What are the reasons for dogs to sigh?

You see the family woofers lying listlessly, resting their heads feebly on their two front paws, and sighing. Why? Because it's feeling hard? Satisfied? Or is it dissatisfied with its woof life?

The reason for this could be any of the above possibilities. The American Kennel Club (AFC) says it depends on environmental factors.

"If his eyes are half-closed when he sighs, it means pleasure; if they're open, it means dissatisfaction: 'I don't think you want to play with me.'"

Oops. Doesn't that feel a little guilty?

A dog's sigh is "a simple signal to end a current emotional state," writes Dr. Stanley Coren in his book, "a foolproof tutorial for understanding woofers."

"If you've ever rewarded him for some behavior, a sigh is a sign of satisfaction. Otherwise, it means it's given up on a futile attempt."

So if you and your dog have just had a good time playing or taking a walk in the park together, this sigh means "this woof is so satisfied, now it's time to take a break." If your dog is beside you begging you to play with him without reciprocation, that sigh means, "Uh, I'd better give up, I'm sad."

Dog trainer Pat Engel agrees.

"My own as yet unscientific observation is that dogs often sigh at rest, what I call 'heavy sighs,'" she wrote in the San Francisco Chronicle, "and these sighs seem to be a psychological signal that puts them into a deeper state of rest."

If you think your dog is sighing (or, say, yawning, or making other noises), it's worth mentioning to your veterinarian, Engel suggests. Behind those noises, health risks may be lurking.

If it's not a health reason, it's time to pay attention to the message your dog is sending.

To understand what dogs are saying, reading their body language is key, says Jody Epstein, a dog trainer in Massachusetts, USA.

"If their body is relaxed in bed, their ears are floppy, their head is down on the bed, they are in what we call a 'sleeping' position, and their body is in good condition, then we consider that to be an excellent state of relaxation," she writes in her comprehensive Expert Advice column, "If the dog is lying down but sits up and looks at you and then makes a sound, then it's more likely a communication signal that you need to pay attention."

That signal is something like, "Hey ...... sidekick over there, is it time to play? Remember the last time we went to play ball together?"

Does a sigh always mean a lament?

"Dogs can send and receive a variety of acoustic signals, and they express different meanings depending on different factors (such as environment, experience, intercanine relationships, individual dog differences, etc.)," said Katerina Jones, a senior animal behaviorist and dog trainer in Warwick, Rhode Island, "that in humans: one person's sigh over something may be a bark, a lament, a moan or a whine in another person."

And, Jones adds, certain kinds of dogs may make more different sounds than others.

"The most important thing to remember is that there is never a single answer. Don't force human feelings on your dog!" She says, "Analyze why your dog is sighing in context, and then take note and try to see if you can understand why it's your dog that's sighing because it's more important than analyzing why the dog is sighing."

Indeed, we don't always know what our dogs are trying to say, but that doesn't mean we should stop trying.

The American Kennel Club notes, "Why do dogs make noises? They may be intentional or unintentional, and they all have some specific meaning. Just because we can't understand the various sounds dogs make, don't assume they aren't doing their best to communicate with us."