Dog aggression
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Dog aggression expressed by dogs is considered to be normal behaviour and various types of aggression are influenced by a dog's environment and genetic predisposition.<ref name=pmid12854682>Template:Cite journal</ref> Dogs commonly display possessive aggression when defending resources or themselves.<ref>Template:Cite journal</ref>
Canine aggression may be influenced by a dog's age, sex, health and reproductive status.<ref>Template:Cite book</ref> Canine aggression is one of the most serious behavior problems in animal behavioral medical science.<ref name=pmid24972077>Template:Cite journal</ref> Aggression in canines is particularly important because a dog's sharp teeth can result in serious injuries,<ref name=pmid24972077/> or even fatalities in the young or frail.
The determinants for each type of aggression are different, but there are specific factors that are common to canine aggression.<ref name=pmid24972077/> The types of aggression include dominance aggression, defensive aggression, predatory aggression and maternal aggression. Aggression in canines may be a self-defense response to a person or animal entering a dog's space,<ref name="frank">Template:Cite journal</ref> which may be ritualized aggression, not actual aggression, if the violation includes a threat. Aggressive behavior in scared dogs is typically not true aggression but rather ritualized behavior intended to avoid physical altercation by way of faking aggression<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> rather than actual aggression, anxiety disorder, diet, gut microbiome or genetic background. Some aggression can be treated through animal behaviour therapy or avoided by proper socialization during puppyhood.
Types of aggressionEdit
Dominance aggressionEdit
1) Punishing dogs has been associated with a strong likelihood of new or increased aggression and other behavior problems; 2) dominance in pet dogs is not a character trait of a dog but rather a power agreement between dogs regarding who has best access to particular resources; and 3) the behavior of dogs controlling access to resources is fluid, not static, depending on context. There is also data suggesting that the concept of spoiling a dog is often a misnomer, that this perceived spoiling is often a matter of meeting the dog's emotional and physical needs.<ref name="Hsu & Sun 2010">Template:Cite journal</ref><ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Defensive aggressionEdit
Defensive aggression, also known as fear aggression or avoidance-motivated aggression, occurs when an individual approaches and interacts with a human-avoidant dog. The dog might first try to flee, but may resort to aggressive behavior if cornered, as a means to try to defend itself from a real or perceived threat. The dog displays aggressive behavior in an attempt to avoid a real or perceived negative consequence, such as to avoid pain. Dogs may display a multitude of behaviors leading up to an attack including fear and stress signals, defensive posturing, facial expressions, or no signals at all. Signals are generally different for self-defensive dogs versus those who are truly aggressive, as in competitive aggression.<ref name="frank" />
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.<ref name=tortora>Template:Cite journal</ref>
Predatory aggressionEdit
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.<ref name="frank" /> Predatory aggression is impacted by anxious influences, which results in the expression of affective aggression.<ref name="Chávez & Opazo 2012">Template:Cite journal</ref> This type of aggression is caused by sympathetic system activation and is non-affective.<ref name="Chávez & Opazo 2012" /> Based on a study that examines the predatory aggression in German shepherd dogs, this type of aggression is rarely displayed by dogs.<ref name="Chávez & Opazo 2012" /> However, if it does occur, it is usually directed towards unfamiliar dogs.<ref name="Chávez & Opazo 2012" /> Furthermore, predatory behavior activates reward centers in the central nervous system.<ref name="Chávez & Opazo 2012" /> According to Gonzalo and colleagues, this type of behavior is rewarding and therefore difficult to change.<ref name="Chávez & Opazo 2012" /> Predatory aggression is displayed by mature and intact males and this type of aggression results in serious damage to others.<ref name="Chávez & Opazo 2012" /> It includes actions such as chasing, biting, catching and may involve death or injury.<ref>Template:Cite thesis</ref>
Maternal aggressionEdit
