Interpreting your dog's behaviour

They are all smarter than you think.  Dogs are uniquely tuned in to their human's behaviour.  They are watching you.  If you perform an act repeatedly with a consistent response, the dog will begin to expect the response.  This is delightful if you are training your dog - absolute consistency is the key.  Sometimes they notice a behaviour of yours that ends in a conclusion consistent enough that it makes an impression on them.  Amusingly enough, it has happened that the owner didn't realize how consistent they'd been in this particular behaviour.
Regardless, they are watching you.  Each dog is unique in response.  But, in general, some notes may be made:
by Amy D. Shojai (Subscribe to Amy D. Shojai's posts)
Feb 28th 2011 @ 11:00AM Filed Under: Dogs

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Amy D. Shojai is a certified animal behavior consultant and the award-winning author of 23 pet care books, including "PETiQuette: Solving Behavior Problems in Your Multipet Household" and "Complete Care for Your Aging Dog."

People who love dogs want to understand canine communication. But growls mixed with tail wags can be confusing. Though people rely on words, dog talk combines vocalizations, body language and smells. Here are 12 ways canines communicate.

1. Barking is used during play and defense -- and to get attention. Barks signal conflicted feelings -- "I like you, but I'm not sure," or "I want to play, but I shouldn't." Barking also serves as a canine alarm to alert the dog's family of anything unusual -- a sound, trespassing squirrel or your wearing a hat.

2. Whines, whimpers and yelps are nonthreatening communication. These sounds telegraph fear, pain, submission and sometimes frustration. Dogs also whine and whimper to beg attention or treats from humans.

3. Growls are closed-lipped warnings to keep your distance, and can be soft or loud. Growls are defensive or offensive depending on whether the dog is frightened or hostile. However, growls are also used during play, which can be confusing, though looking at other dog body language can help you know that the growls aren't real.

4. Snarls are growls with teeth displayed and threaten attack.

5. Howls express loneliness and are used to call the family together. Northern breeds like malamutes howl more than other breeds, while some hunting hounds use baying as a joyful variation of the howl.

6. Body positions indicate your dog's emotional state and intent. Confident dogs stand with erect posture, nearly on tiptoe to impress other dogs. Aggressive dogs lean forward, while fearful dogs lean backward. Dogs cry uncle by crouching as low as possible or exposing the tummy. Urinating when crouched before the aggressor is the dog's ultimate sign of deference.

7. Fur is smooth in relaxed dogs. Fluffing the fur along the ridge of his back -- the hackles -- makes a dog look bigger and more impressive. Both fearful and aggressive dogs raise their hackles.

8. Ear position indicates mood. When held high and facing forward, the dog is interested and possibly aggressive. The ears flatten against the head by degrees depending on how fearful or submissive the dog feels.

9. Eyes convey intent. Droopy eyelids indicate pleasure, while alert dogs hold eyes wide open. An unblinking stare is a challenge, while averting the eyes shows canine submission. The pupils of a dog's eyes indicate aggression and imminent attack when they suddenly dilate.

10. Mouths hide or reveal teeth to communicate. Lifting lips vertically to show the canines -- fang teeth -- is a threat that indicates aggression, defense or fear. Lips pulled back horizontally to show more teeth is a submissive grin used to diffuse threat. A flicking tongue signals intent to lick -- an appeasement gesture if aimed at the face. The relaxed, happy dog's mouth is held half open with lolling tongue.

11. Tails beckon you closer or warn away. A relaxed tail curves down and back up in a gentle U, and increased interest makes the tail go higher. Dominant and confident dogs hold their tails high, and wag rapidly in tight, sharp arcs. An aggressive dog signals imminent attack with tail high, often tightly arched over his back with just the end jerking quickly back and forth. A low-held tail indicates submission, and dogs show deference by wagging in loose, wide, low arcs that often include hip wags. A tail tucked between the legs signals submission and fear and is the doggie equivalent of hiding his face, since it prevents butt sniffing from other dogs.

12. Urine marking is used by both male and female dogs, and has social and sexual significance. It takes very little urine to send a pee-mail. Even when he runs out of urine, a dog may continue to lift his leg as a visual signal to any dogs watching.

Understanding canine vocabulary improves your loving relationship with dogs. Pets with curled or missing tails or floppy or cropped ears develop variations on this vocabulary, just like people who speak the same language may have different regional accents.

Amy D. Shojai also appears on Animal Planet's "Cats-101" and "Dogs-101" and lives in North Texas with a senior citizen Siamese and a smart-aleck German shepherd fluent in doggerel. Read her blog on Red Room.
The above constitutes generalizations.  The dog that smiles is wonderfully unique.  The dog that sits and looks at the cookie jar on the counter is delightfully one of a kind.
In conclusion, use the above as starting points.  All dogs learn what works in general with humans and specifically, what works on you.  Dogs have evolved to be a companion to the human, to offer you the type of companionship that you, and you alone, need.  They are a fantastic animal capable of endless variations of communication.  And, be aware.  They are all smarter than you think, yes, all of them.  Enjoy the little cutie at your feet and enjoy that the mental gears are turning, all for you.