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Aggression in dogs is the most prevalent and significant behavioral issue. It is the primary reason why pet owners seek assistance from behaviorists, trainers, and veterinarians.

Understanding Aggression:

Aggression encompasses a wide range of behaviors that occur in various circumstances for different reasons. Most wild animals exhibit aggression when protecting their territories, offspring, and themselves. Similarly, social animals like humans and dogs employ aggression or the threat of aggression to maintain social order and negotiate interactions.

The term "aggressive" in reference to a dog can encompass a multitude of behaviors. Aggression involves a series of escalating actions, starting with warning signs and potentially leading to an attack. Dogs can terminate their aggressive behavior at any point during an encounter. 

A dog exhibiting aggression towards people typically follows a sequence of increasingly intense behaviors:

  • Becoming motionless and rigid.

  • Emitting a deep, threatening bark.

  • Lunging or charging at the person without making physical contact.

  • Using their mouth to control or manipulate the person without applying significant pressure.

  • Delivering a "muzzle punch" by striking the person with their nose.

  • Growling.

  • Displaying teeth.

  • Snarling (a combination of growling and showing teeth).

  • Snapping.

  • Nipping quickly without leaving a mark.

  • Biting with enough force to break the skin or cause a bruise.

  • Inflicting puncture wounds.

  • Repeated bites in rapid succession.

  • Biting and shaking.

Dogs do not always strictly adhere to this sequence, often exhibiting multiple behaviors simultaneously. Pet owners often fail to recognize the warning signs preceding a bite, perceiving their dogs as suddenly becoming aggressive. However, there is usually a brief period between the warning and the actual bite, although it can be a matter of milliseconds.

Classification of Aggressive Behavior:

To comprehend why a dog displays aggression, it is helpful to classify aggressive behaviors based on their purpose or function. This classification can aid in identifying the underlying motivations and desired outcomes associated with the aggression. 

The following are some common categories of aggressive behavior in dogs:

Territorial Aggression

Dogs attack and bite intruders, regardless of whether they are friendly or hostile.

Protective Aggression

Dogs exhibit aggression when they perceive a threat to their family members or friends.

Possessive Aggression

Many dogs display aggression when guarding their possessions, even if it is unnecessary.

Fear Aggression

 Fearful dogs may become aggressive when they feel cornered or trapped.

Defensive Aggression

Motivated by fear, defensively aggressive dogs believe that offense is their best defense.

Social Aggression

Dogs that perceive themselves as dominant may show aggression toward family members.

Frustration-Elicited Aggression

 Dogs excited or aroused by something but prevented from approaching it may become aggressive.

Redirected Aggression

Occurs when a dog displays aggression towards a person or animal, but someone else interferes.

Pain-Elicited Aggression

Normally friendly dogs can exhibit aggression when in pain.

Sex-Related Aggression

Intact male dogs compete for female attention, and females compete for access to males.

Predatory Aggression

Some dogs exhibit classic predatory behaviors, such as chasing and grabbing fast-moving objects.

Aggression Towards Individuals and Triggers:

Understanding the specific targets of a dog's aggression is crucial for comprehending their behavior. It is common for dogs to display aggression towards unfamiliar people, with studies reporting that a significant percentage of pet dogs exhibit threatening barking and unfriendly behavior towards strangers. Aggression towards unfamiliar dogs is also widespread. However, aggression towards family members or other pets in the household is less common. Aggression towards children, especially within the family, poses significant challenges and safety concerns. Dogs displaying this problem are difficult to treat, and their potential for becoming trustworthy is low.

Some dogs exhibit aggression only towards specific categories of individuals. For instance, a dog may be aggressive solely towards veterinarians, postal carriers, or individuals with disabilities. In some cases, limiting the dog's access to the individuals that trigger their aggression is feasible. However, in other scenarios, such as living in a densely populated area with unavoidable exposure to children, managing the dog's aggression becomes more challenging.

Risk Factors:

When deciding to live with and treat an aggressive dog, several factors should be considered. As a responsible pet owner, you are ultimately accountable for your dog's behavior. These factors include the level of risk associated with living with the dog and the likelihood of behavior change:

  • Size. Regardless of other factors, larger dogs can be more intimidating and cause greater harm than smaller dogs.

  • Age. Young dogs with aggression problems are generally considered more adaptable and easier to treat than older dogs.

  • Bite history. Dogs that have previously bitten are known risks and can create insurance liabilities.

  • Severity. Dogs that stop their aggression at displaying teeth, growling, or snapping are safer to live with than dogs that bite. Dogs causing minor injuries, like bruises, scratches, or small punctures, are less risky than those inflicting serious wounds.