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.<ref name=pmid31620484>Template:Cite journal</ref> Oxytocin plays an important role in the early bonding between the mother and her offspring.<ref name=pmid31620484/> Dogs with maternal aggressiveness are protective of their offspring and nest.<ref name=pmid31620484/> The change in hormone is linked to lactation, and the mothers can change the dogs' perception and assessment .<ref name=pmid31620484/> Maternal aggression may lead to bites or other attacks.<ref name=pmid31620484/> Maternal aggressiveness affects the growth and socialization of puppies.<ref name=pmid31620484/> Furthermore, this type of aggression may stem from unstable social environments.<ref name=pmid31620484/> 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.<ref name=pmid31620484/>
CausesEdit
Gut microbiomeEdit
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.<ref name=pmid30643689>Template:Cite journal</ref> The gut microbiome affects the affective disorders such as anxiety, which contribute to canine aggression.<ref name=pmid30643689/> Based on a study carried out by Kirchoff and colleagues, the composition of gut microbiome differs on the basis of aggressive and non-aggressive assessments.<ref name=pmid30643689/> In this study, the researchers tested rescued dogs that possessed aggressive and non aggressive behavior.<ref name=pmid30643689/> 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.<ref name=pmid30643689/> 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.<ref name=pmid30643689/> It also shows that the gut microbiome is associated with aggressive behavior.<ref name=pmid30643689/> Lactobacillus are present in the guts of dogs that exhibit aggressive behavior, even though strains of Lactobacillus rhamnosus reduce stress and anxiety in mice.<ref name=pmid30643689/> 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.<ref name=pmid30643689/>
AnxietyEdit
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.<ref name="frank" />
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.<ref name=pmid17916894>Template:Cite journal</ref> 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.<ref name=pmid17916894/>
FearEdit
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.<ref name="Tiira et al 2016">Template:Cite journal</ref> 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.<ref name="Tiira et al 2016"/> 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.<ref name="Tiira et al 2016"/> However, Abrantes points out that aggressive behavior in dogs is behavior that causes pain or injury,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and HSUS explains that barking and growling are normal communicative behaviors for dogs not necessarily indicative of aggression.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>
Breed, socialization, and health statusEdit
It is important to recognize that aggression is displayed more in certain breeds, which indicates the influence of genetic background on aggression in dogs.<ref name=pmid12854682/> According to Roll and Unshelm, German Shepherd dogs and Bull Terriers are more likely to display violent behavior to others.<ref name=pmid12854682/> Voith and Borchelt found that higher incidences of aggressive behavior were displayed in purebred dogs when compared with mixed breed dogs.<ref name=pmid12854682/> Often, aggression in adult dogs is usually a result of little to no contact in early life.<ref name=pmid12854682/> In other words, as a result of missed early socialization, a dog will not know how to interact with others, how to follow rules or how to adapt to new environments.<ref name=pmid12854682/> Aggressive behavior is more prominent in intact males when compared with neutered males and in sterilized females than intact females.<ref name=pmid12854682/> According to Hoerlein, the removal of a male's testicles has significant impact on aggressive and dominant males.<ref name=pmid12854682/> Neoplasia of the central nervous system, infectious diseases, developmental and metabolic disorders may impact aggression in dogs.<ref name=pmid12854682/> Many of these illnesses can cause aggressive and violent behavior, especially when located in the frontal cortex, the hypothalamus, the thalamus, the amygdaloid body, the medial mammillary, the nucleus, the habenular nuclei, the hippocampus and the caudate nucleus.<ref name=pmid12854682/>
ResearchEdit
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GonadectomyEdit
Gonadectomy is used to treat aggressive behavior of dogs. Farhoody and colleagues carried out a study to determine the impact of gonadectomy on the aggressive behavior of dogs using the Canine Behavioral Assessment Research Questionnaire (C-BARQ).<ref name=pmid29536014>Template:Cite journal</ref> According to the data collected, gonadectomized dogs between the ages of 7 and 12 months were more likely to be aggressive to strangers.<ref name=pmid29536014/>
Furthermore, gonadectomized dogs of all ages do not display violent behavior to familiar people or strangers.<ref name=pmid29536014/> The data does not show that gonadectomy prevent or treat aggressive behavior of dogs.<ref name=pmid29536014/>
