Dog

The dog is small mammal in the order Carnivora native to Earth. Dogs were domesticated from wolves relatively recently by the humans. Over time, the dog has developed into hundreds of breeds with a great degree of variation. For example, heights at the withers range from just a few inches to roughly three feet, and colours range from white to black, with reds, grays, and browns occurring in a tremendous variation of patterns. Dogs, like humans, are highly social creatures, which accounts for their trainability, playfulness and ability to fit into human households.

It is also to be noted that dogs are quite fond of wearing hats, especially Sherlock Holmes-esque ones or little top hats. The Tenth Doctor was a big fan of these hat wearing canines, which he often expressed to Martha Jones, Dalek Caan, the Master, and Captain Jack Harkness, especially in the End of Time when everyone else thought insane things like Alonso and Jack getting together and Martha marrying Mickey were happening. --[If you saw this obviously incorrect version of the End of Time, something is wrong with your television set; You should go see a televiion repair man about that, really,]

Notes

• K-9 was made in the form of a dog, but was given advanced technology and human level intelligence. (DW: The Invisible Enemy)
• A type of dog is found on Barcelona. The only known difference between them and Earth dogs is their lack of noses. (The standard joke, which the Ninth Doctor references, is "But how do they smell?"--to which the answer is "Terrible!") (DW: The Parting of the Ways)
• Rose was a small female dog that belonged to Jackie and Pete Tyler in an alternate version of Earth, referred to as "Pete's World" by the Doctor. Rose represented the alternate version of Rose Tyler - the daughter of Jackie and the deceased Pete Tyler in the Doctor's native universe. (DW: Rise of the Cybermen)
• The dog Teazel was captured by Zygons and the warlod Brelarn used his Body Print, as dogs can go where they like. (NSA: Sting of the Zygons)
• During their time in Victorian England the Cybermen created a minion race known as Cybershades which were created using the brains of cats and DOGS.