Pet spray suggestion: trust your good instincts on this one. When Johnny was a puppy at his worst, I was given something called "Caesar in a Can", which was a CO2 cartridge in a spray dispenser. I was told to spray it behind my back & that dogs didn't like the noise and so would be distracted or deterred from whatever. The directions on the product however said to spray the shoulder area. The gas is ice cold and there was a warning to avoid spraying near the eyes. I tossed it realizing this was like pennies in a tin can or yelping or barking in response to nipping, and I already knew that yelping and barking at Johnny only added to his frenzy. Because Johnny preferred to circle whilst jumping and nipping I was concerned about getting it in the eyes of my whirling dervish. No criticism intended; it wasn't a solution for us. The trainer's suggestion of this - surely - assumes Lab_life has lightning fast reflexes and will get to the puppy before he nips her son. I would be afraid to use a CO2 spray if the pup and child were in close proximity and moving unpredictably.
Have you tried distracting the pup with treat finding. Willow loves playing find the treat. She gets very hyper when out and sees other dogs. The other day she ran off accross a field towards 2 dogs I shouted find it then dropped a treat close to me. She came running back all thought of the other dogs gone and total focus on finding that treat. Start by shutting the dog in the kitchen and shut the door hide a treat then open the door and tell him to find it. They love this game when the pup bites your son throw a treat and say find it hopefully this will distract him enough to eventually stop the behaviour. Better than squirting with water and more enjoyable for the dog.
