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    Cosmetic Tail Docking of Dogs’ Tails. ROBERT K WANSBROUGH Picasso Crescent, Old Toongabbie, New South Wales 2146 This article was published in the Australian Veterinary Journal Vol 74, No. 1, July 1996. SUMMARY : The anatomy of the canine tail and its relationship to the physiological functions of the tail are described and the effect of tail docking on these is discussed. Current knowledge on the physiology and anatomy of pain is described with particular reference to cosmetic tail docking in the neonatal puppy. Recent advances in knowledge about pain and the changes in approach to pain management refute the premise that 'Puppies do not feel pain therefore tail docking is not Inhumane', and also the premise that 'the pain and the effects of tail docking are insignificant.' Six criteria to tell the 'necessity' to dock dogs are presented. The article shows that the reasons advanced for tail docking do not satisfy these criteria and so that docking dogs' tails cannot be justified. Tail docking is an old custom, which is entrenched in certain dog breeds. This article aims to provide scientific information relevant to the cosmetic tail docking of dogs There have been no scientific studies or double blind trials conducted to compare the effects of tail docking in one sample of dogs with a similar sample of undocked dogs. Similarly there have been no studies that measure the initial pain and the ongoing pathological pain inflicted on docked dogs. Due to the phenomena of deafferentation (suppression of afferent nerve impulses) and phantom limb pain, scientific regulatory bodies would not permit such inhumane research. Even without this information from specific scientific research, our current knowledge is sufficient to show the canine tail is an anatomically and physiologically important organ which should not be docked simply because tradition dictates it. Cosmetic tail docking cannot be justified medically or scientifically and recent advances in our knowledge about pain indicate that it should he regarded as an inhumane act. CRITERIA TO TEST THE 'NECESSITY TO REMOVE OR MODIFY ANY PART OF A DOG. The following questions have been proposed by Morton (1992) to test the necessity to modify or remove any part of a dog. 1. Is there evidence that leaving the dog intact predisposes them to harmful consequences? 2. Is there evidence that the interference is in the best interests of the dog and will be beneficial to the dog? 3. Would the harmful consequences or the benefit occur in a significant proportion of dogs and therefore justify the procedure on all dogs of a particular breed? 4. Does the proposed interference cause greatest harm to the dog than the damage one is trying to prevent? 5. Is there another way with no, or lesser adverse effects that would achieve the same end? 6. Does the increase in 'value' as a result of the interference justify the harm done to the dog? ANATOMICAL CONSIDERATIONS. An understanding of the importance of the tail and the conditions to which docking can predispose is gained by reviewing the anatomy and the physiology of the tail and the pelvic region. The canine tail usually consists of 20 (6 to 23) highly mobile vertebrae largely enclosed by a very versatile musculature making the various segments, especially the tip capable of finely graded movements. Part of the musculature is formed from muscles associated with the rectum, the anus, and the pelvic diaphragm. The tail is served by 4 to 7, paired coccygeal nerves. On leaving the spinal canal the branches of these nerves anastomose to form the left and right dorsal and ventral coccygeal trunks which lie on their respective surfaces of the transverse processes of the vertebrae. The dorsal muscles of the tail are direct continuations of the epiaxial musculature of the trunk. The dorsal sacrococcygeal muscles are extensors, while the sacrococcygeus ventralis later- alis and medialis muscles act as flexors or depressors of the tail. These muscles have many tendons that insert from the 5th or 6th coccygeal vertebra then onto the next vertebra and so on to the end of the tail. The coccygeus, levator ani, and the inter-transversarius caudac muscles are lateral flexors of the tail. The rectococcygeus muscle is composed of external fibres from each side of the rectum with the left and right portions fusing at the level of the 3rd coccygeal vertebra then inserting on the 5th and 6th coccygeal vertebrae. This attachment on the tail serves to support, anchor and stabilise the anal canal and the rectum, preventing them from being pulled cranially by a peristaltic wave. By its contraction, the rectococcygeus muscle can move the anal canal and rectum caudally thus evacuating faecal material (Miller 1969). The pelvic diaphragm is the vertical closure of the pelvic cavity formed by the coccygeal muscles. The coccygeal muscle originates on the ischiatic spine, extends to the lateral surface of the tail and inserts on the 2nd to 5th coccygeal vertebrae. The levator ani muscle (m coccygeus medialis) originates on the ilium, pubis and pelvic symphysis, radiates upwards surrounding the genitalia and the rectum and ends on the 4th to 7th coccygeal vertebrae. Besides helping to contain the con-tents of the pelvic cavity the levator ani muscle moves the tail cranially and laterally, presses the tail against the anus and the external genitalia, compresses the rectum and causes the sharp angulation between the 6th arid 7th coccygeal vertebrae which is characteristic for defecation. Only in carnivores does the levator muscle reach the vertebrae of the tail, thus the detri-mental effect of tail docking on the role of this muscle will be more significant in the dog compared with other domestic species. PHYSIOLOGICAL ASPECTS. 