5 Answers

Dogs are no longer 'natural' creatures but have had millenia of deliberate breeding. This causes some brain malfunctions as well as physical ones. It has been noted in humans with some types of brain damage that they will just not recognise parts of their body as being theirs. The same thing is happening with dogs that chase their tail. They do not recognise it as being part of themselves. It can happen with back legs too. Dogs have been known to snarl and snap at their own legs when the leg has tried to scratch its head or neck.

Dogs are still smarter than cats though.

cause they can

Dogs have to learn their tails are attached to their bodies. If they do not learn this we have to have their tails surgically removed so they can learn to fetch. They seek approval and respond to reward with Pavlovian obeisance. Thus dogs will seek out mines and retrieve unexploded hand grenades. Cats by contrast are bored by IQ tests, are in your presence to be entertained and are proud and independent. They will eat only what they like. When you toss a ball they wait while you retrieve it, curious about you next trick. If they lick their paw they are saying that they are more entertaining than you.

They like the smell.

THEY THINK THAT ANOTHER DOG IS ATTACHED TO THEIR BACKSIDE..