Small dogs hate V-Twins - while riding through the classier parts of town (Knightsbridge, Chelsea etc) I often observe Shitzus, Pekinese etc going berserk at the sound of my approaching V-twin.
Lol Anyway our neighbours had a Rhodesian Ridgeback that chased anything coming down the road. Cars, bikes, vans and yes even cyclists. Totally indiscriminate.
A dog is agressive to anything it feels threatened by, so lack of exposure to cyclists as a pup makes them wary as adults.
Ridgebacks are very territorial and one-person-dogs too, so they will automatically protect the homestead against anything they don’t recognise.
It could have been a Focus car door banging and frightening the dog once, that’s all it takes if you don’t show the animal they are not to be frightned off. Go and sit in a Focus and call the dog over, then ignore the dog.
Failing that, destroy all Ford Focii as they were the leading vehicle involved in bike collisions in 2006-7.