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. DEFÆCATION. Normally the rectum, anus, and anal canal are devoid of faecal material with the walls in apposition. During defecation the dog assumes a squatting position with elevation of the tail and subsequent relaxation of the coccygeus, the levator ani, and the rectococcygeus muscles. This allows the migrating contractions in the colon to push the faeces distally into the rectum with defecation ensuing. The movement of the tail during the act of defecation has a direct influence in evacuating the rectum and anal canal of the last part of the faecal bolus. The coccygeus and levator ani muscles cross the rectum laterally tending to compress the tube, while the recto- coccygeus shortens the tube. After defecation the muscles return to their normal position with oncomitant obliteration of the empty lumen. If the tail is removed from an immature 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, in addition, if these muscles lose their distal attachments there may be a lessening of the support and anchorage of the rectum and anus. An absence of adequate function of these muscles may result in rectal dilatation, rectal sacculation and faecal incontinence. PELVIC DIAPHRAGM INTEGRITY. Perineal hernia involves a breaching of the caudal wall of the pelvic cavity with herniation of the rectum, the abdominal contents or the pelvic contents through an opening bordered by the anal sphincter medially, the coccygeal muscle laterally and the internal obturator ventrolaterally. Any process resultmg in fascial weakening, muscle atrophy, or muscle degeneration may predispose to this weakness in the pelvic diaphragm. Often perineal hernias occur secondary to medical conditions which cause tenesmus with resultant weakening of the pelvic diaphragm. Burrows and Ellison (1989) recorded a predisposition to perineal hernia in those brachycephalic breeds, which traditionally have their tails docked, and suggested that inherent conformational deficiencies may contribute to the disease in these breeds. Canfield (1986) compared long-tailed and docked Corgis and found that the levator ani and the coccygeus muscles did not develop fully in the docked dogs. A relationship with perineal hernia potentially exists, but she considered that further research was required before a categorical statement could be made. ACQUIRED URINARY INCONTINENCE. Urinary incontinence in bitches caused by urethral sphincter mechanism ncompetence (SMI), is a multi factorial condition. A recent study (Holt and Thrusfield 1993) noted the increased risk of SMI developing in large breeds but it also concluded that bitches belonging to small breeds had a reduced risk and medium breeds had no increased risk. Breeds identified in this study as having significantly increased risk of developing SMI were the Old English sheepdog, Rottweiler, Doberman Pinscher, Weimaraner and Irish Setter. A reduced risk was demonstrated in the Labrador retriever, and, although the result was not statistically significant, a low risk was observed in the German shepherd. This agreed with the observations of Arnold et al (1989).Holt and Thrusfield (1993) noted 2 consistent associations between SMI and tail docking which they interpreted as an indication that docked breeds of whatever size are more likely to develop incontinence than undocked dogs of the same breed. It is well recognised in women that the risk of developing genuine stress incontinence (GSI) is related to pelvic floor muscle damage during labour. In the bitch the equivalent 'pelvic floor' muscles are the levator ani and coccygeus muscles both of which attach to the tail base, and it is possible that these muscles are atrophied and/or damaged in docked breeds reducing urethral resistance. A similar relationship may exist between tail docking and submissive urinary incontinence in puppies. Holt and Thrusfield (1993) conclude that their results provide some evidence to support the arguments against tail docking and that it would be interesting to determine if the predisposition to urinary incontinence in currently docked breeds such as the old English Sheepdog and Doberman Pinscher would be reduced if they cease to be docked. COMMUNICATION AND CANINE BEHAVIOUR. The position of the tail and the way it is moved can signal pleasure, fear, friendliness, dominance, playfulness, defensiveness, inquisitiveness, aggression, nervousness and submissiveness. Thus tail docking can affect the interaction of dogs 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 (RJ Holmes personal communication) Dogs are playing an increasingly significant role as pets and companion animals. Their role in the reduction of emotion and stress related diseases in western society is well recognised, as is their important role in companion animal therapy with children, the handicapped and the elderly. Therefore, good, clear communication with 'man's best friend' is of paramount importance and anything that may impair this communication should he avoided. Tail docking is one such thing. PAIN Recent advances in our knowledge of pain physiology and anatomy are relevant to the discussion of cosmetic tail docking. Pain is a feeling, a complex summation of nociceptive input, emotion and state of arousal. Physiological pain is normal, has a short duration and can be