I was wondering if I could hear a few pointers from the good people on these forums who know so much about BCs. I purchased a BC puppy from a breeder around the end of August. He was 14 weeks at the time that I purchased him- I received him at 14.5 weeks. I did not meet this puppy before purchasing him. The breeder came highly recommended by a friend with LGDs and another friend with BCs. The breeder does trial with their dogs. The sire is actively competing at the Open level in USBCHA. I'm not sure about the dam. I don't want to be more specific than that yet because of the nature of this post. The puppy I received was in good health. This was my first puppy (besides foster puppies) and my fourth BC (besides foster BCs). The previous BCs have been rescues. A few days after getting him, I started taking him out with me. We visited the park, downtown, and various pet stores. I found out right away that he would bark at dogs he saw in public. I began working with him and any strange dog we saw at a distance and rewarded him for paying attention to me instead of dogs that we passed. Now, at 6 months of age, he still barks at strange dogs. I went to breakfast with a friend in the week that followed bringing him home. We both brought our puppies (hers is a French Bulldog), who are almost exactly the same age. My BC puppy, upon seeing that the French Bulldog was receiving treats as a reward for sitting, immediately decided to aggressively bite the French Bulldog for taking food from me. This was the first sigh of aggression I saw from him. A few days later, I began having trouble with the BC pup and my Chihuahua. He started bullying her, pushing her around, bouncing all over her, and rolling her like she was a toy. The two were separated after that- the puppy was no longer allowed to roam freely while the Chihuahua was loose and vice versa. He also began barking and lunging at her when he was in his crate. I covered his crate. Things went well for a little while after that. He and I started bonding over playing and training every day. He got along famously with one of my older BCs and copied everything that BC did, which was adorable. My parents moved into the house about a month ago (I have been taking care of it for them but am moving soon). They brought their Xoloitzcuintli with them. The Xolo is a difficult dog- very vocal, very standoffish, a lot of negative energy. He is good with people, but not great with other dogs. We introduced the BC pup to him slowly. It didn't go well at all. We ended up having to shove the two of them in the same hotel room for two days because we evacuated from Hurricane Matthew and it was an absolute nightmare. The Xolo will bark and lunge at the BC pup. The BC pup responds in kind. They have gotten into fights. The BC pup attacked the Xolo for taking food from me (both were leashed and easily pulled apart). After that, they we returned from the hotel, they were put on a strict crate/rotate schedule and the two are not allowed to spend any time together whatsoever. Unfortunately, I think the damage was done. The BC puppy still reacts to the Xolo's barking. As soon as he hears that dog barking and moving around, he responds by barking and lunging at the door of his crate. (Or, if he is locked in my room, barking and lunging at the door). This was quickly followed by displaced aggression on ME. BC pup began displacing on me when he 1) could hear the Xolo but couldn't get to him or 2) was being blocked from going in through a doorway he wanted to go into. After this, the BC pup was placed on a VERY strict schedule of tether training. He is not allowed to run loose in the house, ever. He is always on a leash, always watched, always managed. He is allowed to run outside and gets plenty of exercise by playing frisbee, swimming in the pool, going for long walks, and having training sessions. But inside, he is either on a leash or in a crate. Today I was working on him with taking treats while the Chihuahua was taking treats (he usually tries to go after her for taking food from me but we were getting there with a lot of eye contact work and the "Look at That" game). He was doing very well until the Xolo, who was two rooms over, started barking. He immediately appeared stressed. His expression changed and he lunged at the door, barking. He then went after my older BC, the one he follows everywhere. I crated him so he could calm down and came online for help. We are in an area where there aren't a lot of trustworthy trainers (northeast Florida). I'm going to Connecticut next week to work with some trainers I know and trust up there, but I would like to hear input from the people here as well if possible. Does it sound like this puppy is just being a jerk or is there something I need to be more concerned about? Am I not doing enough for him? We are planning on starting herding lessons soon- that was always my intention with him. But I'm worried now. He barks at animals (ducks, ferrets at the pet store, cats, other dogs) and it's VERY difficult to get him to stop. Will he bark at sheep? Is this a common BC problem that I've just never run into before? Any and all advice is very much appreciated. To recap, behavioral issues include: -Barking/lunging at Chihuahua while BC is in crate -Displaced aggression/frustration when being blocked from going through a door he wants to go through or being blocked from going after another dog. -Aggressively chasing down any dog that walks by his food/a bone he is eating. -Aggressively going after a dog for taking food from me. -Barking at other animals when in public with very poor recovery from the experience (fur on back is usually standing up when this happens). Daily exercise regimine includes: 2-3 games of frisbee per day (mostly 2, sometimes 3), with lots of tugging since we are still learning to retrieve. 10 minutes of swimming in the pool (or until he is tired- he LOVES the pool) Walks around the block/sometimes a longer walk at the park (2 miles). 2-3 training sessions per day. Also always technically "in training" when he is out and about in the house. 1 flirt pole session every night to get him nice and tired before bed.