My wife and I were walking our dog at about 8 pm in early May, well before it was dark.  To our surprise we noted a large skunk foraging for food on the lawn of a neighbour.  Fortunately, our dog was leashed and we were across the street, so we were in no danger of the “lethal” defensive spray of that infamous animal.

There are 10 species of skunks in diverse places around the world and apparently all of them possess a special gland that can release their spray in a range of 1 to 4 meters, so keep your distance when such an animal has his/her back to you.

This sighting reminded me of the discovery of just what molecules were responsible for the huge respect we all have for Mephitis mephitis, the North American skunk.  It was believed for over one hundred years that essentially one compound caused the intolerable stench that can be detected in a few parts per billion, namely butane thiol.  This is a molecule with four carbon atoms in a row appended to a sulfur atom, in turn bonded to a hydrogen atom – by organic chemistry standards, a simple molecule.

In the early 1980s, a chemist at the University of New Hampshire decided he would check if this early finding was in fact, correct.  He was able to obtain a small sample of the secretion from a skunk farm where the animals are raised, as they are apparently excellent pets as long as they are “descented”.

Using modern separation and characterization techniques (gas chromatography, mass spectrometry, infrared and nuclear magnetic resonance spectroscopy), Anderson discovered over 100 different compounds in the secretion with most of them containing one or more sulfur atoms.  Organosulfur compounds are very diverse in structure and are often quite odourous, they are known to be responsible for the special smell and taste of onions and garlic.

Anderson identified the major molecules of the skunk mix but it was very clear that the original speculation about  butane thiol being the culprit was not correct.  There was an error in the early analysis that missed two hydrogen atoms.  As it turns out, there are five different sulfur-containing molecules that comprise about 90% of the mixture.  Curiously,  most of these molecules are also present in two other species of North American skunks, the spotted and hog-nosed varieties.

If your pet is sprayed, there is an effective method for neutralizing the odour, and it is not by washing the animal with tomato juice.  All that will result from this procedure is that if you have a white dog, you will wind up with a still-stinking, pink one.  The reason that some people cling to this outdated procedure is due to “olfactory fatigue,” where the washer’s sensory mechanism is saturated and no longer perceives the skunk smell.

The proper procedure is to destroy the sulfur compounds by oxidation, whereby the resultant molecules become water soluble and odourless.  The formula is to bathe the animal in about a quart of 3% hydrogen peroxide (obtained at a drug store).  In that mix is a quarter cup of baking soda (sodium bicarbonate) and a teaspoon or so of liquid detergent.  Wash and wait several minutes then rinse and repeat if necessary.  The wash mixture needs to be made fresh each time so have the ingredients available if you live in a vulnerable location and this location can be in as urban an environment as downtown Montreal.  I was startled one early morning on the McGill campus when exiting my car to see a skunk not 6 feet away quietly munching on something.  The slam of the door caused his relatively quick departure.  I stayed in the car until he was long gone.  No matter how you view this interesting but fearless animal, it has to be at a distance.

                                                                                              By Dr. David Harpp

                                                                                              McGill University