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Dogs become reactive mainly because of genetics or the influence of the environment in which they are raised, but most experts agree that it's a combination of the two. 

In order to better understand the making of a reactive dog, it therefore helps gaining a closer insight into how the dog's brain works and the impact of nature and nurture. Let's discover how nature and nurture intertwine in the making of a reactive dog.

The Nature or Nurture Debate 

The nature or nurture debate revolves around two different views. Is dog behavior the result of his genes (nature) or the environment in which the dog is raised (nurture)?

In general, when we think about genetics, we refer to the animal's brain pre-wiring as influenced by the dog's genetic inheritance. When a puppy is born, we assume that he will inherit from his mom and dad a tendency to be reactive or not along with other things such as coat color, eye color and size. 

However, after the puppy is born one cannot ignore the influence of external factors. The puppy may or may not become reactive based on the types of exposure, experiences and learning events the puppy undergoes as he matures. 

In the old days, the view that living beings acquired all or almost all of their behavioral traits as a result of the environment in which they were raised was referred to by John Locke in 1690 as "tabula rasa" a Latin term meaning "blank slate."

This "blank-slate" position which, was all based on experiences, denying the influence of heritability, clashed against the view admitting both environmental and heritable traits, paving the path for the famous "nature and nurture debate" an ideological dispute that took place throughout the second half of the 20th century.

The debate was finally sorted out with both "nature" and "nurture" factors being found to contribute substantially, although in an inextricable manner, in the development of behavior. 

No heredity. No environment. Only the interaction between the two.”~Robert Sapolsky

Fearful behaviors may be inherited

Fearful behaviors may be inherited

A Matter of Genes 

Genes can certainly play a role in a dog's propensity for reactivity. Specific abnormalities in the brain can be passed down from a generation to another. These abnormalities may appear in many dogs as an accident or anomaly.

Knowledgeable breeders can attempt to breed out a strong tendency to being reactive by strategically breeding only dogs who have shown to develop non-reactive behaviors into adulthood. 

Problems start though when breeders don't know how to exclude abnormally reactive dogs from their breeding stock, or breeders purposely aim on creating lineages that reliably exhibit reactive behaviors. 

Hence, the importance of purchasing dogs from reputable breeders who selectively breed for health and stable temperaments. 

Did you know? According to a study, it took only took 5 generations to obtain lines of dogs that were more nervous than usual. These dogs were shy, less active, less curious and sometimes catatonic when approached by people (Source: Murphree et al. 1974).

The Impact of the Environment 

As mentioned, the environment in which a dog is raised substantially contributes to his reactivity. What may happen though in a dog's environment to stimulate a dog to react this way? Why are dogs lunging and barking at triggers?

Well, things can start taking place as early as when the puppy is still in the womb.  Studies have shown that, if mother dog is stressed, her stress hormones cross the placenta impacting a developing fetus. 

With such a "chemical bath", the puppy learns that the world must be an unpredictable place, and therefore develops a predisposition for being hyper vigilant and potentially reactive. Discover more about this fascinating phenomenon here: can mother dog's stress impact her puppies?

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Once born and weaned, the environment may further have an impact. According to a study (Pierantoni et al., 2011 ), puppies removed too early from the litter was a significant predictor for excessive barking, fearfulness on walks and reactivity to noises.

Inadequate socialization may also play a role. Lacking quality exposure that helps inoculate from developing fear-based aggression, a puppy soon learns that the unknown is intimidating. 

Perhaps the puppy or dog is also exposed to situations that are perceived as frightening. Fear periods, when not tackled correctly, may also have an impact and so can moving to a rural area, leading to what is known as "suburban dog syndrome."

The Impact of Reinforcing Consequences 

Next, add the inherent reinforcing nature of acting reactive. The dog barks and lunges? The person or other dog likely moves away, leading to the dog getting a sense of relief. 

This relief is reinforcing to the dog. Lunging and barking in this case is a distance-increasing behavior, meaning that the dog is asking for space. 

The behavior of acting reactive therefore puts roots and establishes. The more the dog rehearses the reactive behavior, the more it repeats and becomes almost an automatic default behavior upon noticing triggers. 

