well, beyond my personal experiences with being sprayed (and it not deterring me) and spraying others (and it not deterring them), here are some sites for your perusal:

- http://answers.yahoo.com/question/index?qid=20080626225520AAlKL5t

"Why doesnt pepper spray work on Pit Bulls?Is mace the same thing? Wow! And I cary mace with me everywhee. here's the news from San Diego.
UNION-TRIBUNE

June 26, 2008
ESCONDIDO: One of two pit bulls that attacked a woman's dog and couldn't be subdued was shot and killed Tuesday by an Escondido police officer.

Neighbors saw the dog being attacked and initially fended off the pit bulls with shovels, Escondido Lt. David Mankin said.

An animal control officer tried to catch the pit bulls, but the dogs approached the officer aggressively, said Abigail Rowland, development director of the Escondido Humane Society.

When a police officer arrived, the pit bulls began circling, Mankin said. The animal control officer used pepper spray, but it was ineffective. When one of the dogs ran toward the police officer, Mankin said, the officer shot it twice.

The dog that was attacked was expected to survive, Rowland said.

Authorities captured the second pit bull. The owner of the dogs, who was...."


"Pepper Spray Works, But Don't Bet Your Life On It
Article #1245"http://www.gi.alaska.edu/ScienceForum/ASF12/1245.html (bears, but the physiological responses can be equated)

Lastly, consider this: while a spontaneous, opportunistic attack by a 'friendly' breed could be deterred by the application of OC, a predatory - or as Cesar Milan has quiped - a 'Red Zone' - dog may not be as willing to go along with your plans. There are no hard and fast rules...the effectiveness of it on committed, human, attackers is debatable (again, personal experience, YMMV).

Also, one must take into account the ability to recognize the attack (from an animal that - if relying on its predatory instincts - will not give you advance warning) and physically manipulate the OC in a way that 1. it hits it's intended target and 2. doesn't inadvertadly handicap you.

am i saying pepper spray is useless? absolutely not...if given the best of circustances, it could very well prevent serious injury to you and the dog...but, when it comes to being thrashed by a maniacal hound, well this is neither horseshoes nor handgrenades...i'll go with lethal force - pepper spray if they're lucky and i have time.