Dog Brain Chemistry and the Use of Medications and Behavior Modification

Dog aggression brain chemistry
Dog aggression brain chemistry

The Role of Chemical Imbalances in Dog Behavioral Problems

If you own an aggressive or fearful dog, you may be wondering what may trigger those bouts of aggressive or anxious displays you witness and how medications may play a role in the recovery process. Just as in humans, chemical imbalances may take place in your dog's brain and can play a primary role in the behavior of your dog. Taking a look at your dog's brain chemistry may be helpful in many cases. Let's take a virtual walk into your dog's brain so to have a generalized sense of what may be possbily going on in there.


What's in Your Dog's Brain and How Does it Affect his Behavior?

The brain of dogs are ultimately quite similar to the brain of humans in many ways. They both include a limbic system which is where emotions and memories are stored. Also, both brains share the same basic neural chemistry, explains Stanley Coren. This means that just as humans, dogs may suffer from emotional problems such as anxiety, fear and anger. This paves the path to behavioral problems such as depression, stress-related disorders, irrational fears and compulsive, obsessive disorders.

A first step is to understand the role of neurotransmitters. Neurotransmitters are basically chemical messengers responsible for carrying, boosting and modulating signals between neurons . There are two types of neurotransmitters:

  1. Excitatory neurotransmitters: which excite the neuron, stimulating it to action. Examples are norepinephrine, epinephrine -aka adrenaline- and cortisol which are fight and flight hormones produced by the adrenal gland.
  2. Inhibitory neurotransmitters: which inhibit the neuron, decreasing its action. Examples are: serotonin and GABA.
  3. Excitatory and inhibitory neurotransmitters: can have both effects depending on the receptors, Examples are acetylcholine and dopamine.

Excitatory Neurotransmitters

Let's take a closer look into these neurotransmitters and their role in canine behavior.

  • Epinephrine

Also known as adrenaline, epinephrine along with norepinephrine and cortisol participates in the flight and fight response by making your dog's heart pump harder, opening the airways, and increasing blood flow to major muscle groups in response to a threat.

  • Norepinephrine

Along with epinephrine and cortisol, norepinephrine is a stimulant and partecipates in the fight-or-flight response, by increasing your dog's heart rate. At the same time, norepinephrine is also, a mood enhancer which explains why along with serotonin, norepinephrine has a positive effect in the brain which enhances mood.

  • Cortisol

This steroid hormone is also released in response to stress along with norepinephrine, epinephrine. When a dog gets into "flight or fight" mode, this chemical is often released and this is why it is often referred to as the "stress hormone". Karen Overall of the Center for Neurobiology and Behavior at the University of Pennsylvania found that aggressive dogs displayed an increased level of cortisol in their blood and in a similar fashion did dogs who were fearful and anxious. A study determined that aggressive dogs had 21 units compared to 10 in non-aggressive dogs.

Inhibitory Neurotransmitters

  • Serotonin

This is a neurotransmitter found in the intestinal tract and central nervous system. This chemical is thought for being responsible for general feelings of happiness and well being which is why it is often referred to as the "feel good" hormone. A study by researchers at Zaragoza University, in Spain determined that dogs that were aggressive had lower levels of serotonin in their blood. To be exact, such dogs had 278 units compared to 387 in non-aggressive dogs.

Serotonin, unfortunately cannot be supplied under the form of a pill or injection. Interestingly though, a class of drugs known as tricyclic antidepressants (TCA) helps slow down the reabsorption rate of the neurotransmitters serotonin and norepinephrine allowing their levels to rise. A drug belonging to this class is clomipramine.

On the other hand, another class of drugs known as “selective serotonin reuptake inhibitor," often abbreviated as SSRI, helps block the reabsorption of serotonin allowing more serotonin to be available for extended periods of time, explains Certified Applied Animal Behaviorist, Benjamin L. Hart . Drugs belonging to this class include fluoxetine, sertraline and paroxetine.

*Note: Buspirone is a serotonin 5-HT Agonist known for activating serotonin receptors, and mimicking the effect of serotonin.

  • GABA

GABA stands for Gamma-aminobutyric acid which is a neurotransmittor responsible for regulating neural excitability.Benzodiazepines help enhance the effect of this neurotransmitter, reducing the firing rate of neurons in the central nervous system.

Excitatory and Inhibitory Neurotransmitters

  • Dopamine

"Dopamine helps coordinate the dog's motor skills, attention, reinforcement and reaction time and it has an impact on the brain’s mood area where “good feelings” originate" explains dog trainer Nicki Tudge. When neurotransmitters transfer excessive dopamine dogs can become agitated, impulsive and easily reactive creating an excitatory response. On the other paw, when dopamine levels are reduced the dog becomes under reactive crating an inhibitory response.

  • Acetylcholine

This neurotransmitter at a cardiac level has an inhibitory effect, which lowers heart rate. However, acetylcholine, may also behave as an excitatory neurotransmitter at the neuromuscular level in skeletal muscles.



What Medications are Usually Used in Dogs for Behavioral Problems?

The most common class of drugs used in behavior modification are: benzodiazepines (BZs), monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs), according to the ASPCA.These medications may be prescribed by a veterinarian or board certified veterinary behaviorist.


  • Acetylpromazine (Acepromazine)
  • Alprazolam (Xanax) BZ
  • Amitriptyline (Elavil) TCA
  • Buspirone (Buspar) serotonin 5-HT Agonist
  • Fluoxetine (Reconcile, Prozac) SSRI
  • Clomipramine (Clomicalm) TCA
  • Diazepam (Valium) BZ
  • Paroxetine (Paxil) SSRI
  • Propranolol (Inderal)
  • Selegiline (Deprenyl, Anipryl) MAOI's
  • Sertaline (Zoloft) SSRI

So do Medications Help Dogs?

