Saluki Health

Breeder's Notebook: The Fear Factor

D. Caroline Coile, Ph.D.

This article appears with permission of the author

 

The dog cowered behind his owner. “He was abused before we got him,” the owner explained. Maybe — but maybe not. Sometimes shy dogs are shy because that’s how they were born.

The genetics of dog behavior related to shyness has a long experimental history. In the 1930s Charles Stockard undertook a massive research project in which he compared several breeds and their crosses on behavioral tests and endocrine measures. Stockard documented breed differences in many behaviors including excitability and reactivity. In the process he inadvertently created a number of shy dogs, and upon investigation he found they had one thing in common: they all descended from one shy Basset Hound.

After Stockard’s death, canine behavioral genetics fell to Fuller and Scott, who also documented breed differences in reactivity. However, they did not pursue the question of shyness. Only in the 1970s was hereditary shyness in dogs examined in depth. Starting with both normal and unusually nervous Pointers, O.D. Murphree and colleagues selectively bred the nervous dogs to one another. Now Karen Overall and Greg Acland study these dogs’ descendents. The difference in behavior of the nervous and normal dogs is compelling. When placed in a new setting, the nervous dogs do not attempt to explore. When a loud noise is made, they freeze. When approached by a human, they become rigid, trembling when stroked, avoiding eye contact. They remain rigid even after the person leaves them. Afterward they have high levels of cortisol, a hormone associated with stress. In contrast, the normal Pointers raised in the same environment—in fact, often cross-fostered so that shy foster mothers raise genetically normal pups and normal foster mothers raise genetically shy pups—are eager for human interaction and new experiences. Their cortisol levels are much lower than their nervous kennelmates’.

More recently, a line of shy Siberian Huskies has become the focus of research. The Husky line began with a shy male named Earl; unlike the nervous Pointers, the shy Huskies move away from strangers rather than freeze; they also eventually become comfortable with a single caretaker, something the nervous Pointers never do.

In both the Pointers and Huskies, not every dog in every litter is affected. Many litters have both nervous and normal siblings. Nor is every nervous dog affected to the same extent. Researchers postulate that these degrees of nervousness may be exaggerated expressions of traits that are components of the breed’s function: the Pointer’s freezing on point in response to a stimulus and the Husky’s social deference of a cooperative sled dog.

These dogs are not just of interest to breeders, but to researchers studying panic disorder in humans because the fearful dogs and humans share several similarities. For example, humans with panic disorder respond to intravenous administration of sodium lactate with feelings of panic. The nervous Pointers and shy Huskies also respond to lactate administration with signs of extreme anxiety, suggesting that the same neurochemistry may be behind the behaviors.

It’s likely that the same neurochemistry and brain structures are associated with fearful behavior in both humans and dogs. Primitive structures of the brain are similar in both dogs and people. One such structure, the amygdala, is thought to coordinate the body’s fear response, and has shown abnormal activity associated with anxiety disorders.  Other studies have shown increased activity in structures of the brain (the hippocampus and locus coeruleus) that modulate the brain’s responses to stimuli. People with panic disorder have also been found to have abnormal receptors for certain anxiety-reducing chemicals within the brain. Fearful behavior in dogs or humans may arise from several different genes that act on brain structures or neurochemistry in slightly different ways.

These studies have shown you can select for shyness; what about selecting against shyness? One of the most intensive behavioral genetic experiments in canids began in Siberia in 1959, and still carries on today. Dmitry Belyaev and colleagues rigorously selected for tameness in silver foxes. After 35 generations (and 75,000 foxes) they achieved a line of “domesticated elite” foxes, in which about 75% actively elicit human interaction. Compared to the wild stock, these friendly foxes don’t become fearful until later in their development, and they also don’t have a rise in cortisol levels until later. Even then their cortisol levels are roughly half that in wild foxes. The friendly foxes’ brains contain higher levels of serotonin, a neurotransmitter associated with behavior. Interestingly, several of the friendly foxes have shown physical characteristics such as white hair patches, drooping ears, and curled tails otherwise seen in domestic animals.  This has led to speculation that selecting for tameness may inadvertently also select for physical traits that may be either linked to certain mutations for tameness or direct effects of mutations for tameness.

Domestic dogs, by definition, have already undergone such selection for tameness, one component of which is probably boldness. Some degree of fearfulness is adaptive, but the optimal degree depends on an animal’s circumstances. A continuum of boldness to shyness is found within wolves and within dogs.

Some breeds have higher percentages of bolder versus shyer individuals. Scandinavian researchers Kenth Svartberg and Bjorn Forkman analyzed the results of standardized behavioral tests given to 15,329 dogs of 164 breeds. They identified four basic personality traits (playfulness, curiosity/fearlessness, chase-proneness, and sociability) that taken together form a broad shyness-boldness continuum. Considering only the 31 breeds in which there were scores for at least 40 dogs, the Flat-coated Retriever, Labrador Retriever, and Belgian Malinois were ranked boldest; the pinscher, smooth Collie, and Rhodesian Ridgeback were the shyest. The bold dogs are easier to train as working dogs, regardless of task, but they aren’t always the best choice for pets because a certain amount of caution can be advantageous.

Breeders can select for shyness or for boldness, but environment also has considerable influence. Nervous Pointers trained alongside normal Pointers, especially when trained for field work, improved significantly. And even a dog from the boldest background will never be bold if he doesn’t receive early socialization. Every dog’s temperament is a reflection of its genetic heritage and experience. Not every shy dog has been abused, and not every abused dog is shy.

Copyright © 2007 Saluki Club of America.