Dals are supposed to be that way. Their "working class" is actually Coach Dog (not to be confused with the similar looking Couch Dog...)
That is why you see Dalmatians at fire stations and also with the Budweiser Clydesdale wagon team. (and no it's not because firefighters drink a lot of beer...) Horses are naturally fearful of dogs. In the wild wolves eat mustangs, so it's an instinctive thing. Back in the days of horse drawn coaches, and long before even horse-drawn fire engines, the Dalmatians were raised in the stables right along with the horses. The horses knew and were comfortable with the dogs they grew up with... but ONLY those specific dogs. The coach dogs job was to keep the horses calm by keeping stray dogs, and people away from the horses. They way to do this was, yes, by being aggressive. As horse-drawn, steam-powered fire engines came into use, the Dals still had a job or running ahead of the fire engine, scaring off any stray animals. Once on scene, they had to continue to keep back any stray dogs, as well as what we firefighters today call the "oooo!!! AAAHH!!!!" squad: the gawkers who constantly get in our way and ask stupid questions. In time, as horses were replaced by gasoline and diesel, the Dals stuck around... but yes, they still can be a little snarly.
Disclaimer: My 2 dogs, Pumper (with the black eye) and Tanker are Dalmatian-Hound mixes. The hound mixture really mellows them out, but Pumper still has a little Dalmatian attitude in him. Tanker on the other hand, has the personality of a hound... if not for his brother barking at every car that drives by, he'd just lay in the sun all day...
