Today is National Dog Day, a celebratory day of the year started in 2004 by pet advocate Colleen Paige as a means of encouraging the adoption of pets, as shelters are currently "overrun" and thousands of animals are euthanized each year, CBS News reports. In celebration, here are 5 surprising facts about dogs you probably didn't know!

"Dogs are really doing everything that we wished we could do for each other," Paige told CBS. "They love unconditionally and we really can't love each other unconditionally...we're just not made like that. I think it's such a travesty that dogs are so abused and neglected when they are one of the most wonderful creatures on this earth."

Any dog owner would likely nod in agreement, as animal lovers seem to always be one step ahead of scientists when it comes to an innate understanding of their pooches. But did you know...

1. Obedient dogs live longer lives. If your dog insists of pulling on the leash during walks, eating your food and peeing all over your things, you may have a dominant dog on your hands, and dominance can breed anxiety and resulting bad behavior.

Dogs are pack animals, which means they do best when they know their place in their family hiearchy. In the wild, wolves live according to the rules of strict social structures, and dogs, while domesticated, are not much different. Though his methods and the "dominance theory" are controversial, Cesar Milan recommends making sure your dog knows that you are in charge, and behavior modification is essential to a happy pet.

In fact, docile and obedient dogs are more likely to enjoy longer lives. According to research published in June 2011 in the journal The American Naturalist, scientists discovered that regardless of breed, bold and aggressive dogs tend to die more quickly, while more eager-to-please canines tend to live longer lives.

2. Dogs are as intelligent as 2-year old children. According to 2009 research published by the American Psychological Association, the average dog has the mental abilities of a 2-year old human child. According to canine experts, some of the smartest-ranking breeds are border collies, poodles, Labrador retrievers, Yorkshire terriers, Golden retrievers and German shepherds, all of which possess intelligence on par with a 2.5-year old. Not only can dogs do simple math and solve spatial problems, they are keenly aware of human emotions, and are one of the only mammals that respond to human finger-pointing just as toddlers do. In addition, dogs experience emotions such as anger, jealousy and disgust.

3. Dogs can be trained to sniff out human diseases such as cancer, diabetes and epilepsy. With their adept sense of smell that is 100,000 times better than our own, dogs can not only sniff out bombs and drugs, but diseases like cancer as well, including that of the lungs, breasts, skin, bladder and prostate, smelling abnormal scents given off by damaged cells.

Dogs are increasingly being used as service animals for sufferers of diabetes, as they can be trained to detect the scent of their owner's blood sugar fluctuations (sweet for high blood sugar, acidic for low) and let their owners know before they experience any symptoms. Dogs can even reportedly sense through smell when a human is about to have a seizure up to 45 minutes before it happens, though how they do this is yet unknown.

4. The shape of a dog's face determines its lifespan. Though it may sound strange, the shape of a dog's face is one determinant of how long they might live. While dogs with more wolf-like faces such as German shepherds and Labrador retrievers tend to live longer, dogs with stouter, shorter snouts such as bulldogs and French bulldogs tend to live shorter lives. Why might this be? Dogs with more squashed faces may develop a variety of medical conditions, as they are more likely to get overheated and have breathing problems.  While they can live just as long as their pointy-snouted counterparts, they may need to pay a few more visits to the vet and receive extra care from their owners to stay healthy!

Click here to read some tips on keeping your wrinkly-faced and squash-faced dogs (such as bulldogs) healthy.

5. Baboons keep and raise dogs as pets. It turns out we're not the only primate that's been known to keep dogs as pets! Baboons have been known to kidnap feral puppies in order to keep them as company and act as guard dogs and protectors of their troops and babies. While little research has been recorded on this strange phenomenon, this inter-species relationship has been well-documented on video.

What can you do for your pet to help them celebrate their special day? "Take your dog to the beach, go buy them a new toy, get them groomed," Paige advises. "That always feels really good for a dog who hasn't been bathed in a long time is to get a good bath and a good grooming. Make sure that you are giving the dog in your care proper exercise and proper food. Read up on the newest health care."