Would any soldier hold a leash, or were there specific dog-handlers? And is there any credibility to the idea of "piriferi", dogs who had buckets of flaming oil strapped to their backs before being released on the enemy?
Dogs were primarily used for patrols and guarding duties due to thier ability to sense approaching humans before humans could. However, they were also used for direct warfare, and wore light armour. Thier primary battlefield focus was to try and get the opposing forces to break rank by causing panic and discord inside the enemy lines. They were also supposedly good at spooking camels, horses and elephants. This would however have been a double edged sword, as there is no guarantee they would not spook your own mobile animals as well as your own soldiers in a close fight, so medium range would be the most effective to deploy towards your enemy while advancing infantry would try and take advantage of the chaos they could cause in the enemy. Mastiff and Molasser dogs were commonly the most effective and sought after breeds.