Hello All!
Max is a 6-year-old lab/mastiff mix. He weighs about 85lbs. I've had him for three years.

Before that, he was owned by another woman, but the first 7-9 months of his life are unknown. My vet has known him since he was 7-9 months, and said his first owner never did anything with him (obedience, etc) and really never worked with him at all.

He's my first dog, so we did obedience classes for several weeks, as much so I could learn as him. He walks well on leash, will heel on and off leash, will sit, down, stay, and come on command. I make him wait for his food until I release him, and often will make him wait until to chase a ball (his favorite game). He gets along well with my cats. He has never shown any dominance towards me. He's also hypothyroid, and takes medication for it.

I'm a single woman, no kids, who lives out in the country.

Max is shy of strange men, and especially, it seems, repairmen/construction workers. Twice now he has bitten. He does not attack, but when the man tries to pet him, he shows fear behavior (tail down and wagging, hiding behind me, and so on) and bites. The first time didn't break the skin, and I wasn't sure that it wasn't a fluke--the guy was very high strung and pretty much jumped at the dog.

The second incident was worse, the man ended up with 5 stiches in his hand. Both times Max was on leash, and both times, I warned them that Max isn't good with men. Both times, I was stupid to give in to their "I'm good with dogs" bit. Doesn't matter. Max isn't good with them.

After talking to my vet and a behaviorist, my decision is this: continue to reinforce obedience with him. Have him wear a basket muzzle when strange men come to the house.

Oddly, Max's dog sitter when I'm out of town is a neighbor's 18-year-old son, who Max adores. It turns out that his father came into the house once, and Max was fine.

So besides protecting Max and the repairmen, I'm wondering if part of this is me--after all, I greet a friend differently from how I greet a repairman. If a repairman is in the house, I'm probably already a little anxious. Is my dog picking up on that? Am I abetting this fear biting?

Sounds like you took pretty reasonable precautions to me - you had the dog on leash, and you gave warning. Unfortunately, dumb people will force themselves onto dogs, as you found out ( it's happened to many of us, believe me )

I'd just put Max up when men come over - problem solved there. Does the big fellow have a crate? If he must go into public where men are around, the muzzle seems a good precaution.

You've done better than 99% of pet owners, don't beat yourself up here! All dogs get suspicious when strangers come to the house, that's hard-wired in the canine brain. No amount of discussion with my male GSD can convince him that the garbage men are not serial killers, hence he's crated on garbage day so he doesn't fly through the window at them.
Precautions are our friends for good dog ownership! <img src="/ubbthreads/images/graemlins/laugh.gif" alt="" />

Thanks, Will. I was pretty upset after this incident. A friend immediately said I should have Max put down. I forced myself to consider that, as well as every other possibility. In the end, I'm hoping my plan will work for all. He's my first dog, but other than this, I couldn't ask for a better one. He's calm, attentive to me, house broken, obedient, and only barks when there's something to bark about (like in the middle of the night when some pipes burst; if it hadn't been for him, I would have had a flood by the next morning!).

The one part of my plan I'm not sure about is our ball playing sessions. I have a fenced in area, but generally use my ten acres to give him some real room to run after a ball. Short of a whole heck of a lot more fencing, I'm trying to think of a good way to still let him have a good work out with his ball, while not worrying about a UPS man or someone coming around. It hasn't happened in three years, but let's face it, it could...

Don't laugh, but I was considering getting some agility equipment to put in the fenced in area. Yeah, he's a big boned, clumsy dog, but then I could combine ball and exercise without acreage--and then just take him on leashed (or muzzled) walks in the woods.

Forgot--yes, he has a crate. I crate him only while I'm at work. Keeps him out of the garbage. <img src="/ubbthreads/images/graemlins/smile.gif" alt="" /> And he loves the crate.