Hello everyone I have an interesting question about my dogs recent behavior concerning one particular person.

A little background on my pup, he is a 112 lb German Shepherd who will be turning 2 years old on January 28th 2008.
He is dog aggressive but I am working to break him of that, however as far as people are concerned he doesn't really care about them other than a cursory glance.
He did show more than his usual interest once in a jogger but not in a violent way.

People who we meet out on walks are able to come up to us and talk to me and even give him a pat or two without issue.

Our daily walks include going to the corner store for the paper where I will leave him outside in a sit stay, (tied to a bike rack just in case another dog shows up while I am inside), he has never broken his sit stay as far as I can tell since he is always in the same exact spot as when I left him but I am only inside for 60 seconds tops.

One day about a month ago walking up to the bike rack at the corner store there was a woman sitting on the small concrete ledge in front of the store looking at scratch tickets, nothing out of the ordinary as there are always people either coming or going from the store.
Well as we passed her he took a whiff of her and just outright snapped, hackles up all the way to his butt, snarling, barking and lunging for her like he wanted nothing more than to kill her right there and then.
I got him under control, and apologized to this poor woman who during the entire outburst just sat there and stared at him.
There was definitely something odd about this woman, she was disheveled looking, had the craziest eyes I have ever seen and her hair was kind of all over the place.
Upon apologizing to her and having only the briefest interaction with her I got the impression that she was either slightly retarded or a little bit crazy, not to say that my dogs reaction was in any way ok because of this but I just got the over all impression that something wasn't quite right with her.

Just today while out on one of our walks we came around a corner and there was the same woman from the incident at the store.
I made sure I did not do anything to alert my dog but watched him closely, he seemed perfectly fine until we began to walk past her.
Once he got a whiff of her all hell broke loose again, my hardest correction barely dissuaded him from trying to get to her to do god knows what.
Once we where away from her he was back to normal just like the last time almost as if someone flipped a switch from kill to passive.

So my question is this, are there certain types of medications that will make a dog go ballistic?
Or does my pup Marcus just not like this particular woman for some strange reason?

Is his reaction to her similar to what he does with other dogs?
Maybe this woman sleeps with 15 dogs, or cats, or both. Maybe she has a very smelly Chihuahua in her pocket.
If you could plan to cross paths with this woman on walks it would be the ultimate test for the distraction phase of training.

We've all heard about dogs that have wonderful responses to children/physically disabled/mentally disabled/etc persons. Some dogs can have just the opposite reaction. I had a Kerry Blue that would absolutely freak out when around anyone "unusual". It's not uncommon.

Maybe the lady is just flat out creepy in a way that sometimes only dogs can see.

Sounds like the dog is probably reacting to your "reaction"...though I stand by the point that dogs are the best judge of character

Bayley is like that with a neighbour, charges the fence, barking, hackles up. She'll let out a few woofs when she sees other people in the neighbourhood but quiets right down if they talk to her. Funny thing with this neighbour, our local OPP came by the other day, looking for her, turns out she's growing pot in behind our yard..nice! From what I've heard she doesn't have a very good reputation around the area. I don't know if Bayley was reading my reaction to her. I don't react to her as far as I know but she senses something I guess.

Years ago, I had a very sweet, docile, well-trained Greyhound that was also a certified therapy dog. He was the friendliest, most cheerful dog I've ever had, and he loved EVERYBODY. Except for this one guy. There was nothing visibly wrong with this person, and in fact I thought of him as a friend. But every time he came around, my Greyhound was positively snarky. Late one night, I woke to the sound of barking and growling and realized this fellow had broken into my house. My Greyhound was over-the-moon and determined to take a chunk out of this guy, so he ran off and I called the police. SCARY. This behavior is extremely out of character for a Greyhound, but it lent some credibility to the notion that dogs are very good judges of character. So though I won't tolerate aggression, I do tend to trust my dogs' 'opinions'.

I have a good one on this topic. My mother had a boyfriend that my phoenix did not like. The first time they met she bit his ankle. And then i was working one day and she was watching my dog. She called me at work and said your dog does not like my boyfriend at all. This guy was a tow truck driver so always at work pretty much. Well i finally met him. My parents have been divorced sence i was 2 so im used to the boyfriend thing. Well i notice he had a tan line on his figure. And i ask her if he was married. she said no. Being friends with cops i had them look him up not only was he married but he was a sex offender. That had raped many of his supposed girlfriends. And his wife found out the next day. And he was arrested cause i was 2 days shy of 18. He is not supposed to be around any children

Thanks for the responses.

The reason I asked about a possible connection to any medications a person might be on is because he doesn't react to this person until after he smells her.

It's literally as if someone flips a switch as soon as he gets a whiff.

I was thinking that perhaps this person is on some type of medication or drug that might make her scent all wrong in his mind and therefore represent either the scary unknown or danger to him.

I don't know who this woman is and I have only encountered her twice and unfortunately my dogs reaction to her isn't very conducive to chatting so all I can do is hypothesise at this point.

Just one of those many occasions where I wish my dog could explain himself I guess, if only dogs could talk

Scott, I wouldn't worry about him. I have had this kind of thing w/almost all my dogs at one point or another. I had the exact thing w/Caleb and a woman matching that description. While I can think on the level of "That poor woman; I wonder what kind of circumstances caused that level of mental illness", my dog just thinks "Wacko. Threat." Or something similar. I was walking him around a square park and this woman would jump up on a wall and start spinning in circles and screeching whenever we came near. He went nuts the first time, full hackles, etc., which is not usual for forward aggression toward a person he doesn't like. The second time we saw her I was able to keep him quiet, but he did a natural (never taught this) reverse heel and stared at her until we were pretty far away.

Our big, black, beautiful dogs are fine; women are crazy.

He also had a reaction like this to my Uncle's girlfriend. He would walk in a huge circle around her or avoid her at all costs, even if it meant walking twice as far to get where he was headed. This was in the house, where he knew better than to lash out. Let's just say my Uncle should've paid attention. The nutcase is in jail for a whole slew of psychotic offenses.

Honestly, while I would force him to keep his mouth shut, I don't know if I'd correct him as hard as you can, since there really is something not right w/her. I would try to avoid her entirely. I guess I'd give him the benefit of the doubt since he's stable 99% of the time. We had a thread like this a few months ago, but I can't remember what it was called.