  • Predictability. Dogs with inconsistent and unpredictable aggression, biting without warning, are at higher risk of being euthanized. Dogs that give warning signals before biting provide others the opportunity to retreat and avoid harm.

  • Targets. The frequency of exposure to the targets of aggression affects the manageability and resolution of the behavior. For example, a dog aggressive towards strangers is easier to control in a rural setting with a securely fenced yard. Aggression towards children can be managed if the dog's owners are childless or have no contact with children. Aggression towards unfamiliar dogs poses less difficulty for owners who avoid dog parks and opt for isolated hiking trails. Conversely, living with a dog that bites family members while trying to administer medication during recurring ear infections can be stressful and unpleasant.

  • Triggers. Assessing whether the circumstances prompting aggression can be avoided is essential. If a dog guards its food only while eating, the solution is simple: refrain from approaching during meals. However, if the dog prevents anyone from safely entering the kitchen due to guarding an empty food bowl in the cupboard, the situation becomes more complicated. Dogs that bite any reachable stranger pose a greater danger than those who only bite strangers attempting to kiss them.

  • Ease of motivating your dog. The ease of motivating a dog during retraining is another consideration. The safest and most effective approach to treating aggression involves behavior modification guided by a qualified professional. Successful behavior modification typically involves rewarding the dog for good behavior, so dogs that respond well to praise, treats, and toys are more likely to improve. Dogs with low motivation for these rewards can pose additional challenges, and the likelihood of improvement is diminished.

Collaborating with a Veterinarian and Professional Behavior Expert:

Some aggressive behaviors in dogs stem from medical conditions or complications. Apart from acute painful conditions, dogs with orthopedic problems, thyroid abnormalities, adrenal dysfunction, cognitive dysfunction, seizure disorders, and sensory deficits may exhibit increased irritability and aggression. Geriatric dogs can experience confusion and insecurity, leading to aggressive behavior. Certain medications and diet can also impact a dog's mood and susceptibility to aggression. It is crucial to consult with a veterinarian to rule out any underlying medical issues that may contribute to or worsen the dog's behavior. If a medical problem is discovered, close collaboration with the veterinarian is necessary for the best chance of improvement.

Addressing aggression requires the expertise of a professional behavior expert. Aggression is a complex behavior problem to diagnose and treat, and inappropriate application of behavior modification techniques can have negative consequences. Even experienced professionals may encounter occasional bites when working with aggressive dogs. Therefore, living with and treating an aggressive dog inherently carries risks. A qualified behavior expert can develop a customized treatment plan based on the dog's temperament and the family's unique circumstances. They can guide the implementation of the plan, monitor progress, and make necessary adjustments. In cases where a dog's quality of life is severely compromised or the risks of living with the dog are too high, the behavior expert can help make the difficult decision of whether euthanasia is warranted. When seeking the assistance of a Certified Professional Dog Trainer (CPDT), ensure they possess the necessary education and experience in treating canine aggression, as this expertise is not required for CPDT certification.

Can Aggression Be Cured?

Pet owners often wonder if their aggressive dog can ever be fully "cured." Based on current understanding, the incidence and frequency of certain types of aggression can be reduced and sometimes eliminated through behavior modification techniques. However, complete eradication of aggression is not guaranteed. In many cases, managing the problem by minimizing the dog's exposure to triggering situations, individuals, or objects is the only viable solution. Dealing with an aggressive dog always carries inherent risks, and pet owners must take precautions to prevent harm to others. Even if a dog has exhibited good behavior for an extended period, it is impossible to predict when circumstances might align to trigger their aggression. Dogs that have a history of using aggression as a coping mechanism in stressful situations may revert to that strategy. Therefore, pet owners should remain vigilant and never assume that their dog is permanently "cured."

Are Some Breeds More Aggressive Than Others?

While certain breeds may have higher statistics of biting and aggression, it is important not to judge a dog solely based on its breed. Various factors contribute to breed-specific tendencies, including the historical functions and traits associated with specific breeds. Although modern pet dogs of these breeds may no longer perform their original tasks, they may still retain genetic predispositions toward certain types of aggression. Nevertheless, individual temperament and a dog's history of interactions with people and other animals are better predictors of aggressive behavior than breed alone. When selecting a dog, it is advisable to research breeds thoroughly to ensure compatibility with one's lifestyle. However, the most reliable way to prevent aggression problems is to choose an individual dog with a suitable temperament for the owner's circumstances.

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