Hi Joseph, welcome.
Sounds like a pretty challenging situation you've got happening. I'm no expert, just a long time dog owner with some thoughts to share about your situation.
She bit my wife 3 times already for no reason.
Has she ever bitten you?
I currently walk her 2 times daily and play catch with her for 40 minutes in the mornings.
The walks sounds good, but short. 2 ½ blocks to the park? That takes what, about 3 minutes? And the 40 minutes of ball playing in the morning.
I've got a pretty high drive shepherd and 40 minutes of simply tossing a ball first thing in the morning would just wind him up. We do play ball, a few long throws but a lot of obedience is mixed in with it. I could throw the ball for him all day and I'm sure he'd just keep mindlessly chasing it. Making him slow down and think about what's gonna make it fly, responding correctly to commands, seems to drain a lot more energy.
I would probably cut the ball game down to about 20 minutes and use the other 20 minutes for a brisk, structured walk (with a back pack and a bunch of weight). Maybe there's a bit longer route you could take to the park. Once there, maybe take the pack off for a few commands and ball tosses, but I wouldn't let her wander around aimlessly. Her job is to be working with you. A nice structured walk home and leave a calm pup instead of a wound up one.
Normally when she is calm she lets us pet her and give her puppy love by tickling her tummy and stuff. My wife came up to her and sat next to her and started petting her for about 3 minutes
Maybe this is just me but I can't imagine giving any of my dogs a three minute tummy tickle. I've sat down with them for hours, maybe a limb touching and the odd belly rub here and there but I don't think I've ever petted one for a straight 3 minutes. Is she talking to her at the same time? It sounds like this would be incredibly stimulating for the pup.
When my wife stood up, at that moment our GSD just had a mood change and bit 3 fingers from her right hand and didnt let go until my wife started to scream and cry.
I have a rescue shepherd that will also bite quickly like this - under much, much different circumstances, but an instantaneous attack none the less. I do know exactly what triggers him though, how to avoid it and he's coming along nicely with work we've been doing on decreasing the triggers. It's a fear he associates to a specific approach and a "do unto others before they do unto him" type thing. He has an extremely low tolerance to humans other than myself and a couple others.
We are wondering if its possible that when my wife stood up and raised one of her hands she took it the wrong way. But we are not sure.
I believe you are correct here. On top of the 3 minutes of the petting stimulation, has she ever been corrected for acting out after something like this before? Pet, pet, pet and maybe she got a bit mouthy or paws flying around in excitement and a correction followed? Has your wife ever corrected her after petting her for any reason?
When she's calm and being good, this is a good time for the human to be rewarded for the great job they did getting her there. (In your wife's condition, perhaps some peanut butter on pickles.
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Many people feel that petting is a reward to a dog and in a lot of cases it is. In some dogs though, it's not. It's more of an opportunity that people tend to take advantage of to meet their own furry, fluff ball, nurturing needs. She's calm - good opportunity for me show her what a loving and kind person I am. Unfortunately, the relaxed dog now is exposed to an exited human and that just starts the whole cycle of "behavior" all over again. There's a lot to be said for "Let sleeping dogs lie".
If your wife feels she needs to pet her, I would look at reducing the duration substantially. You can always work up to longer cuddling sessions. I would be paying close attention to the departure or time when she is ending the petting session. It almost sounds like you have an opposite problem to the one I'm dealing with. Mine has a problem with the approach. I would be very conscious of where my hands are and the smallest movement that may be causing a change in her body language, what seems to be triggering it. Once you get this figured out, desensitization exercises can do amazing things.
Most of her problems are when she is at home during the day, or when we are in the car driving to the store.
I would be paying close attention to these. Even documenting them. Accurate, documented accounts will be extremely helpful for a behaviorist should you choose to take that route. At what point does it start – when you shut the door, when the indicator light is turning left, when you pull into the store parking lot. Does she turn and chase a specific way, is it more intense at different times.
Is her aggressive behavior fixable?
I believe it is but I’m also an eternal optimist,
sort of.
However, very little that's worthwhile comes easy. Your dog is out of control and IMHO, bordering on really messed up. Something got her here and I don’t think it happened overnight. You guys need to be really honest and open to what you need to hear and the work involved in turning this around. It sounds like you’re up to it or you wouldn’t be here.
In my calculations you have about 3 months before the baby is due to arrive. I would be using every minute of spare time to get this turned around. Triple the exercise and mental stimulation if possible, don’t give her a chance to chase that tail and as Anne has stated, control every movement.
A bit of work needed, but I'll bet your girl is well worth the effort.
ETA: Can I ask what you're feeding her?