Journal of Morphology 1993 Jul;217(1):105-13.
Electromyographic (EMG) activities of three tail muscles, the extensor caudae lateralis (ECL), abductor caudae externus (ACE), and flexor caudae longus (FCL), were recorded bilaterally in seven adult dogs during walking, trotting, and galloping on a treadmill. Each dog’s movements were recorded with a 16 mm high-speed camera system, and angular movements of the tail were analyzed. During walking and trotting, reciprocal EMG bursts were observed between right and left tail muscles and corresponded with lateral movements of the tail. The tonic discharges that were observed in ECL and FCL seemed to maintain the position of the tail. During galloping, synchronized EMG activity of all tail muscles produced reactive torques to counter those generated by cyclic limb movements and kept the tail in a stable position. These results suggest that tail movements are important in maintaining body balance during locomotion in the dog.
Haworth et al at the Human Biochemical Genetics Unit, University College, London have investigated the genetic basis of a short-tail trait. The investigators have focussed on the T gene, which encodes a T-box transcription factor important for normal posterior mesoderm development.
The investigators have cloned the canine homolog of the T gene and mapped the locus to canine Chromosome (Chr) 1q23. The investigators have analyzed the full sequence analysis of the T gene from a number of different dog breeds identified several polymorphisms and identified a unique missense mutation in a bob-tailed dog and its bob-tailed descendants.
It appears that the offspring from several independent bobtail x bobtail crosses have the homozygous phenotype which is lethal at the embryo stage.
It would be very unlikely that a natural bobtail would develop in a wild canine population for the above reason.
In rats, another animal that has no sweat glands (like the dog), the tail serves a role in thermoregulation, dissipating about 25% of the animals heat. I would say it serves a similar but lesser function in the dog.
Bobcats, Lynx and Mountain Lions make poor comparisons. Bobcats and Lynx hunt small game in cover where a tail
would be an encumbrance. Lynx in North America are almost obligate hunters of the snowshoe hare. Mountain lions are solo hunters of large game more given to chase in partially open spaces. All these animals are sprinters they have more white muscle (fast twitch) than canines. A lynx is not a mountain lion without a tail nor is a mountain lion a lynx with a tail, neither of them is a is a wolf, nor a dog.
Now to the wolf, the forebear of the dog, it has a non-optional, functional tail. Suppose we go to another continent and observe an animal that is not even a canine but occupied the same ecological niche.
Electromyographic and kinematic studies of tail movements in dogs during treadmill locomotion.Wada N, Hori H, Tokuriki M.Department of Veterinary Physiology, Faculty of Agriculture, Yamaguchi University, Japan.
Docking, if a dog has a kinked tail (a trait to be bred away from ) or does work in cover, maybe, considered on an individual basis. Vanity docking every pup of a given breed seems extreme considering the evidence that the tail does have at least a marginal function. This function may never be fully expressed in a kennel or backyard.<