page header image

Chemistry shows dogs feel human-like emotions

Original Publication Date: January 25, 2016
By C. Sue Furman, Ph.D.

Any pet parent knows the joy that radiates from his dancing, tail-wagging dog whe he returns home from work.

Similarly, a human feels the love his dog expresses when he cuddles for pets.

Charles Darwin was one of the first to suggest that animals have emotions similar to those of humans. Scientists are now accumulating evidence to explain why.

Canine and human brains are quite similar. Both have a limbic system and similar neurochemistry that control emotions.

Neurotransmitters carry signals between neurons or nerve cells.

Excitatory neurotransmitters stimulate neurons that play a role in the "fight or flight" response. Inhibitory neurotransmitters decrease neuron activity and are associated with feelings of happiness and well-being.

Norepinephrine, epinephrine or adrenaline and cortisol are excitatory neurotransmitters that the adrenal gland sends out in times of fear or stress. These put the dog in the "fight or flight" mode. They cause his airways to open and his heart to pump harder to send more blood to major muscle groups. The dog must choose to stand his ground and fight or take flight and find safer territory.

Karen Overall of the Center for Neurobiology and Behavior at the University of Pennsylvania found that dogs with a history of aggressive or fight behaviors tend to have higher levels of the stress hormone cortisol in their blood than dogs with nonaggressive temperaments.

Similarly, dogs suffering from fear and anxiety register high levels of cortisol that encourage flight.

Serotonin and Gama-aminobutyric acid are inhibitory neurotransmitters. Serotonin is sometimes referred to as the feel good hormone, because it is responsible for feelings of happiness.

Vinny and da Princess share love with their momma Jackie Pinson Vinny and da Princess share love with their momma Jackie Pinson
(click image to enlarge)

Researchers at Zaragoza University in Spain found that aggressive dogs had lower levels of serotonin in their blood than nonaggressive dogs. Aggressive dogs apparently need a little more "feel good" hormone.

A dog develops more quickly than a human and his mind reaches its full emotional range by 4 to 6 months of age. His adult mind is roughly equivalent to that of a 21/2-year-old human. Both a toddler and a dog experience love, joy, fear, anger, excitement, contentment and distress.

A dog that soils the carpet while you are out may slink and cower upon your return home. Is he felling guilt and shame? Some believe he remembers being scolded for a similar misstep in the past and cowers out of fear that you will reprimand him again.

Some controversy continues concerning whether a dog experiences the full range of emotions that humans know.

Let the scientists wonder if your dog understands guilt and pride as we do. We know he feels love, joy, and contentment. Share these warm emotions with your favorite friend.

Sue Furman, Ph.D, has published two books and a DVD on canine massage and teaches classes in pet massage, acupressure, first aid and CPR. See her schedule and submit questions at