A biking friend told me a story about a riding friend of his, former Army. Kept getting attacked by the same dog, would yell at the owner and the owner would yell back. At one point, the Army guy shouts "If that dog attacks me again, I'm going to kill it". Apparently, several days later the dog chased and bit him. The guy stops, pulls out his 9mm Beretta, and shoots the dog between the eyes. The owner is freaking out, calls the police. The Army guy makes the weapon safe, puts it in his bike bag, puts the bike against a tree about 30 feet away and then walks back and sits down on the fence and waits. Cop comes. Ex-dog owner (That is, the owner of the ex-dog) is telling the cop to arrest the Army guy. The cop asks the Army guy if he has the weapon, and the Army guy says "Not right now, but an unloaded weapon is in my bike bag over there, along with my concealed carry permit. The cop says "What happened?". "For the 15th time in 30 days, the guys unleashed dog ran out of his yard and chased me. Two days ago, I told the guy that if he did not prevent this, I'd kill his dog. Today the dog chased me, and bit me." Showed the cop the teeth marks and the blood on his leg. The owner is screaming "See! See! Arrest him!". The Army guy says "I checked into the law, and let me be easy on this guy. If he shuts up and promises never to get a dog again, I won't press charges for his dog attacking and maiming me". The cop looks at the owner and asks "Was your dog on a leash?" "Uh, no". "Then I suggest that you take the injured fellow up on his offer".

For a less, err, aggressive approach (not many people want bicycles to become light unarmored mobile forces, including me), perhaps copy the note you sent to the owner of the rental unit, and cc the five most highly advertised tort lawyers in town. Then let the owner know that the forces of the Dark Side are arrayed against him if anything happens.

Even less aggressive would be the bacon approach. But then you gotta remember to have bacon bits in your cycle shirt every ride!

Pepper spray is a good conditioning approach. It teaches the dog not to bug you, and hopefully other bicyclists.

I always worry about a big dog bounding out and scaring a little girl on her bike with training wheels into stearing right in front of a Ford F-350 SuperDuty. I love dogs, but their owners are often idiotic.