We have a two year-old, 50-pound mutt that is part Lab and part Blue Heeler. 99% of the time she is pure sweetheart. She is very obedient and loves to learn new tricks. She heels like a pro. Even when off-leash, she won't go down the step before we do. I can open the door and turn around and she won't go out the door until I do.

HOWEVER, and there's always a "however," when she is laying on the floor and my wife or I come over and begin to pet her she will sometimes growl. I haven't found a pattern for it except that it always happens when she's laying down. When she's on her feet I can do anything to her any time and she never growls. She growls about 20% of the time. A more common response is for her to roll over on her belly for belly rubs. Most of the time she doesn't have a toy with her, but when she does I can easily take the toy away. It's the petting that she's growling at. The more we pet her, or hug her or anything else, the harder she growls.

Corrections are rough. If she has a toy, I'll take it away while shouting "NO!" and she immediately stops growling and I'll pet her and say "good girl." When she has no toy, I've grabbed her muzzle and collar and given her a shake while I say, "NO!" This always leads to MORE growling. I'll simply hold her tighter while yelling "NO" until she stops.

What's even more strange is that sometimes when we've stopped petting her when she growls, she will immediately come over to us and give kisses and want to be pet some more.

This is the only agression we've ever seen in her especially when she heels so well, follows commands well, and frequently rolls over when we pet her.

I'm confused and a bit lost as to what we should do for correction. I don't want this to develop into some more.

I've checked her over and she doesn't seem to be in any pain.

If your dog is growling at you and you carry on petting her, you are just reinforcing her behaviour. If you correct her and you say that she growls more, than here to you are reinforcing her behaviour.
If your dogs growls at you or your wife or anyone else, You get up and walk off and you IGNORE the dog! And you ignore her for a good while, does she go lie down again then try petting her again, she growls, then do the same, get up and turn your back on her!
I know that they most common thing to do is to correct the dog, but in this instance it causes more of a conflict btw the dog and handler.
By the way, if you pet her in down and she does not growl, i would give her some kind of positieve reinforcement like a cookie and a "good girl" and that's it, no gushing over her and not too much of a fuss.. this will take a few good weeks before you see some real results. Practice and patience is the key.
Good luck with your dog

If I get up and walk away when she growls, am I not giving her exactly what she wants?

If she's laying down and begins growling, she stays down on her own. If I stop petting her, she goes back to looking out the window or whatever it is that she was doing as if nothing happened.

My personal opinion is that you shouldn't ignore the growling behaviour because I then you're basically giving in to her demands. I think this is something that could progress...especially if she learns it works.

If she continues to growl when you're giving her a correction, then I don't think the correction is strong enough.

Do you have a prong collar? The same correction with a prong collar would have more effect than a flat.

But absolutely do NOT pet her if she's growling.

Have you checked out Ed's articles on this subject? Really good advice there.

it was my understanding of what you wrote that if you stopped petting the dog that she directly became all sweet and asking for cuddles. I would defently not pet her when she growls. Maybe its best to ask Ed on this one...

I am not understanding exactly when the dog is growling or what the dog is growling about, I'm confused myself.

The shouting isn't doing much good, never does. My gut instinct is that she does not respect you.

Debbie

Obviously this is not a prey/food guard behaviour or a medical issue. I'm inclined to believe Debbie is right. A respectable correction may be in order. Chances are it will take only one.

I strongly believe that Howard is correct. One calm, perfectly timed good correction will most likely take care of the problem.

Debbie

If this were my dog, I would put a leash on her or better yet have a leash or tab already on her and take the leash, move her and then pet her briefly so that she tolerates being touched by me on my terms. I would then release her and she can go lie down again or whatever. If she came back to me for more petting, I'd say "no" and send her away, again it's on my terms. I'm still not convinced that she's not in some kind of pain or discomfort though if this ONLY happens when she's in a down. Just my two cents ~Angela