The answer to whether all dogs have tails is no. The canine tail is an elegant and flexible extension of the vertebral column, composed of smaller bones called caudal vertebrae. While the vast majority of dogs are born with a full tail, exceptions exist due to natural genetic variation and established human practices.
The Biological Purpose of the Canine Tail
The tail serves several dynamic functions, acting as a crucial counterweight for balance and locomotion. During high-speed movements, such as sharp turns, a dog swings its tail to shift its center of gravity, preventing a loss of control. In aquatic environments, the tail functions as a rudder to guide movement while swimming. When a dog walks along a narrow surface, it uses slight tail movements to correct its balance.
Beyond physics, the tail is a highly visible signal used for complex communication. Tail carriage and movement convey a dog’s emotional state, from excitement (a wide, rapid wag) to fear or submission (tucked low or between the legs). Furthermore, the tail’s movement helps fan pheromones from the anal glands, which are chemical signals used to communicate information. A dominant dog holding its tail high spreads its scent widely, while a frightened dog tucks its tail, covering the glands to avoid drawing attention.
Natural Absence: Breeds Born Without Tails
Some dogs are naturally born with a shortened or absent tail, a condition known as a natural bobtail. This is a genetically determined trait caused by a specific mutation, often linked to an autosomal dominant gene variant. The length of the resulting bobtail can vary significantly, ranging from a slight stub to a nearly full-length tail. Breeds known to exhibit this trait include the Pembroke Welsh Corgi, Australian Shepherd, and the Schipperke, among many others.
The inheritance pattern of this gene is dominant but can be lethal when two copies are inherited. Dogs that receive two copies of the bobtail variant (BT/BT genotype) often terminate development in utero, leading to a reduced litter size and sometimes severe spinal defects. Reputable breeders use genetic testing to ensure they do not breed two dogs carrying the natural bobtail gene, thereby preventing the health risks associated with the double-dominant pairing.
Human Intervention: Tail Docking
A significant reason dogs lack tails is the practice of tail docking, which involves the surgical removal or shortening of the tail by human action. This procedure is typically performed on puppies younger than two weeks old, often without anesthesia, by a veterinarian or a breeder. The length of the amputation is determined by the breed standard.
Historically, various reasons supported the practice, including the ancient Roman belief that docking prevented rabies, and later, its use in 17th-century England to classify working animals and avoid taxes. More modern justifications included the belief that docking prevented tail injuries in working dogs moving through dense brush.
Today, the practice is primarily cosmetic, done to conform to traditional breed appearance standards set by kennel clubs. Tail docking is now a subject of considerable ethical debate and is banned or heavily restricted in many countries. Where permitted, exceptions are often made only for working dogs, and the procedure must be performed by a registered veterinarian.