth. It develops during the embryo stage, and it’s perfectly normal. It’s an extra olfactory organ, or chamber, called the vomeronasal organ. It has fluid-filled sacs that open into the mouth or the nose. It’s also known as Jacobson’s organ.

The scent receptors (nerve cells) in the vomeronasal organ are anatomically different than those in the nasal cavity. The nasal cavity is line with cilia covered with mucus. Receptor cells in the vomeronasal organ usually lack cilia. Instead, they have a large number of tiny projections known as microvilli. These send impulses to the part of the brain associated with sexual and social behaviors. It’s believed this organ plays in important role in a dog’s ability to detect pheromones or other body scents.

A dog’s sense of smell is his primary sense, and it's far more acute than humans. Dogs have more than 200 million olfactory receptors, where as humans have about 5 million. When a dog sniffs he is maximizing his detection of odors. Inhaled air is forced into a nasal pocket where odor molecules accumulate. The more he sniffs, the more molecules gather. As these molecules are absorbed, nerve impulses transmit information to the highly developed olfactory lobe of his brain.

Many people owe their lives to a dog’s sense of smell and that little Jacobson's organ. Dogs are used by rescue crews to find people who are missing, or trapped during disasters. They’re used to locate bombs or contraband.

They even help save the creatures of our oceans. Some dogs have been trained to find whale feces. Since researchers can’t test whales in the wild, their feces give them information about diet, genetics and level of toxins. With dogs on board one research group has gone from finding five samples in two weeks to about 12 samples a day.