French bulldogs are born with naturally short tails. The dog's tail ranges from several inches in length and there may be dogs who do not have tail. The French Bulldog tail should be either straight or kinked (but not curly), short, hung V low, thick root and fine tip; carried low in repose. The screw-tail shape is due to abnormal shape of tail bones, but this abnormality can also affect other parts of the spine with serious consequences.
An understanding of the importance of the tail and the conditions to which a lack of tail can predispose is gained by reviewing the anatomy and the physiology of the normal length tail and the pelvic region. The normal canine tail consists of approximately 20 highly mobile vertebrae largely enclosed by very versatile muscles making the various segments, especially the tip capable of finely graded movements. French Bulldogs have an average of 6 or les vertebraes (often deformed) in their tails which are incapable of fine movement.
Locomotion
The tail is important as a means of counter-balance when the dog is carrying out complicated movements such as leaping, walking along narrow structures, or climbing. Tail muscles are also important in stabilising the vertebral column and supporting the action of the extensor muscles of the back as well as those of the croup and buttocks.
Defecation and pelvic diaphragm integrity
During defecation the dog assumes a squatting position with elevation of the tail an subsequent relaxation of muscles. The movement of the tail during the act of defecation has a direct influence in evacuating the faecal bolus. If the tail is removed from an inmature puppy the muscles of the tail and pelvis may fail to develop to their full potential. Removal of the tail in the mature dog may lead to atrophy and degeneration of these muscles. An absence of adequate function of these muscles may result in rectal dilatation, rectal sacculation and faecal incontinence.
Any process resulting in fascial weakening, muscle atrophy, or muscle degeneration may predispose to this wekness in the pelvic diaphragm. Burrows and Ellison (1989) recorded a predisposition to perineal hernia in those brachycephalic breeds, which have naturally docked tails.
Communication and canine behaviour
The position of the tail and the way it is moved can signal pleasure, fear, friendliness, dominance, playfulness, defensiveness. Thus a very short tail can affect the interaction of dog with other animals and man. Some behaviourists believe the absence of a tail may predispose a dog to show unwarranted aggression to other dogs and man, or that they may be the victim of attacks by other dogs due to their failure to communicate.
The tail is not merely an inconsequential appendage. It is an anatomically and physiologically significant structure which has many biological functions that should not he underestimated.