Based on McMillan and colleagues’ research, aggressive behavior was prominent in dogs obtained from pet stores.<ref>Template:Cite journal</ref> Guy and colleagues found that environmental factors directly contributed to aggression in dogs.<ref name="Guy et al 2001">Template:Cite journal</ref> For instance, a dog that lives in a home with an adolescent or has a skin disorder is more likely to exhibit aggressive behavior to familiar people and strangers.<ref name="Guy et al 2001" />
Roll and Unshelm believed that the reason for buying or adopting a dog was a significant factor that correlated with aggression.<ref name="Roll & Unshelm 1997">Template:Cite journal</ref> They also argued that the relationship between the owner and dog determined whether or not the dog would exhibit aggressive behavior.<ref name="Roll & Unshelm 1997" /> For instance, the owner's attitude towards training, or physical mistreatment endured by the dog at the hands of the owner resulted in aggressive behavior towards others.<ref name="Roll & Unshelm 1997" /> Many factors impact the aggressive behavior displayed by dogs.<ref name="Roll & Unshelm 1997" />
Reactivity to stimuliEdit
According to Arata and colleagues, reactivity to stimuli is involved in various types of aggression.<ref name=pmid24972077/> The researchers used a questionnaire survey to assess approximately 5000 dogs of 17 breeds.<ref name=pmid24972077/> In this study, a factor analysis was used to extract five consistent factors in 14 of the 17 breeds.<ref name=pmid24972077/> Using 14 behavioral items, the researchers were able to see the consistent presence of these factors in dogs, indicating that these factors are linked to canine aggression.<ref name=pmid24972077/>
The collected data and the established factor system indicated that the French Bulldog, Cavalier King Charles Spaniel, Golden Retriever, and Labrador Retriever did not display aggressive behavior.<ref name=pmid24972077/> However, the Chihuahua and Miniature Dachshund were more aggressive and more likely to chase others.<ref name=pmid24972077/>
Based on this study, reactivity to stimuli was linked to owner-directed aggressive behavior in 13 different breeds, child-directed aggressive behavior in eight different breeds, stranger-directed aggressive behavior in nine breeds and dog-directed aggressive behavior in five breeds.<ref name=pmid24972077/> In this study, dogs that are highly reactive to stimuli were either uneasy and reacted to all movements or less engaged and overreacted to unexpected stimuli.<ref name=pmid24972077/>
The association between canine aggression and sociability with humans and likeliness to chase were examined.<ref name=pmid24972077/> Sociability with humans was linked to child-, stranger-, and dog-directed aggressive behavior in more than seven breeds.<ref name=pmid24972077/> Moreover, likeliness to chase was primarily linked to dog-directed aggressive behavior in 10 breeds and dogs that were more likely to chase smaller animals displayed aggressive behavior when interacting with other dogs.<ref name=pmid24972077/> Reactivity to stimuli was proven to be an underlying temperamental factor that leads to canine aggression.<ref name=pmid24972077/>
Other work has detailed how external stimuli significantly influences the experience of dog walking, sometimes “extracting a considerable social and emotional toll” for dog walkers.<ref>Template:Cite journal</ref>
TreatmentEdit
Treatment differs for each circumstance, and treatment plans are based heavily on the type of aggression.<ref name=Blackshaw1991>Template:Cite journal</ref> Based on Judith Blackshaw's study, dogs exhibited dominance aggression towards familiar people and therefore suggested obedience training as the proper treatment.<ref name=Blackshaw1991/> According to a study conducted in 1983 by Tortora, avoidance based aggression was treated by conditioning the dog to a safety tone, this resulted in a complete elimination of the aggressive behavior for the duration of the dogs lives.<ref name=tortora /> Aggression can also be reduced in adult dogs during their socialization period as a puppy. Studies show that exposing puppies to their new owners and homing before 8 weeks can drastically reduce aggression later in life.<ref>Template:Cite journal</ref> However, it is still imperative for an owner to train their dog every day for a minimum of 10 minutes.<ref name=Blackshaw1991/> More specifically, it is recommended for males to be neutered as this ensures that inherited aggression will not be passed on.<ref name=Blackshaw1991/> It is suggested to use synthetic progestins with castration to reduce and eliminate aggressive behavior in dogs.<ref name=Blackshaw1991/> Predatory and intermale aggression is inherent and related to testosterone secretion and as a result restrain, castration and the use of progestins are essential in reducing aggression in dogs.<ref name=Blackshaw1991/> Some studies suggest that aversive means of control and training contribute to new and increased aggression rather than reduce it.<ref name="Hsu & Sun 2010"/>