The flowing, visible part of a horse’s tail, often called the skirt or switch, is indeed made of hair, but the entire structure is a complex biological extension of the horse’s body. The long strands are the most recognizable feature, but the tail is firmly rooted in the horse’s anatomy, representing the final segment of the vertebral column. This appendage combines bone, muscle, and specialized hair to serve multiple purposes in the animal’s daily life.
Anatomy of the Tail Dock
The part of the tail that is not hair is known as the dock, which forms the structural base of the appendage. The dock is a highly flexible extension of the spine, composed of a series of small, tapering bones called coccygeal vertebrae. Most horses possess between 18 and 21 of these vertebrae, which decrease in size from the root of the tail to the tip.
These small tail bones are connected by flexible intervertebral discs, allowing for a wide range of motion. Surrounding the vertebrae are several pairs of specialized coccygeal muscles that facilitate movement, allowing the horse to elevate, depress, or clamp the tail down.
A combination of these muscle groups allows the horse to move its tail from side to side in a powerful swishing motion. The entire dock is covered by skin, which is the point where the long, coarse hairs begin to grow. This muscular and bony structure gives the tail its strength and the ability to be actively controlled by the horse.
The Hair of the Horse Tail
The long, flowing hair that grows from the tail dock is often referred to as the skirt or switch, and its composition is primarily the protein keratin. Keratin is a fibrous structural protein that provides the hair with its strength, elasticity, and resilience. This protein forms the bulk of the hair strand, which is protected by an outer cuticle layer.
Tail hair is significantly thicker and more coarse than the short body hair that makes up the horse’s coat. Each strand is anchored in the skin by a hair follicle. The growth cycle of the tail hair is notably longer than that of the coat, which sheds twice a year.
Tail and mane hair can grow at a constant rate, often between 17 and 25 millimeters per month. The active growth phase for these permanent hairs can last for two to three years, leading to the impressive length and thickness seen in a healthy tail. This slow, continuous growth means that proper care, such as careful grooming, is important to prevent breakage and maintain the hair’s protective and aesthetic qualities.
Essential Functions of the Tail
One of the most immediate and visible functions is insect control, where the long hair of the switch acts as a natural fly whisk. The horse uses the strong muscles of the tail dock to swish the tail vigorously, deterring biting insects like flies and mosquitoes.
The tail also serves as an important communication device, conveying information about the horse’s physical and emotional state to other horses and humans. A tail held high may signal excitement or alertness, while a tail tucked tightly against the body often indicates discomfort or anxiety. Subtle movements of the tail transmit messages about the animal’s mood, energy, and mobility.
The tail contributes to the horse’s balance and stability, particularly during quick movements. It acts as a counterbalance, allowing the horse to adjust its weight distribution during dynamic actions like running, turning, or navigating uneven ground. The tail also offers a protective shield, helping to guard the anus and reproductive structures from environmental exposure.