I'm sorry to hear about the incident at your shelter :( We just had something similar happen, and just today had a local trainer come in to lead a safe handling training that's a level above and beyond our "regular" kennel safety and animal handling training. One of the most helpful pieces of the training was taking time to practice different leash holds and maneuvers with life-sized stuffed dogs. It feels a little silly at the time, but is so helpful in starting to build muscle memory. As a starting place, ASPCA Pro has a good webinar ("Defensive Dog Handling") that outlines helpful tools, how to use them, and other handling procedures for potentially dangerous dogs. Making sure you have safety tools easily accessible - and that staff know how to use them - is critical. We keep noise makers (shake cans, air horns, compressed air canisters), citronella spray, and break sticks/bite sticks in specific, marked places in the kennels, and all staff working in/around carry walkie talkies so that they can quickly call for assistance if needed.
I hope this is helpful!
Cheers,
Cynthia
Animal Care Manager, Humane Society of Chittenden County, South Burlington VT
#AnimalBehavior,TrainingandEnrichment