Wag This Way
What is that propeller of a tail really trying to tell you? Truthfully, it can signal anything from elation to aggression.

“A lot of trainers will tell you that a truly happy dog will wag his tail in a circle,” says Pryor. “If a dog does that, you should feel very complimented.”

But it can also be a common sign of aggression. “There’s a lot of misunderstanding,” says Dr. Jules Benson, BVSc MRCVS, a veterinarian at the Doylestown Animal Medical Clinic and a member of the Board of Trustees for the Pennsylvania VeterinaryMedical Association (PVMA). “A lot of slow tail wagging is exploratory and often a sign of ‘I’m excited or scared,’ while lateral movements are a sign of indecision. Bouncing up and down? That’s a happy tail.”

As for the direction of a tail wag, well, that all depends on who’s approaching. According to a recent New York Times piece, when dogs feel positive about someone, their tails wag more to the right. When they have negative feelings, the wagging is biased to the left.

Just don’t be surprised if it’s hard to see evidence of this at home. “The degree of the movements was statistically significant but hard to observe,” says Dr. Benson. “The researchers had to rely on stop-motion photography.”

Sensitive Sniff Test
As the old saying goes, the nose knows — especially with pooches.

“Dogs are capable of sniffing everything from drugs to electricity,” says Dr. Michael A. Selmer, DVM, of the Advanced Animal Care Center in Huntington, N.Y. “Recent studies suggest that they may even be capable of detecting human illnesses, like epilepsy and cancer, with their noses.” In fact, when asked to sniff out colon cancer in a recent study, canines were 90 percent accurate or “just below what a colonoscopy is able to do,” adds Dr. Benson.

So what makes Fido such a super sniffer? According to Dr. Selmer, a dog’s olfactory glands are about four times larger than ours, and their brain is about 10 times smaller. “This means that your dog’s brain has 40 times as much of its brain devoted to smell than we do,” he says, adding that a dog’s sense of smell is estimated to be 100,000 times better than his human owner.

Bing: Why dogs sniff everything they see

This is partly why dogs are often attributed psychic powers — but it’s more that their noses know no bounds.

A dog can smell fear — or at least the pheromones that are released when we’re afraid, says Dr. Selmer. “Sniffing chamomile can make your dog calmer, whereas peppermint can make him more excited,” adds Dr. Selmer. “All these things make him one special creature.” (Though be sure to speak with your own vet before  trying any kind of aromatherapy with your dog.)