Science - Dogs' wet noses vital for smell

LONDON: Dogs' wet noses often leave their owners wondering what purpose do they serve apart from making a mess of windows and clothes, but now an
American research team has finally found out that they are vital to the extraordinary ability of canines to sniff out anything from cocaine to cancer.

Lead researcher Brent Craven, of the Pennsylvania State University, says that the layer of mucus in a dog's nose helps them pick up scents.

The researcher says that odour molecules must get through a layer of mucus before they reach smell receptors, and some of them are absorbed quicker than others.

He adds that the mucus absorbs some molecules quicker than others, helping to "pre-sort" and identify smells.

During the study, Craven and his colleagues used MRI images of a dog's nasal airways to develop computer models of how air travels.

The researchers observed that different molecules were picked up at different points along the passages.

According to them, the odour molecules were then latched on to by nerve cells, which are much more abundant in dogs than in humans.

It is significant to note here that scientific studies conducted to date have been focused on how receptors pick up different chemicals.

"We've shown that the sorting out of the different odorants before they even get to the receptors is also important," the Telegraph quoted Craven as telling New Scientist magazine.