Dog behavior is formed by a combination of genetics and environment, which can lead to a well-adjusted dog or one who exhibits strange behavior. Dogs that exhibit strange behavior can often be rehabilitated with the use of training and medication, but it's important to understand what your dog may be going through when exhibiting strange behaviors.
Medical Causes
Strange dog behavior can be defined as any behavior not exhibited by most dogs, such as aggression, resource guarding and separation anxiety. The definition can also apply to unusual behaviors such as self-mutilation and obsessively chasing one's own tail, other objects and even visual cues like light.
Many of the behaviors from the second category are caused by neurological disorders, not simply behavioral disorders. These can be very difficult to diagnose because X-rays are costly and may not reveal what is causing the problem. However, strange behaviors such as a dog attacking himself during resource guarding can often be significantly reduced with medication.
If a behavior appears suddenly, call your veterinarian before calling a trainer. Though a training program may be necessary in conjunction with medication, one is often not effective without the other.
Fear and Anxiety
If medical causes are ruled out, a sudden behavior change may also be caused by fear or anxiety. If your dog is in his crate during a thunderstorm and is startled, he may develop a severe phobia of his crate. Since you weren't there to see what happened, you may have no idea why this occurred. But there's a very real reason to your dog.
Many of these fears may have developed before you even adopted your dog. These fears could have been caused by bad experiences or lack of socialization. Dogs who are abandoned, for example, may develop separation anxiety so severe that they crash through windows or break teeth and nails or mutilate themselves trying to escape.
If your dog learns to fight back toward its fears, fear may exhibit itself as aggression toward strangers, other dogs or even the owner.
Medication may still be needed in this situation, but training will also be required. Your dog needs to learn to be calm and develop calm associations toward these fears.
Boredom
Many dogs are severely underexercised and understimulated, causing them to redirect this energy into destructive behaviors. This is most commonly seen in dogs who are kept in kennels for long periods of time, such as dogs that compulsively spin in their cages and can't seem to stop, but they can develop anywhere.
These behaviors are best avoided by providing your dog with proper exercise and mental stimulation. They can also be corrected with medication and/or training programs that teach the dog new skills when they begin to feel stressed or overstimulated.
Learned Behaviors
To make matters more complicated, strange behaviors may have started because of medical causes or fear but have now become so ingrained in your dog's behavior repertoire that they are now habit. This often makes it more difficult for owners to understand because they seem to have no cause.
Treatment often involves medication and training. Though these behaviors are habitual, new behaviors can be taught to take their place, allowing your dog to handle stress in a more calm, healthy manner.