I may be far off the mark here, but could she be dreaming?
My dog makes the strangest noises when dreaming sometimes: howling/yipping/ and sometimes letting out a long moan which sounds terrible. I don't normally wake her from a dream, but if on the odd occasion she does wake, she is always her normal self.
That's just a thought. It may not be that at all.
Since your vet did a very thorough workup, my guess is this is a frustrated dog dreaming out loud. I had a dog very like yours who started howling in her sleep around the same age. Very scary stuff there!
As it turned out, she needed proper exercise outside her own territory. Once I started a daily walking program, she calmed right down and we all slept in silence again. If you already walk your dog daily, you may need to add an extra one. Can't hurt - might help!
Dogs can be incredibly vivid dreamers! Whenever I watch a video about wolves (particularly wolves) my dog often howls in her sleep afterwards!! She hears the howling in the video, and it carries over into her sleep. I would love to see what dreams she's having!
Jaybay has a good point. Most dogs need challenges as well as exercise in the day. They need to problem-solve in one way or another, and the more intelligent they are, the more they need that. Walks in new territory are an interesting thing for them. Extra mental stimulus.
And most healthy dogs need more exercise than humans are normally accustomed to!
To be a five-mile-a-day (or even more, if necessary)person is almost obligatory with an energetic healthy dog around. However, even a happy, healthy, well loved, well exercised dog may still have vivid dreams. As long as you are sure they ARE dreams, and nothing else can be wrong, then a pair of earplugs when sleeping at night will come in handy!
Thanks for you response (and sorry for my delay I've been away from internet access).
I guess my original post may have been slightly misleading. I don't believe it is dreaming as it also happens in the day (we just notice it more in the evenings as she is lying next to our bed). She will let out big moans and groans shortly after just lying down if she is shifting positions (just rolling slightly while on her side) as well as just lying there. I am confident that she is not asleep. The evening moaning is more of a concern as I believe whatever it may be wakes her up.
Any more ideas or suggestions would be greatly appreciated. The vet has given me a generic pain medication which I started yesterday to see if it eliminates the moaning, if so, we will still be exploring as it will prove it is pain related.
Right, I see. I did assume you meant it was just when she was sleeping...
That is a good idea, to give her the pain meds, if the moaning stops, then it is most likely pain related (or pain/inflammation-related, if the meds are also anti-inflammatory)
Then I suppose the vet will run a series of tests to find out the cause of her pain.
I hope it is nothing serious, and the mystery is solved. If it happens to be arthritis, then a Glucosamine/Chondroitin supplement can work wonders.
I hope things work ok for her.
My dog does the exact same thing after laying down or sleeping. She is a bichon/terrier mix. When I try to explain it to someone or to the vet they all say she is probably dreaming. I know she is not. She first starts letting out little whimpers and then it escalates into painful yelps. My other dog even runs to her aid. When I try to move her she freezes up. Shortly after she is fine and alert and will run and play like nothing was wrong so she doesn't seem to be in pain. I am going to try and video record her next time this happens so that I can show it to my vet. It doesn't sound like it is common so it's difficult to explain to people who haven't seen it before. She isn't dreaming..I know this for sure!