Little dog very possessive - causing horrible fight w/ other dog?

She needs to be taught that the toys are your toys, not her's nor Buddy's and that they only play with them when you let them. I would only let them have toys when they are on leash so you can keep them apart until you can stop her from being so possessive. Is she possessive when you take a toy from her? Try having a training session with just you and her in which you teach her take and give commands. Tell her take and let her have the toy. Then offer her a high value treat and say give. If she gives you the toy, you give her the high value treat. Repeat this several times and when you are done with that training session, say give and when she gives you the toy, give her the treat and put the toy away and out of her sight. Work on this in 5 minute sessions 3 or 4 times a day for several days. You should also go through this same process with Buddy. After both dog's have learned this, you can again try giving them both toys while they are on leash to see if there is any improvement. I hope this works for you because eventually Buddy may seriously injure or even kill Julie.