My dog’s hair is on end!

My dog’s hair is on end!

(101 of body language)

Everyone has already seen it on his or her other dog: The fur in the neck area, along the back and / or at the base of the tail is set up. The fur stands on end in the truest sense of the word. It is the so-called pilo erection (“raising the hair”) similar to goose bumps in humans.
One often hears dog owners asking whether the dog deliberately sets the hair up to appear larger or whether the setting up the hair is a clear sign of aggression.

The piloerection, i.e. the raising of the hair / fur, is an involuntarily controllable reaction of the body!

But what does “not deliberately controllable” mean?

Part of the dog’s nervous system consists of the vegetative nervous system, which is divided into the sympathetic and the parasympathetic. The vegetative nervous system is not subject to the conscious control of the organism.
“The sympathetic nervous system controls the mobilization of energy and the activation of bodily functions, which come into play in emergency situations.” ²
By activating the sympathetic nervous system in stressful situations, the heart rate and blood pressure are increased, at the same time the digestive activity and the production of saliva are reduced. Adrenaline from the adrenal medulla is also released into the blood.
They are automatic body reactions on which the organism has no conscious influence. The activation of the sympathetic nervous system triggers escape or defense reactions in stressful situations, i.e. it makes the body ready to act.

Why is there now a pilo erection?

The hair follicles are connected to the hair bar muscles (the so-called “Musculus arrector pili) along the skin. These muscles are stimulated by the sympathetic nervous system and are therefore not consciously controlled. By releasing the adrenaline in stressful situations (see last paragraph), these muscles contract. By contracting the hair-bar muscles, the associated hair follicles and the hair are set up accordingly: Piloerection occurs
Now, at the latest, I think it is clear that the dog cannot consciously control the setting up of the hair, since it is controlled by an area of ​​the nervous system (the vegetative nervous system) that is responsible for the control of involuntary processes. It is similar with human goose bumps. The occurrence of goose bumps in humans is also controlled by the sympathetic nervous system of the vegetative nervous system and therefore cannot be caused by humans at will. Have you ever tried? ?

In what situations does dog piloerection occur?

Contrary to popular belief, piloerection is not a clear sign of aggression. Piloerection can be based on various moods that put the dog in stress, e.g.

  • fear
  • Excitement
  • Surprise
  • uncertainty
  • excitement / tension
  • nervousness

Not much data has been collected on dog piloerection, ethologist Dr. However, from her years of experience with many different dogs, Karen B. London has observed that there are mainly three different patterns of piloerection, each of which is associated with a different behavior, probably based on the dog’s different, underlying emotional state: ³
Pattern 1: Thin line from hair set up along the back to the base of the tail; Dr. London associates a high level of self-confidence and from their experience, the dog will be more likely to go on the offensive and show aggressive behavior.
Pattern 2: Wide spots (up to 20 cm wide) of fur on the shoulders, which runs a maximum of 10 cm along the back. Dr. London associates this pattern with dogs that are less self-confident and can often be a little fearful.
Pattern 3: Piloerection along the shoulders and around the base of the tail, but not along the back. This pattern often occurs in dogs that are in an ambivalent emotional state and are in conflict. (Ambivalent = contradictory). These dogs are often incalculable in their behavior.

Because of the hair that is set up, a dog looks bigger and can be more threatening to others, but this is not deliberately controllable by the dog.

The erection of the hair (piloerection) is controlled by the part of the nervous system that is responsible for involuntary processes in the body. Different states of mind of the dog can trigger the piloerection.

The type of piloerection depends not only on the underlying emotion, but also on the race and the nature of the coat. Furthermore, a piloerection is not a clear sign of aggression, but is also triggered in dogs that are nervous, insecure or very aroused.

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