composition of gut microbiome differs on the basis of aggressive and non-aggressive assessments. In this study, the researchers tested rescued dogs that possessed aggressive and non aggressive behavior. The dogs were tested in the same environment, ate the same diet, and were consistent breed type, but variation was still present in the gut microbiome. The results of this study show the difference and abundance in lineages in aggressive and non-aggressive groups, indicating that an aggressive dog displays physiological conditions in their gut, which affects the composition of the gut microbiome. It also shows that the gut microbiome is associated with aggressive behavior. Lactobacillus are present in the guts of dogs that exhibit aggressive behavior, even though strains of Lactobacillus rhamnosus reduce stress and anxiety in mice. However, Fusobacterium is present in the stool sample of dogs that display non-aggressive behavior, even though it is known to evoke pro-inflammatory effects of gut microbiome. Anxiety Some aggression stems from generalized anxiety. The dog cannot determine the difference between a legitimate and false threat. Some signs of anxiety include dilated pupils, constant yawning and lip licking, ears pulled back, trembling, tail tucked and lowered body or head. An anxious dog may pace or be unable to relax even when there is no threat present. Anxiety screening was used in behavioral evaluation of children-directed aggressive behavior in dogs and according to Reisner and colleagues, 77% of animals displayed abnormalities. Aggressive behavior in dogs is often associated with fear, the separation from their owner, or noise sensitivity, all of which may result in or contribute to anxiety disorder. Fear In a study that examines the prevalence, comorbidity, and behavioral variation in canine anxiety, owners of fearful dogs reported that their dogs demonstrate behaviors they consider aggressive, such as barking and growling, to strangers and other dogs. The owners of 673 dogs noted that their dogs express fear by barking, and growling. The presence of aggression in dogs is associated with defense mechanism. Based on this study, there was an increase in bites towards strangers and familiar people when the self-defense response was not heeded, such as by cornering an avoidant dog. However, Abrantes points out that aggressive behavior in dogs is behavior that causes pain or injury, and HSUS explains that barking and growling are normal communicative behaviors for dogs not necessarily indicative of aggression. Breed, socialization, and health status It is important to recognize