Your dog might not remember exactly what kind of treat you fed him yesterday or what color of shirt you were wearing, but if you were to ask him precisely where he was when he heard a loud noise and startled, he would likely be able to identify the exact location. When it comes to recollecting stressful and scary events, dogs seem to have the uncanny ability to remember quite well. Owners of dogs suffering from noise phobias know this too well, all it takes is a loud noise for their dog to activate all sorts of avoidance behaviors when they encounter the same area again. As much as this sounds like a bad thing, the fact that fear sinks in deeps, is survival instinct working at best.
The Power of Stress
During times of stress, the dog's body is bombarded with the release of stress hormones into the bloodstream. These hormones and all their associated physiological changes are there for a good reason: to up the dog's chances for survival.
The dog's heart rate and breathing increase, his senses are amplified, the ears are ready to capture the slightest sounds and the pupils dilate so Rover can see with more clarity.
At the same time, muscles receive increased blood flow so that the dog can sprint into action, blood pressure increases, a surge in blood sugar released from the kidneys provides a boost of energy and a dog's appetite is suppressed as blood flows away from the digestive tract to the muscles for action (try dangling a slice of baloney in the face of a terrified dog).
Several changes also take place at a mental level. Dogs who are stressed and frightened, often have a hard time concentrating, their impulse control and bite threshold may lower. When it comes to memory though, the ability to recall the event seems to sharpen.
Everlasting Bad Memories
Ask anybody what they were doing on September 11th 2001, and most people will have a clear recollection. " I was stacking supplies at the store" or "I was eating lunch with a friend" or "I was playing soccer when my sister called me and gave me the news."
Then ask anybody what they were doing a week ago at this same exact time, and they'll likely give you a blank stare. It is natural for people and animals to remember bad episodes, especially when they are situations that had a strong emotional impact or that could have hurt somebody significantly.
It makes sense for stress hormones to help recollect memories of events that take place when we're undergoing stress, explains Roger Abrantes, PhD in Evolutionary Biology and Ethology and director at the Ethology Institute Cambridge where he holds regular lectures.
"We cannot know what dogs "perceive," but we do know that dogs have excellent memories and the same brain architecture and functions as humans do, so when we see behaviors consistent with true panic, even if the stimuli are not present, we need to consider that memory of these stimuli... could be what is distressing the dog."~ Karen Overall.
Fear Through Generations
Interestingly, fearful responses to certain stimuli may be even passed from a generation to another.
In a study published in the Journal of Nature Neuroscience, rats were given an electric shock each time they were presented with acetophenone, a compound that gives off a scent resembling cherry blossoms.
Shock after shock, the rats soon becomes sensitized to the the scent resembling cherry blossoms and they would show a fearful response.
After being bred, these rats gave birth to offspring who, without any prior conditioning (learning) showed fearful responses to the scent despite never having witnessed it before.
This demonstrates that it is possible to pass down fear of a smell even in several generations, which makes evolutionary sense if you think about it, since teaching future generations to recognize the scent of dangers, can up the chances for survival. This is quite fascinating, and surely more studies are needed on this to understand the exact dynamics.
Did you know? When an intensely unpleasant or aversive event leads to a dog developing a fearful lasting memory, it's known as "one-event learning," explain Gary M. Landsberg, Wayne L. Hunthausen and Lowell J. Ackerman in the book "Behavior Problems of the Dog and Cat."
- Parental olfactory experience influences behavior and neural structure in subsequent generations, by Brian G Dias & Kerry J Ressler, Nature Neuroscience17,89–96(2014)
- "How epigenetic memory is passed through generations: Sperm and eggs transmit memory of gene repression to embryos."University of California - Santa Cruz. ScienceDaily. ScienceDaily, 18 September 2014.
- Ethology Institute of Cambridge, Bonding and Stress, by Roger Abrantes, retrieved from the web on July 29th, 2016
- Manual of Clinical Behavioral Medicine for Dogs and Cats, By Karen Overall, Mosby; 1 Pap/DVD edition (July 9, 2013)
- Behavior Problems of the Dog and Cat3: Behavior Problems of the Dog and Cat, By Gary M. Landsberg, Wayne L. Hunthausen, Lowell J. Ackerman, Saunders Ltd.; 3 edition (December 28, 2012)