My dog does that same sigh you are referring to.
She does it when we won’t play with her, when she’s tired and starting to lay down, and when she is just irritated at us for something.
I’ve noticed two kind of dog sighs…
The first is when they lay down and relax. It’s sort of an aid to relaxation, and it’s more of a forceful puff than a sigh. And it seems like they do it to lower their respiration rate in preparation for a nap.
The second is more like a human sigh. It seems to be an indication that they’re annoyed at something they know they can’t change… sortof a passive-aggressive complaint. It usually occurs in a situation when they can’t get comfortable, or are impatient at waiting, or are patiently tolerating some distraction or nag.
Both are very human behaviors.
I sometimes wonder if dogs adopt human mannerisms, or if they’re common mammalian habits (like yawns or hiccups), or if we’re just anthropomorphising our pets.
Seems to me that many (all?) of the sighing dogs are bigger breeds. Do little dogs not sigh?
AskNott, I would not argue that most mammals sigh. I would, however, say that, at least with what I am hearing here, that dogs don’t just sigh when they are “lying around.” They also sigh when they are dissapointed (as in the case of ZipperJJ’s elmwood’s and mangeorge’s dogs)–places where it would be appropriate for a human to sigh. It just strikes me as too much of a coincidence for it be merely oxygen gathering (as Scarlett67 also implied.
elmwood, good to hear it. I had read your thread about trying to find a place, and I am glad that you are all settling in.
acsenray, that is often when my dog sighs. I hadn’t realized how good of time keepers (or how stuck to scheduals) dogs could be until our current one. You’d think you were torturing the poor critter if you stayed up an extra hour.
ZipperJJ, Perhaps female dogs are more…ah…dramatic than the males? 
ChunkyLover53, sort of a “settling in” sigh? That would certainly go along with AskNott’s and Scarlett67’s theory of oxygen and rest.
I feel vaguely defient about all the bolding, after reading that thread in the pit, but hey, we only live once, right? Might as well bold while we can.
Breezy, I am especially fond of the irritated sigh. As I said before, it stikes me as the doggie equivlent of Passive Agression.
bughunter, I obviously agree with the passive agressive thing. And I wondered about the learning idea as well. The previous dog that we owned (or lived with, depending on your take) was originally my brother’s dog, Monty. Monty did not, as far as I know, sigh around my brother (I would ask, but knowing my brother’s e-mail return rate, we might hear an answer shortly before the sun went nova). He was around my mother (who was going through a sighing phase–I was a teen at the time and it was justified). After a while, it seemed like the dog picked it up. Interesting (to me at least). That could just be that the dog was more comfortable around us after a period of time.
Sorry about leaving you out of the big post. 'Twas not intentional, I assure you
My adolescent (23-month-old) male sheltie/basset sighs at all the same stuff you’ve all mentioned. And if THAT doesn’t get our attention, he starts up a whine that sounds just like a really out-of-tune cello.
Hilarious.
Unless I’m trying to sleep.
I work at an animal shelter and I’ve heard dogs sigh - they usually do it when they lie down. I have a cat who makes a sighing noise for no aparent reason every now and then
There’s a Comcast cable commercial built around a “martial arts expert” in which a golden retriever (IIRC) gets blamed for the television dish reception problem. The dog’s expression is classic. And perfect.
My 4 month old puppy sighs a lot, and it’s usually when he relaxes, and tension of some sort goes out of him. I have a book which clearly states that dogs don’t sigh from boredom, but only as a way of relaxing, but then, that’s just one opinion. I haven’t noticed that Buster sighs when he’s bored.
Considering that humans and dogs have been living together for 14.000 years, it’s not surprising that they’ve caught ‘mind’ from us. Dogs dream, which indicates a clear sense of self, something which is not evident in all animals. They obviously have personalities combined with the traits of each breed.
I think that dogs do adopt human manners, but that it’s a mistake to asign them human emotions. You often hear dog owners saying things like Oh look, he’s embarrased. I’m not sure that a dog is capable of feeling such a complex emotion.
Embarrassment = fear. Nothing complicated about that. :o
My dogs all sighed. Once in a while this behavior followed some sort of “disappointment” like not getting to go out upon request… but usually it just accompanied resting/relaxing (dog wakes up, shifts position, sighs, closes eyes… off to doggie dreamland again…)
My cats sigh too, on occasion - but they’re so much smaller/quieter than my long-nosed dogs were, that I don’t hear it too often. Sleepy kitty sighs - cute!