Did you know? Sometimes dogs who act reactive, are in reality dogs who are eager to meet other people and dogs. 

This form of reactivity takes place when these dogs are so eager to meet and greet that they get strongly frustrated because restrained by the leash and the arousal soon spills into an aggressive display.

 Off-leash, these dogs are social butterflies, playing with other dogs and/or acting super friendly towards people. 

Many cases of reactivity start during social maturity.

Many cases of reactivity start during social maturity.

Changes During Social Maturity 

It may not be a coincidence if Rover starts getting more and more reactive as he matures. Social maturity in dogs in general starts around 9 to 10 months up to 1-2 years of age and generally lasts up to 36 months (in large breeds mostly).

 During this time, behavior problems seem to peak somewhere between 12 to 18 months of age. Of course, there are individualized variations in these time frames based on dog breed and size. 

Data from research has shown that, many pets develop problems at social maturity. This is a major contributing factor as to why many dog owners give up their pets at around one and a half years old (Salman et al., 2000 ). 

Veterinary behaviorist Dr. Karen Overall in the book Manual of Clinical Behavioral Medicine, attributes the onset of problems during social maturity to myelination and regressive pruning taking place during this time at a neurochemical level.

 In simple words, this is a time of significant developmental changes in the brain. In particular, this is a time of the formation of neuro-behavioral developmental patterns with the frontal cortex being particularly involved in the regulation of “emotion” and emotional outbursts. Something to certainly keep in mind!

Other Considerations

In some cases, dogs may become more reactive because of something going on physically or at a chemical level. A sudden onset of reactive behavior in a dog who was never that way should raise a red flag. 

 For example, a dog who is getting older may not longer see or hear well, and this may trigger reactive behavior from being startled. Some dogs who get reactive may have low thyroid levels, low glucose levels of they may be suffering from pain, to just name a few factors. 

Now That You Know...

Now that you are aware of why dogs may become reactive, you may be wondering what you can do to work on the problem. Can a reactive dog be cured? In general, the earlier you tackle the issue, the better. Nipping reactive behaviors in the bud is therefore important so to prevent them from establishing. 

  • Skip punishment-based methods. This means no yelling, no alpha-rolling, no use of aversion-based training tools such as choke chains, prong collars and shock collars. These tools and methods only risk aggravating your dog's anxiety, exacerbating his reactivity.
  • Prevent rehearsal of the problem behavior. Th more your dog rehearses the barking and lunging behavior, the more it establishes and becomes habit-forming. Consider that if your dog is too reactive or hypervigilant on walks, stress hormones will flood his body and this stress will carry over to the home increasing potential reactivity to things. And vice-versa, if it's stressful at home, that stress will be carried over to walks. So it's important to carefully manage things on walks and indoors, to prevent them from becoming too stressful events. 
  • Keep your dog under threshold. Often, distance can make a big difference. Make sure you walk your dog at a distance from his triggers. 
  • Invest in  no-pull, front-attachment harness. This harness has a ring to which you attack the leash, allowing you better control than a regular collar. 
  • Train the emergency u-turn. If you notice a dog or person coming too close for comfort, make an about-turn so that your dog doesn't get too stressed. 
  • Invest in high-value treats. Skip kibble or stale cookies. To work on reactivity, you need super high-value treats. 
  • Create positive associations. From a safe distance, feed your dog high-value treats every time he sees a trigger. The "look at that dog" exercise can turn helpful. 
  • Train attention-heeling. Once your dog reliably looks at the trigger  and then at you for a treat, train your dog to perform the behavior as you are walking. 
  • Invest in calming aids. Highly-stressed dogs may benefit from calming products such as calming supplements, DAP collars, Thundershirts or Calming Caps. Some dogs may need prescription medications. Consult with your vet. 
  • Enlist the help of a professional dog trainer or behavior consultant using force-free training and behavior modification. He or she can confirm that your dog is truly reactive and not acting out because of other differentials such as protective behavior or barrier frustration, and can help you implement behavior modification correctly while keeping the safety of you, your dog and others around you in mind. 
  • Look for Reactive Rover classes. These are special classes run by dog trainers that tackle dog-to-dog reactivity. 
  • See your vet to rule out medical causes of reactivity in dogs. 

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