1. Dogs don’t enjoy being hugged as much as humans and other primates.
  2. Dogs dream just like human beings. Small dogs actually have more dreams than big dogs.
  3. An African wolf dog known as the Basenji is the only dog in the world that cannot bark
  4. A dog’s mouth exerts 150-200 pounds of pressure per square inch
  5. Obesity is the prominent health problem among dogs
  6. Puppies sleep ninety percent of the day for their first few weeks
  7. A dog’s heart beats up to 120 times per minute, or 50% faster than the average human heartbeat of 80 times per minute
  8. Rin Tin Tin was the first Hollywood dog star
  9. Dogs can be trained to detect epileptic seizures
  10. Spiked dog collars were invented in ancient Greece and were originally designed to protect dogs throats from wolf attacks

Source:

http://www.mirror.co.uk/news/weird-news/dog-facts-10-amazing-things-3908754
http://www.petsworld.in/blog/10-weird-dog-facts-you-wont-believe-are-true.html
http://www.petmd.com/dog/pet_lover/WW_5unusualdogfacts
http://www.cesar.com/live-the-life/just-for-fun/100-weird-facts-about-dogs.aspx