[Britster]

Is she on leash when these off leash dogs approach her? Often, dogs feel the need to be defensive when they are restricted and others are not. We have a lot of dogs who roam loose around here too as we're in the 'country' and there's this one Lab that has charged us a few times. I had to pick Jackson up, for his safety, and he gets VERY defensive. He's not an aggressive dog and is quite dog friendly but the act of me picking him up makes him feel defenseless I think. He also does not like boisterous large dogs with no manners or good doggy language and I think it's quite normal for a little dog to protect themselves, for most DO in fact realize their size. A lot will say "oh they think they are a big dog" but really, most of the time, it's that they REALIZE they are small and that is the only way they know to protect themselves.

I would try to find a local meetup group for small dogs, where dogs are well behaved and confined to an outdoor fenced in area, etc, or an indoor, and see how she gets along with dogs in general. It doesn't sound like she's truly dog aggressive since she does get along with some dogs.

However, terriers can be prone to dog aggression more than other breeds, and sometimes right around 1-2 years old, they begin to mature and develop their dislike of other dogs. Not all dogs are going to be good 'dog park dogs'. Yorkies in general don't seem to have quite as much of an issue with dog aggression as some other terrier breeds though.