The Science of Skunks
If you’re a dog owner, you know that dogs are curious creatures and will often stick their noses where they don’t belong. Unfortunately, this can sometimes lead to your pet getting sprayed by a skunk. Skunk spray is not only smelly, but it can also be harmful to your dog.
Chemist Paul Krebaum’s discovery revolutionized the way people deal with skunk spray and became known as the “skunk odor remedy.” It quickly gained popularity, and the mixture is now widely used by pet owners and wildlife rehabilitators to remove skunk odor from animals and other surfaces.
Here’s what you need to know and how to help your dog if they get sprayed by a skunk.
The Striped Skunk (Mephitis mephitis)
The skunk is widely known for the highly odoriferous defensive secretion. Although skunks can be a nuisance when they spray or dig in gardens, they are important members of the ecosystem and play an important role in controlling insect populations.
While the striped skunk (Mephitis mephitis) is widely known for its ability to spray a strong-smelling liquid, this is used as a defense mechanism when it feels threatened. This spray is produced by two glands located on either side of the skunk’s anus, and it contains a mixture of chemicals such as sulfur-containing thiols, which give it a strong, pungent odor.
In addition to their defensive spray, striped skunks are also known for their distinctive black and white striped fur, which are used to direct predators’ eyes straight to the source of the animal’s smelly anal spray. Skunks are found throughout much of North America, from southern Canada to northern Mexico.
- A member of the weasel family (Mustelidae) and is one of several species of skunk found in North America
- Skunks can accurately spray from about 15 ft (4.6 m) away
- The smell from a skunk can spread up to 1 mi (1.6 km) away
- Skunks can spray 5 or 6 times in a row; they don’t spray you just for fun as they need 8 to 10 days to replenish their spray
- Primarily nocturnal, spending days sleeping in dens or other sheltered areas
- Skunks are found in suburban and urban areas
- Are omnivorous
- Their diet includes insects, small mammals, fruits, vegetables, and carrion
- Skunks typically mate in the late winter or early spring, and females give birth to litters of 4 to 7 young in late spring or early summer
- Skunks are beneficial to the environment because they eat insects that can damage crops and gardens
The Chemistry of Skunk Spray
It’s important for dog owners to have a basic understanding of the composition of skunk spray to effectively neutralize it.
For quite some time, scientists have been intrigued by the chemical composition of skunk spray. The chemicals secreted are so obnoxious, that few chemists have been willing to work with them. However, the first report in the chemical literature on skunk spray was in 1862 by the famous German Chemist, Dr. Swarts working with Wöhler in Germany.
In 1879 another German, Dr. O. Löw next reported work on skunk spray. He confirmed Swarts’ findings that it contained sulfur compounds and a nitrogenous base. His major problem in completing the research was not his expertise in chemicals, but the reactions of his companions and co-workers. His experience was reported in a letter,
“On an expedition through Texas in 1872 I had frequent opportunity to collect a sufficient quantity of this secretion to establish its chemical constitution, but all my companions protested against it, declaring the odour which clung to me to be unbearable. On my return to New York City I started a few chemical tests, with the little I had collected, when the whole college rose in revolt, shouting, ‘A skunk, a skunk is here!’ I had to abandon the investigation.”
Next, Thomas Aldrich, working in the Laboratory for Physiological Chemistry at The Johns Hopkins University, investigated skunk secretion and reported his studies in 1896 and 1897.
He described it as follows, “the secretion is a clear, limpid fluid, of golden-yellow or light- amber colour, of a characteristic, penetrating, and most powerful odour, and having a specific gravity, at ordinary temperature, less than water (0.939).”
In 1945, Stevens made a brief foray into the field of skunk research while searching for new animal musks. Stevens noted that the secretion was “repulsive in odor,” which may have kept him from working on it in a timely fashion.
In 1990, William Wood was the next player in skunk spray research.
Analysis of the anal sac secretion of the striped skunk (Mephitis mephitis) demonstrates seven major volatile components.
