Fear and Stress Disorders in Animals.

Fearfulness (or timidity) is a personality trait with both learned and genetic elements. Thus, some lines of animals have an innate tendency to be easily startled, or even to have a full blown metabolic response that might be considered similar to a panic attack. Generally the longer a breed has been domesticated the less fearful they will become. But highly selective breeding can propagate mutations that predispose animals to be fearful. A few examples are discussed below.

Cattle

In cattle some breeds such as Brahman cattle are more reactive, and so more likely to react fearfully to unfamiliar stimuli.

Hens

Extreme fearfulness can be such a problem in poultry that the will panic and pile up in a reaction sometimes called 'hen hysteria', smothering some birds in the pile and breaking bones. As with pigs there seem to be links between genes that make hens productive and those that predispose them to showing extreme fear reactions.

However this genetic predisposition is modified by many factors such as the fearfulness of hen even when the eggs are cross-fostered and can only be controlled by keeping these breeds in small groups and carefully controlled environments.

Pigs

Porcine Stress Syndrome is the name of a metabolic disorder common in commercial breeds of pigs used to raised produce lean (aka low fat) pork. This disorder can be traced to a recessive gene. These pigs are particularly susceptible to stress and if frightened may collapse or even spontaneously die.

For example it was shown that mink could be selectively bred to be less afraid of humans, and this boldness also extended to other novel situations. This was considered a good quality to select for in fur-farmed breeding programs as mink are easier to handle if they are calmer.

However just as improving meat quality made pigs more easily stressed, improving temperament (domestication) can easily lead to reduced for quality--as was found in an early Russian study of foxes. Tame foxes are available and Russia to the present day (see right) but they have a pelt more like a dog than a wild fox.

It is not simple to change one gene without having unintended effects on the whole animal.

Temperament, including boldness/timidity is an important part of the suitability of dogs for work (such as police dogs). And genetic play a significant roles in determining a dog's temperament.

Gun-Shy Dogs

Some breeds of dog are specifically used to point or retrieve game during hunting. There appears to be a genetic basis for the occurrence of 'gun shy' dogs who are too fearful to tolerate stresses like the loud retort of a gun shot. (e.g. pointers). Certain lines of dogs are known to produce more gun shy dogs than others.

Pet Dogs

Several domestic breeds are known to have lines that are overly timid, including: the Sheltie. Some research lines of dogs have been specifically bred to be fearful.

Regardless of breeding, early socialization and consistent handling and training can avoid most domesticated animals demonstrating excessive fearfulness during normal day-to-day activities.

A variety of studies have a found a genetic component to fearfulness in diverse animals species including chimpanzees and quail.

Fear and anxiety have been shown to be strongly influenced by genetics in humans and other animals. Several kind of panic disorder have been shown to be transmitted within families as a autosomal dominant trait.