i am someone who has nervous issues around big dogs! i was bitten as a child [unprovoked by me] which, i believe, stamped a message to me that a dog can bite for no reason. so, unless i have known a dog really well [i.e., helped with training, etc] since it was a puppy, i have to take some steps to make myself be more at ease around them.
i do not get paralized by fear, but it's likely that i will avoid the dog. here's what makes me feel better and more confident: knowing i have some measure of control over the dog. if i can tell the dog to sit/down/off/go-away and the dog totally obeys me, then i don't feel that the dog is a threat and in no time, the dog and i can become great buddies. this is often reinforced by watching the dog and a child interact, and seeing the dog obey the child and play well with the child.
it has also helped me to have read books/articles about dog behavior and body language. if i feel i can read the dog, i am more confident.
if she has experience with toy breeds, that may have actually made things worse... i find that many toy dog owners allow lots more misbehavior because the dogs do less damage. getting snapped at/growled at by a small dog is laughable. realizing that a large dog could do the same is scary. [note: this is partly why when we get our next dog - a large one - it will be a puppy.]
anyway, if your friend is willing to work with you on this, and tosca is well trained in basic obedience [she seems to beautiful and well cared for not to be], maybe taking them outside and having your friend get tosca to do some obedience for her might help?