Dr. William F. Wood Humboldt State University Department of Chemistry:
These can be divided into two major groups of compounds, thiols and acetate derivatives of these thiols. Two of the thiols are responsible for the strongly repellent odor of the secretion, (E )-2-butene-1-thiol and 3-methyl-1-butanethiol. The third thiol, 2-quinoline-methanethiol, is not as odoriferous due to its low volatility and the fact that large thiols do not trigger the human olfactory receptor. The chemical structure of these compounds and their percent (four individuals) in the defensive secretion are shown below:
A second major class of compound in skunk spray are thioacetate derivatives of the three thiols. These compounds are not as odoriferous as the thiols, but are easily converted to the more potent thiols on water hydrolysis. This chemical conversion may be why pets who have previously been sprayed by skunks will again have a faint “skunky” odor on damp evenings.
Thioacetate derivatives of (E )-2-butene-1-thiol and 3-methyl-1-butanethiol trapped in the animal’s hair could be releasing the smelly thiols under the damp conditions. The chemical structure of these thioacetates and their percent in the defensive secretion are shown below:
A third type of compound is found in this secretion, it is the alkaloid 2-methylquinoline. This compound is clearly related to 2quinolinemethanethiol and S-2-quinolinemethyl thioacetate. 2-methylquinoline is perhaps a product in the biosynthesis of these two compounds. The structure and percent of 2-methylquinoline in skunk secretion follows:
Krebaum’s Skunk Odor Neutralizer
The skunk odor neutralizing formula was devised by Paul Krebaum, a chemist employed by Molex, Inc. of Lisle, Illinois. Krebaum’s formula was created as an alternative to tomato juice or tincture of time in helping rid his laboratory of odor while conducting research using chemicals called thiols – some of the nastiest smelling chemicals around. Using basic chemistry knowledge, Krebaum figured out a way to get these foul smelling thiols out of his lab by changing them into other compounds.
*Thiols are a group of organic compounds and are produced by many things, including the degradation of proteins and are responsible for the odors that comes from decomposing flesh and fecal matter. Yuck!
The trick: to have the oxidation-getting oxygen molecules bond with thiols and change them into things that didn’t smell bad at all.
Krebaum naturally knew that sulfur binds quite readily to oxygen molecules to bind thiols, and that these “oxidized” derivatives are far less likely to smell; effectively neutralizing their foul-smelling odor. Experiments showed that an alkaline solution of hydrogen peroxide readily oxidized hydrogen sulfide to odor-free sulfate. The problem of hydrogen sulfide smell in the plant he worked in was solved.
For pets, Paul Krebaum developed one of the best home remedies using an adaptation of his laboratory method used to destroy hydrogen sulfide and thiols. A colleague asked him to help with a pet cat that had been sprayed by a skunk after Krebaum had devised the formula and used it in his laboratory for some time.
“He came in to work and said his cat had an encounter with a skunk,” Krebaum recalled. “He said he had tried tomato juice, and it didn’t work, and the cat still wasn’t able to come into the house.”
Realizing that thiols were at the root of skunk odor, Krebaum modified his laboratory cleaning formula so that it could be used on animals. Krebaum’s colleague reported that the formula worked like a charm, removing every trace of odor from the cat.
“He came back the next day and said the stuff worked like magic, that every trace of skunk odor is completely gone from the cat,” Krebaum said.
The variation Krebaum developed for the cat and that is widely used today is this:
- 1 quart of 3 percent hydrogen peroxide
- 1/4 cup of baking soda
- 1 teaspoon of liquid soap, which breaks up the oils in skunk spray and allows the other ingredients in the solution to do their stuff.
The solution should be rinsed off the pet with tap water.
This remedy is effective as chemist Paul Krebaum’s solution changes the odorous thiols into odorless acids, thereby chemically neutralizing the skunk odor.
Old Wives’ Tales
Despite popular belief, tomato juice is not a suitable solution for this task; vinegar is also ineffective in neutralizing skunk odor.
