Aggressive dog behavior in livestock guardian dogs sometimes becomes an issue for new and even been-around-awhile owners. So take heart - you're not alone in dealing with dog issues!
Aggressive Dog Behavior with Other Dogs
Some livestock guardian dogs are quite aggressive with any dogs who approach their stock but in particular to dogs they don't know.
For producers using herding dogs this can be a concern. Yet livestock guardian dogs are very smart creatures and when the herding dog shows up with the producer the guardian dog knows it belongs and leaves it alone.
Producers can also help by alerting the flock guardian before releasing the herding dog to gather the stock.
Aggressive Dog Behavior to People
People that are unknown to the livestock guardian dog may be threatened - usually by a bark or sometimes a silent visit to check them out. This is the nature of these breeds and why they are selected for the job. It is rare that these dogs will act overtly aggressive to people. A warning is usually all it takes.
Dog Wants to Guard the Porch
This is a sure sign that you have not done your job bonding the dog to the livestock.
Barking
Being vocal comes with the territory. Many breeds use their bark to ward off the approach of predators and tell them to go elsewhere. If you raise your sheep in your backyard you may have to grow accustomed to the sound of deep barking during the night. Some breeds are known to be more vocal when on duty than others.
Dog is Aggressive With the Lambs
This is often a matter of maturity. Adolescent dogs, even those raised with the sheep, often go through a phase of playing rough with the lambs. While the dog certainly knows that lambs are not dogs, this does not stop them from attempting to play or bully them as they would with other dogs during this adolescent phase.
Often the dog grows out of this but care and a watchful eye is warranted to be sure you don't have a class A bully and lamb marauder on your hands. A couple of appropriate corrections may be all that is needed. Alternatively a dog that is too young or too rough may be removed when the lambs are young and returned later.
Dog is Aggressive With the Ewes
As dogs and sheep grow up together they will pass through various stages of comfort level with each other.
Young pups (under a year old) will get knocked around by pushy ewes and need an area to escape to. As the dog matures he tends to have less and less tolerance for this behavior from the ewes and eventually retaliates once or twice to defend himself.
Many LGD owners prefer that their livestock guardian dogs always submit to the ewes, without exception, and that any type of defense behavior never be allowed.
However, we have noticed there is a phase where ewes and dogs work this hierarchy out themselves without doing any harm to one another. One or two gruff responses from the mature dog to ewes who head butt him and the matter is settled (much like a mother dog telling her charges to knock it off).
After that the dog and ewes respect one another and the dog ends up submitting to the ewes in various situations on his/her own.
Also on our ranch ewes and dogs are raised on pasture and well away from the yard. Unless you are living with your sheep in your backyard constant supervision to ensure the dog always submits is not feasible.
As an adolescent, the dog may pick on ewes, singling specific ones out to chase or harass and sometimes biting. If the shepherd catches this behavior in action he should correct it.
Occasionally a dog may prove to be too exuberant with the ewes and if his behavior is not curbed with age and/or correction then it may be the case that he is not suited to the job.
LGD's who are causing damage to ewes are displaying unwarranted and unusual aggressive dog behavior and need appropriate action immediately to ensure this does not become a habit.
Dog Won't Stay Home
While this is not aggressive dog behavior it is a common one. There are numerous reasons why a guardian chooses to go elsewhere.
Sometimes it may be a matter of the dog you've chosen as some are more prone to covering territory than others.
The neighbourhood dogs may become more appealing especially if any of them are females in heat.
If you have neighbours who do not clean up dead stock this may entice your dog off.
If you have not done your job in the guardian dog care and training department then he may always be enticed into doing other things and being other places.
This is often a matter of maturity. Adolescent dogs, even those raised with the sheep, often go through a phase of playing rough with the lambs. While the dog certainly knows that lambs are not dogs, this does not stop them from attempting to play or bully them as they would with other dogs during this adolescent phase. 
