Keep your pants on.
Dogs only sweat from the bottoms of their feet, the only way they can discharge heat is by panting. Dogs and wolves yawn as a sign of contentment.

What are you looking at?
Dogs have about 100 different facial expressions, most of them made with the ears. Unfortunately, the likes of bulldogs and pitbulls only have 10, due to their breeding. Therefore, these dogs easily get misinterpreted by other dogs and often get into fights.

You old dog, you.
One of the worlds oldest breeds of dog is the Saluki. It is thought to have been developed in ancient Mesopotamia around 3000 B.C.

Three Dog Night.
"Three dog night" (attributed to Australian Aborigines) came about because on especially cold nights these nomadic people needed three dogs (dingos, actually) to keep from freezing.

Does something smell?
A dog’s sense of smell is one of the keenest in nature. If a pot of stew was cooking on a stove, a human would smell the stew, while the dog could smell the beef, carrots, peas, potatoes, spices, and all the other individual ingredients in the stew. In fact, if you unfolded and laid out the delicate membranes from inside a dogs nose, the membranes would be larger than the dog itself.

In living technicolor
It was recently discovered that dogs DO see in color, just not as vivid as the color that humans see.

Just beat Leonardo to it.
Two dogs survived the sinking of Titanic, yes that's right, two DOGS survived. They escaped on early lifeboats carrying so few people that no one objected. Miss Margaret Hays of New York brought her Pomeranian with her in lifeboat No. 7, while Henry Sleeper Harper of the publishing family boarded boat No. 3 with his Pekinese, Sun Yat Sen.

Not so Sweet.
Giving dogs chocolate could be fatal for them, because theobromine, an ingredient of chocolate, stimulates the central nervous system and cardiac muscle. About 1.1 kg of milk chocolate or just 146 g of cooking chocolate (which has more theobromine per gram) could kill a 22 kg dog.

I should get out more...
In the original 101 Dalmatians movie, Pongo has 72 spots, Perdita has 68 and each of the puppies has 32.