Bathing an animal in tomato juice is a popular home remedy for eliminating skunk odor, and one theory suggests that it works because of a phenomenon known as olfactory fatigue. At high doses of skunk spray, the human nose may stop smelling the odor, which allows the scent of tomato juice to become more noticeable. When a person experiences olfactory fatigue to skunk spray, they may believe that the tomato juice has neutralized the odor, even though it has not. This can be confirmed by another person who has not experienced olfactory fatigue and can still detect the skunk spray odor.
In October 1993, Chemical and Engineering News published Krebaum’s formula.
Sadly, Krebaum’s formula will never bring riches to its inventor, for the solution is trapped within a cruel chemical Catch-22:
“Once you mix the hydrogen peroxide with the baking soda, it is no longer stable,” said Krebaum. “You can’t store it in a bottle, because it would explode from all the oxygen.”
Due to packaging and transportation difficulties associated with the ingredients, Krebaum decided against trying to patent his formula and subsequently placed it in the public domain. The formula was then published in the October 1993 edition of Chemical and Engineering News.
In Krebaum’s formula, the soap functions to disperse and break up the oils in the skunk spray. This then allows the other ingredients to neutralize the thiols in the skunk spray.
Combine the ingredients at the time of use. This solution works to remove skunk odor because of a chemical reaction initiated immediately upon combining the ingredients. If it sits for too long, it will become ineffective.
- 1 quart of 3% hydrogen peroxide
- 1/4 cup baking soda
- 1 teaspoon dish soap
*Treat First, Rinse Later:
Skunk spray is a yellow oil that adheres to most surfaces it comes in contact with. As an oil, it does not mix with water. The unpleasant smell of skunk spray is due to as many as seven different volatile compounds present in it, which are primarily thiols or thioacetates. Thiols are notorious for their strong and quick binding to skin proteins.
Although thioacetates are usually less odorous than thiols, they can transform into thiols when they come in contact with water. This is why the smell of skunk spray intensifies when the sprayed animal becomes wet.
- Mix the ingredients together in a large bowl.
- The mixture will start to bubble and fizz, so be sure to mix it in a well-ventilated area
- Apply the mixture to your dog’s coat, avoiding the eyes and ears
- Let the mixture sit on your dog’s coat for 5-10 minutes
- Rinse your dog thoroughly with warm water
- Repeat the process if necessary
Effects of Skunk Spray
Commonly noted in animals that have been sprayed by a skunk:
- Ocular edema
- Rub their faces
- Temporary blindness may occur
- Inhalation can occur if an animal is sprayed directly in the face
In rare instances:
- Heinz body anemia
If your pet has been sprayed heavily in the face:
- Flush the animal’s eyes with tepid water.
- If an animal has received a heavy spray or multiple exposures, obtain baseline blood work from your veterinarian.
- Skunks are also vectors of rabies. If your pet is bitten by a skunk, report the case to the proper authorities.
Unfortunately, dogs frequently come across skunks during the late evening or at night when stores and veterinary clinics are closed, which can make it difficult to obtain the necessary products to address the problem promptly.
Consider Krebaum’s formula first, though there are a variety of odor control products available you can keep on hand that have good reputation of success.
Pet & Property Deoderizing Products
Recommendation by the U.S. Department of Agriculture is to use over-the-counter products that contain neutroleum alpha®. This includes:
While skunk encounters can be unpleasant for both pets and their owners, it’s good to know that there are effective solutions available to address skunk odors. The key is to act quickly and use the right products to neutralize the odor and prevent it from lingering. By understanding the science behind skunk spray and odor removal, pet owners can take the necessary steps to keep their dogs smelling fresh and clean, even after a run-in with a skunk. Whether using a commercial product or a DIY solution, the most important thing is to be prepared and to have the right tools on hand. With a little knowledge and preparation, pet owners can tackle skunk odors and keep their furry friends happy and odor-free.
Sheepdog Riggs, Forever in Our hearts
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