While behavior modification alone may help dogs in need and change emotions and brain chemistry, it is also true that in certain severe cases, medications may be needed so to stop the brain from interfering with learning appropriate behavior. Following are some benefits and reasons why medications may be needed in severe cases:

  1. When your dog is in a fight or flight state of mind, he is ready to react and not capable of learning. With medication, your dog will be calmer and has better chances for learning.
  2. Medications may speed up the learning process.
  3. Some medications such as benzodiazepins act quickly if given before exposure.

However, there are also cases where the use of medications, is counter-productive and there are also disadvantages. Followings are some of the cons:

  1. There are risks for side effects and paradoxical effects.
  2. As the dog is weaned off the medication there may be relapses.
  3. Most medications are not a quick fix, may need to be taken for a while before effects are seen
  4. Medications should not be used alone; but rather, along with a behavior modification program.

My Experience with Medications versus Behavior Modification

While I am not a big fan of meds, in my opinion, I think in severe cases and in certain dogs they do help take the edge off (by fixing imbalances in neurotransmitters) so to open up the lines for learning so the dog can cognitively function. And this is a good reason why vets should refer clients to trainers/behavior consultants so the vet can take care of chemical imbalances and the trainer/behavior consultant can handle the behavior modification process. This partnership should help prevent veterinarians from unnecessarily increasing dosages and owners becoming frustrated because the "meds are not working".And in some cases, the dog may even not need any meds at all, because the trainer/behavior consultant may have alternative approaches/calming aids/methods up their sleeves.

I worked on a case with a behaviorist where the dog had interdog aggression and the drugs were needed because according to the behaviorist the dog was reactive no matter the distance. I had my doubts on this though. The fact is, this dog was in a fenced area with the other dog at a distance in a separated fenced area. It seemed to me the drugs were perhaps needed to make him comfortable and work sub-threshold in "THAT setting". If I had this case on my own, I would have been curious to know if in a different setting and with more distance it was possible to find a threshold "oasis" without the need of drugs.

A while back, I was called to work on a case of severe inter-dog aggression where the dog was not walked for over a year in a neighborhood surrounded by fenced dogs. There was little opportunity to find a comfortable threshold distance here because of how the neighborhood was displayed. It took weeks of daily work to get to the point of walking him past the dogs without reacting, but we finally made it. So in my experience, drugs can make the process easier and perhaps even shorten it, but I am not a big fan of them when vets prescribe them because of obvious risks for side-effects and the fact that once the dog is weaned off, I have seen relapses (just as in people), whereas with no drugs, the process took longer but the results seemed to me more reliable, at least in my humble opinion.

What do studies says? "Drug therapy is rarely curative by itself and in most cases is only indicated as ancillary therapy in a behavior modification program" according to this abstract.

Alexadry © all rights reserved, do not copy.

What's your take on meds and behavior modification for dogs?

  • I think they both work best hand-in-hand and are both essential.
  • I prefer meds alone; don't have time to work on my dog's issues.
  • I rather not use drugs.
  • Meds only for severe cases, along with behavior modification.
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Comments 7 comments

Larry Fields profile image

Larry Fields 4 years ago from Northern California

Hi Alexadry. Loved your hub.

I used to take my neighbor's family's Border Collie mix on day hikes. I found that a home-made 'treat', consisting mainly of Carob powder and butter-flavored Crisco, had a slight calming effect on Gurr. When we stopped to eat lunch, he would get that for 'dessert', after a handful of his regular kibble. Milk Bone dog biscuits had the opposite effect. Go figure.

Voted up and interesting.


alexadry profile image

alexadry 4 years ago from USA Author

Thank you. Studies have shown that diet can have a calming effect on dogs. One study suggests that tryptophan helps dogs suffering from aggression and hyperactivity. This makes sense, since trytophan is know for causing sleepiness in humans after drinking milk or eating chicken/turkey along with a carbohydrate snack.


mary615 profile image

mary615 4 years ago from Florida

As always, you have written a very informative Hub. You are certainly an expert in canines and their behaviors. I've never had an aggressive dog, thank goodness.

My Miniature Schnauzer is an easy going dog for the most part.

I voted this Hub UP, etc. and I will share this good info.


Nat Amaral profile image

Nat Amaral 4 years ago from BC Canada

I love this hub. Yes, I think there should be treatment for the aggressive dog behavior because of some past experiences (bitten by 2 different dogs on 2 different occasions), but that should be done with some caution. Every dog will respond to it differently, and in some cases, it won't always be good.


alexadry profile image

alexadry 4 years ago from USA Author

Thanks Mary, I am studying to further continue my education (this time specializing in getting a canine psychology degree), so you will see more and more articles tackling dog behavior for some time!


alexadry profile image

alexadry 4 years ago from USA Author

Nat Amaral, I agree dogs should get an individualized treatment plan since they all respond differently to treatment. The one size fits all definitely does not apply here.


annerivendell profile image

annerivendell 4 years ago from Dublin, Ireland

Another great hub. What an interesting area too! Voted up.

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    alexadry profile image

    Adrienne Janet Farricelli (alexadry)1,689 Followers
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    Adrienne Farricelli is a former veterinary hospital assistant and now a certified dog trainer, behavior consultant, and author of dog books.



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