When they became close as with a team, no stranger would dare lay a hand on them. Once the knowledge of this trait spread, more coach drivers went to great lengths to get Dalmatians to watch their teams. They were used by coach drivers centuries ago in England, Scotland and Wales. Horses are gregarious and feel the need for company. You can't leave them alone too long.
Dalmatians take to horses and become 'companions'.
Back in the stagecoach days, the 'Dals' would run alongside the coaches, or under the rear axle of the moving coach. They'd keep up with the team as far as it ran, sometimes over 20 or 30 miles a day. IF the coachman stayed to guard, a robber would sometimes distract him in conversation while others pilfered the goods. They couldn't pull that ruse on the Dal, since they're very alert dogs. When horse numbers grew here in the New World, the number of Dalmatians grew with it for the same reason they were popular in the Old Country.