Visiting Veterinarian

The power and peril of scents

By Michele Gerhard Jasny V.M.D. - November 9, 2006

There's a particular aroma that evokes for me my grandparents' apartment building in Brooklyn in the 1950s... the smell of kosher chickens, feet and all, simmering in soup pots, onions frying on stoves, combined with a hint of city grime and musty carpet. My grandfather was the "super" there. I think the entire building was inhabited by Russian Jewish immigrants and the same foods cooked behind every door. The odors permeated the whole building. When I smell that smell, I suddenly feel five years old. I can vividly picture Grandpa George clanging shut the heavy metal grate of the old-fashioned elevator. I can hear my grandmother calling me "Missy," a name no one else has ever used for me. I was never sure if it was Grandma's diminutive for Michelle, or if she called every little girl "Missy" in her heavy Eastern European accent.

It's no secret that odors can stimulate different moods and feelings and trigger memories in people. It makes sense when you think about the anatomy. Mammalian noses are lined with chemoreceptors that send information through the olfactory tract to the olfactory bulbs where they synapse with secondary neurons. The axons of these neurons then project to some of the most primitive portions of the brain, notably the limbic system. For those of you who are a little weak on neurology, the limbic system is connected with emotions and many types of behavior, including aggression and sexuality. So even if the idea of aromatherapy might at first seem less than scientific to the hard-core rationalists among us, there really is a good neuroanatomical basis for the theory.

The use of aromatic plants, fragrant oils, and spices for therapeutic purposes has been around for thousands of years. The actual term "aromatherapy" was coined in England in 1937 by a man named Gattefosse, who published a book on the subject. Aromatherapy generally uses volatile essential oils derived from plants. The oils may come from flowers, buds, fruit, peel, leaves, bark, wood, or seeds. They can be prepared from the plant by using steam distillation, solvent extraction, or pressing. The resultant oils are then administered by diffusion, nebulization, massage, or other topical application. Very rarely essential oils are given orally. Burning aromatic plants to produce scented smoke has also been used in both traditional human and veterinary practice. In the text "Complementary and Alternative Veterinary Medicine" the authors report that in Sri Lanka elephants are frequently wrapped in mats or gunny bags and then fumigated with aromatic plant smoke to treat everything from indigestion to constipation. Is there any scientific support for such therapies? Well, somebody actually decided to test out a specific aromatherapy.

Soothing travel stress

An article entitled "Aromatherapy for travel-induced excitement in dogs" by Deborah L. Wells, PhD. was published in the Sept. 15, 2006, issue of the Journal of the American Veterinary Medical Association (JAVMA.) Thirty-two dogs had been referred to the Canine Behavior Centre at Queen's University Belfast in Northern Ireland for "unruly behavior in the car." For this study, the researchers focused exclusively on dogs whose behavior suggested over-excitement caused by anticipation of going to a familiar place where they could exercise. They eliminated dogs who had generalized problems with anxiety, fear of riding in the car, or motion sickness. The hypothesis? That the smell of lavender could calm these hyped up pups on the way to their walkies.

How'd they do it? For six days the dogs were driven along the same roads, at the same time of day, with the same driver, to the same destination in cars fitted with automatic video cameras. The dogs and their chauffeurs were filmed en route to their fun-filled destinations. On half of those days a lavender-impregnated cloth was draped over the seat half an hour before the dog got in the car and left in place throughout the trip. On the other three days, a plain, unscented cloth was placed in the car. When the videotapes were analyzed, lo and behold, they found that the dogs that had the lavender-scented cloth spent significantly less time moving and vocalizing and more time sitting and resting! The lavender appeared to have a calming effect on the dogs.

Of course, there are other possible explanations. Perhaps the scent of lavender was not so much calming as distracting, acting as a form of "environmental enrichment." In other words, you could have put a cloth soaked in sardines, or motor oil, and the dogs might have been equally subdued because they were simply paying more attention to the presence of a strong new odor than to anticipating their walk. Another possibility is that the lavender soothed the human drivers, not the dogs. The dog may then have responded to their chauffeurs' increased mellowness by chilling out themselves. In fact, the owners did report that they felt less anxious during the trips with the lavender-scented cloth. Although further studies would be needed to tease out the variables, another study done at a rescue shelter supported the idea that lavender scent can be calming to canines. It certainly can't hurt to dab a little lavender oil in the car.

Safety first

Or can it? That takes us to another consideration - the misconception that all essential oils are essentially harmless. Essential oils contain compounds that can be rapidly absorbed through the skin and mucous membranes. Just because they are plant-derived doesn't mean they aren't potent. Essential oils can and have hurt animals and people. There are reported cases of children experiencing respiratory failure after having menthol applied to their nostrils or being exposed to other mint oils.

In 1992 JAVMA published the case of a dog that died two days after being treated for fleas with pennyroyal oil. Pennyroyal toxicosis was determined to be the cause of death. Cats and birds are particularly at risk for adverse effects. Specialists advise not to use essential oils anywhere near birds and to avoid incense and room deodorizers as well. There are several reports of birds dying after exposure to frankincense. Cats lack a specific liver enzyme needed to detoxify many substances, including a lot of essential oils. The use of essential oils on cats can be lethal! I once saw a cat slough the skin on its forehead after the owner applied a dab of pennyroyal oil. Even inhalation of the scent may be unsafe in some cases.

I have some clove oil I like to dab around the house when cleaning. One day the house was particularly odiferous, my vet practice being contiguous with my living room. I think it might have been tom cat urine, or maybe some dog with explosive diarrhea. Any way, it stank, and the kids were complaining vociferously. I remembered the old trick we used in anatomy and pathology labs at school when dissecting a particularly ripe specimen - a dab of Vicks vapor-rub under our noses, or a dash of perfume on a surgical mask. I grabbed the clove oil bottle that was nearby and dabbed a teensy amount right below everyone's nose. For a few minutes the lovely scent of cloves filled my nostrils, then my lip began to tingle, then to burn. Soon the kids were crying and I was frantically washing the clove oil off of everyone's face. The discomfort, albeit mild, lasted for several hours. I learned my lesson.

You learn from me. You may put a lavender-scented cloth in the car for the dog. You may cook chicken soup. Other types of aromatherapy may actually have scientific validity, but check with your veterinarian about safety first.