or no signals at all. Signals are generally different for self-defensive dogs versus those who are truly aggressive, as in competitive aggression. Tortora in 1983 experimented with a shock therapy to retrain avoidance-motivated aggressive dogs to condition them with safety cues, a process which he called Safety Training. He wrote that this therapy, when successful, had long-term benefit for the dog and its owners. Predatory aggression Predatory aggression is usually seen as part of the prey drive sequence starting with a visual or auditory trigger followed by chase, capture and kill. Predatory aggression is impacted by anxious influences, which results in the expression of affective aggression. This type of aggression is caused by sympathetic system activation and is non-affective. Based on a study that examines the predatory aggression in German shepherd dogs, this type of aggression is rarely displayed by dogs. However, if it does occur, it is usually directed towards unfamiliar dogs. Furthermore, predatory behavior activates reward centers in the central nervous system. According to Gonzalo and colleagues, this type of behavior is rewarding and therefore difficult to change. Predatory aggression is displayed by mature and intact males and this type of aggression results in serious damage to others. It includes actions such as chasing, biting, catching and may involve death or injury. Maternal aggression Maternal aggression is displayed by mothers when they are approached and particularly when their offspring are young. This type of aggression is linked to pain such as in cases of mastitis. Oxytocin plays an important role in the early bonding between the mother and her offspring. Dogs with maternal aggressiveness are protective of their offspring and nest. The change in hormone is linked to lactation, and the mothers can change the dogs' perception and assessment . Maternal aggression may lead to bites or other attacks. Maternal aggressiveness affects the growth and socialization of puppies. Furthermore, this type of aggression may stem from unstable social environments. Maternal dogs are very protective of their puppies and their aggressive tendencies decreases as their offspring grow up and they are able to defend themselves. Causes Gut microbiome The gut microbiome is linked to numerous health problems such as diarrhea and bowel disease, which results in pain and can possibly lead to aggression. The gut microbiome affects the affective disorders such as anxiety, which contribute to canine aggression. Based on a study carried out by Kirchoff and colleagues, the