For me, a huge part of the beauty of living with dogs has always been their terrific otherness. With a sense of smell at least a thousand times better than our own (some estimates go up to a million), and an attendant higher allocation of brain real estate to interpret it, dogs nevertheless routinely put this exquisitely sensitive apparatus millimetres from feces in apparent fascination. The world of your dog is far and away a chemical world.

If you get angry or stressed, dogs smell it on you as readily and from as far away as you can smell cinnamon buns baking, if not more so. Our world is colourful. Their vision is less colourful: they see similarly to how someone with red-green colour-blindness sees. It’s also fuzzier, like that of someone who’s lost their glasses, but night-capable and with greater sensitivity to movement. They hear better and over a much broader range than we do, also compatible with an ancestral night-hunting lifestyle. But do they have a sixth sense?

Animal instincts
Sixth senses are well documented in animals. The ones we know about so far are:

Echolocation. A sonar system that gives animals a pinpoint location and descriptive fix on the physical world, this is incredible stuff. Bats can discriminate mosquitoes on the wing with their sonar, and dolphins can discrim-inate complex shapes as well as echolocate “through” objects, for instance “seeing” fish buried in the sand. (It has even been suggested that they can “X-ray” us.) Dogs have not been demonstrated to have sonar, or to possess any of the apparatus for it.

Electric and magnetic field perception. Whereas you and I can of course feel strong electrical currents, only some humans have been shown to have the ability to detect weaker fields, and then only if it is of the AC variety and only if our body hair is not removed, which suggests the mechanism we use is indirect. Basically, we infer the field when our hair moves. Shave it off and we’re oblivious.

Sharks, by contrast, have dedicated organs for detection of magnetic fields, which they use like a compass to navigate, as well as to detect prey (the prey’s muscle contractions give off an itsy-bitsy electrical field). The importance of this perception system in sharks is illustrated by the degree to which it has driven the evolution of the weird head shape of hammerheads. Dogs lack the particular gear, and so their world is akin to ours in this regard. It’s therefore likely that dogs who predict seizures in their owners are responding to a smell or subtle behavioural cue rather than a change in electrical activity in the owner’s brain. It also makes the earth’s magnetic field a somewhat shakier contender for how dogs find their way home over vast distances and novel territory.

Lateral line (pressure detection). This is the system fish use to feel movement. It allows for the fabulously precise, mass-synchronized schooling movements you may have seen on nature shows, and is a related system to the electric-field-detection system. Dogs do not have a lateral line system any more than we do, and so the precision of their tactile discrimination is proportionately worse.

Seismic detection. There are oodles of anecdotal reports of dogs (and other animals) behaving strangely prior to earthquakes. Science so far has come up emp-ty-handed, however, at showing that animals actually do this, or with a convincing mechanism for how they might. (Hypotheses include that they smell gases released early on in ground-shifts, or simply feel the shaking earlier than we do.)

This raises one of the ways science, which copes very nicely with probability theory, clashes with intuition, which doesn’t. Within any large number of people and dogs, it is statistically inevitable that a certain percentage of dogs will happen to bark or do a novel behaviour prior to an earthquake, and happen to be witnessed by a human. To a person, the dog’s behaviour seems uncanny, but this is more testament to our human tendency to connect coincidental events than to a seismic-detection ability in dogs. (Possible interesting exception: elephants.)

Telepathy, clairvoyance, precognition. Again, there is no shortage of stories about dogs with ESP, reading minds or seeming to predict what’s about to happen but again, it has never held up to scientific scrutiny. And, lest you think that science loves raining on these parades, consider that there’d likely be a Nobel Prize and immortality for a scientist who could prove telepathy or precognition in any species, so science is plenty incentivized. The most interesting thing here is how the complete absence of any evidence of paranormal ability (notably in humans) has not slowed down the lucrative psychic industry. We love to believe.

Jacobson’s (vomeronasal) organ. Ah, now we’re getting somewhere! This “other” olfactory system was first discovered and described in snakes, which are the Jacobson gold medalists. Access to the glands involved is available strictly from two holes (pits) in the roof of a snake’s mouth, which is why snakes are said to “smell with their tongues” and also accounts for the forked tongue of snakes and many lizards. The wider the fork and wider the spread between the corresponding pits, the more “stereo” (direction-sensitive) the olfaction, which aids hunting. In mammals with a well-developed vomeronasal system, like lions, its utility is not in hunting but in the receiving and interpreting of pheromones, to assist in mating.

Enter dogs, at last
Dogs have a much, much better developed vomeronasal system than humans have, and humans, in spite of our feebler equipment, have been demonstrated to be pheromone sensitive (especially women!). Interestingly, although the anatomy of the dog vomeronasal system has been well described, there is surprisingly little direct research on exactly what dogs do with it.

The circumstantial case is that they do what other mammals do: decode pheromones via a fast track between the vomeronasal organ and limbic system of the brain. But although male dogs sometimes lick urine, few dogs exhibit much in the way of a Flehmen response (wherein compounds of interest that are less volatile are worked into the roof of the mouth by the characteristic upper lip extension and breath intakes), in contrast to other mammals with comparable equipment.

Synthetic dog lactating pheromones hit the market a few years ago as a behaviour-problem aid, and have been shown in a few research studies to mitigate symptoms in dogs with separation anxiety, as well as barking in shelter dogs. It’s a potentially promising avenue that I hope will be further explored.

By Jean Donaldson
Canadian Jean Donaldson is the founder of the San Francisco SPCA Academy for Dog Trainers. Her books include The Culture Clash, Dogs Are From Neptune and MINE! A Guide to Resource Guarding in Dogs.

(Appeared in October, 2008 issue. To learn more about our print edition click here)