Once, in 4 years of carrying. The wife and I were walking a new puppy around the block, when a huge dog jumped it's fence and came straight for our little Molly. My wife scooped up Molly at the same time I drew my weapon. I had pressure on the trigger when the attacking dog stopped, followed by it's owner yelling for it to stop. The owner jumped the fence to retrieve his dog while I was still holding my pistol on it.
In Texas, I was perfectly legal to draw.

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Proud USAF Dad