protective, but pathological pain is abnormal, is often persistent and can be debilitating and counterproductive. Pathological pain is the sensation perceived from the inflammation that accompanies tissue injury or the sensation perceived from damage directly to the nervous system. Clinically, pathological pain is characterised by one or more of the following: • The presence of sponataneous pain - pain that occurs in the absence of a demonstrable stimulus. • Widening of the painful area - 'flare reaction.' • Hyperalgesia - where (the response to a painful stimulus is exaggerated) • Allodynia - where a normally innocuous stimulus is painful. • Referred pain - where the pain from injured tissues spreads to intact tissues. • Sympathetic dystrophy - a pathological interaction between the sensory and the sympathetic nervous systems. Unlike physiological pain, pathological pain has no thresh-hold. The nervous system is a plastic, modifiable system with a propensity for adaptation and maladaptation and peripheral and central sensitisation are the mechanisms underlying the generation of pathological pain (Dart 1994). PERIPHERAL SENSITISATION. Nociceptors (pain receptors) are activated directly by mechanical and thermal stimuli and also by endogenous substances released from inflamed, traumatised and ischaemic tissues. Serotonin, products of the arachidonic cascade, histamine, kinins and acetylcholine are all algogenic (directly pain producing). Prostaglandins and nor-adrenalin may not be directly painful, but sensitise the nociceptors and potentiate the effect of other algogenic substances. Substance P is secreted from the excited or sensitised nociceptors and induces vasodilation, increased vascular permeability, mast cell degranularion and production of unstored inflammatory substances. The formation of this 'sensitising soup' leads to sensitisation of adjacent nociceptors and so the vicious cycle of 'peripheral sensitisation' is set in motion. Sensitised nociceptors can become spontaneously active causing depolarisation of 'dorsal' horn neurons, and thus peripheral sensitisation is one of the phenomena involved in the development of pathological pain. CENTRAL SENSITISATION. At the spinal cord level, the balance between the afferent stimuli reaching the dorsal horn and the degree of activity of inhibitory interneurons will determine the strength and frequency of the stimuli registering in the brain. A cascade of intracellular events is initiated and as a result identical but repeated stimuli can evoke a larger and larger response because the potentials are summated. The dorsal horn neurons become hyperexcitable this reaction is termed 'dorsal horn wind up'. The hyperexcitability of the dorsal horn neurons increases the activity in preganglionic sympathetic neurons and as a result postganglionic sympathetic efferents release noradrenalin which sensitises primary afferent terminals. These in turn initiate central sensitisation, which further increases sympathetic outflow and this increases afferent input. So another vicious cycle is set in motion. Pathological pain can he seen to he the result of peripheral and central sensitisation. INCORRECT MYTHS ABOUT PAIN. Several myths about pain have been propagated for years and form the basis on which cosmetic tail docking has been justified and allowed to he perpetuated. MYTH 1 - Animals don't feel pain like humans. This is illogical. Anatomically and physiologically mammals (and possibly all vertebrates) have the same neural transmitters, receptors, pathways and higher brain centres. Whilst it is true that animals may show different signs of pain, we cannot deny that they feel pain in the same way humans do (Fleeman 1995). Because of the physiological similarity between mammals, it is valid to use animals, including dogs, as models for human medical research. The converse applies in that man can be used as a model for advancing veterinary knowledge. Similarity between the human and canine nervous systems means that we can assume that anything causing pain in man will cause a painful sensation of similar intensity in the dog. The pain threshold has been determined to be approximately equal in humans and animals (Fleeman 1995). MYTH 2 - Lack of myelination is an index of immaturity in the neonatal nervous system and therefore neonates are not capable of pain perception. We know this is no longer correct, in fact the contrary occurs. Anatomical studies have shown that the density of cutaneous nociceptive nerve endings in the late foetus and newborn animal may equal or exceed that of adult skin (Anand and Cart 1989). Nociceptive impulses are conducted via unmyelinated and thinly myelinated fibres. The slower conduction velocity in neonatal nerves resulting from incomplete myelination is offset by the shorter interneuronal and neuromuscular distances that the impulse has to travel. It has been shown, using quantitative neuroanatomical methods, that nerve tracts associated with nociception in the spinal cord and brain stem are completely myelinated up to the thalamus during gestation (Anand and Cart 1989). Further development of the pain pathways occurs during puppyhood when there is a high degree of 'brain plasticity.’ The development of descending inhibitory pain pathways in the dorsal horn of the spinal cord and the sensory brain stem nuclei also occurs during this period, therefore painful and other experiences during this period may determine the final architecture of the adult pain system. THE PAIN OF TAIL DOCKING. Tail docking involves the removal of all or part of the tail using cutting or crushing instruments. Muscles, tendons, 4 to 7 pairs of nerves and sometimes bone or cartilage are severed. The initial pain from the direct injury to the nervous system would be intense and at a level that would not be permitted to be inflicted on humans. The subsequent tissue injury and inflammation, especially if the tail is left to heal as an open wound will produce the algogenic substances, the 'sensitising soup' and the 'dorsal horn wind up' required for peripheral and central sensitisation and the development of ongoing pathological pain. Puppies are usually subjected to this pain and trauma at 2 to 5 days of age when the level of pain would he much greater than an adult would experience because the afferent stimuli reaching the dorsal horn from a greater density of sensitised cutaneous nociceptors will exceed that of the adult and the strength and frequency of painful stimuli reaching the brain will he greater because inhibitory pain pathways will not be developed. • The whimpering and the 'escape response' (continual movements) exhibited by most puppies following tail docking, are evidence that they are feeling substantial pain. Animals tend to be more stoic than humans due to an inherent preservation instinct. • Because some puppies do not show signs of intense suffering, it does not mean that the pain inflicted on them has not registered in their central nervous system. Cosmetic tail docking is most often performed without any anaesthesia or analgesia and only manual restraint is used. General anaesthesia, if used, produces unconsciousness and muscle relaxation but does not affect the sensory nerves and will not necessarily prevent 'dorsal horn wind' up or the development of pathological pain. Movement of the patient may be controlled, but sensory stimuli will still register in the higher centres of the central nervous system. On recovery from anaesthesia peripheral and central sensitisation, the mechanisms underlying the generation of pathological pain will still he present. General anaesthesia in very young animals entails a high degree of risk Local anaesthesia, because of the practical difficulties of injecting into such a small area and the potential for systemic toxicosis, also has a high risk. The maximum dose of lignocaine in the dog is 5 mg/kg making use of the 2% (20 mg/ml.) solution urealistic in the average puppy up to a week of age. Use of local anaesthetics to which adrenalin has been added could increase the risk of cardiovascular and CNS problems occurring, although some proponents of tail docking recommend the use of these solutions to prolong analgesia and to help control haemorrhage (RA Zammit in a submission prepared for the New South Wales Canine Council). Understanding the phenomena of peripheral and central sensitisation and their role in the generation of pathological pain, has changed the approach to pain management. The emphasis is now on preventing pain and treating pain before it occurs. About 90% of human amputees suffer pathological pain in the form of phantom limb pain. Docked dogs similarly may suffer phantom limb pain but, if their inherent stoicism masks the symptoms, this may he misdiagnosed or goes undiagnosed. The currently recommended anaesthetic procedure for a human undergoing surgery where major peripheral nerves are to he severed, would involve epidural anaesthesia for 48 h before surgery and 24 h after surgery. local anaesthesia around the surgical site at the time of surgery and for 24 h after surgery. OTHER POTENTIAL SEQUELAE FROM TAIL DOCKING. Other sequelae that may result from tail docking are:- • Haemorrhage or ischaemia. • Infection, gangrene, toxaemia/septicaemia. • Meningitis. • Hypoglycaemia or hyperglycaemia. • Amputation neuroma formation. • Caudal adhesions with neurodermatitis. • Deafferentation, causing loss of sensory perception from the tail. Many of these can potentially produce a state of shock which may prove fatal to the neonatal puppy. SOME REASONS FOR TAIL DOCKING PRIOR TO THE 19TH CENTURY • To produce bobtail puppies - Lamarck’s theory of acquired characteristics was still widely believed and people thought the new born puppies would look like their parents. • To prevent rabies - it was thought that docked dogs were less likely to develop rabies. • To avoid tax - docked dogs did not attract tax. • To strengthen the back and increase speed. • To prevent being bitten when ratting or fighting. • To make better 'sport' of bear baiting and dog fighting. These reasons from which the custom of tail docking evolved are no longer valid. (Note - Have they ever been valid?) REASONS GIVEN TO JUSTIFY TAIL DOCKING TODAY • Prevention of injury in hunting and working dogs. Most dogs in the breeds that are generally docked are kept as pets and companion animals and are never used for hunting or working. The most popular breeds used in the field or paddock are Labradors, Kelpies, Border Collies and Cattle dogs, none of which are required to have their tails docked. • Prevention of injury in short coated dogs especially those with exuberant and ebullient temperaments. This is inconsistent because not all breeds in this category are required to be docked, for example the Dalmatian and the Labrador. The boxer is often cited a dog requiring docking for this reason, but some professional dog trainers note a difference in the behaviour of this and other traditionally docked breeds when they are left undocked and 'urge and encourage all breeders to forget about what has happened in the past and now change to keep their dogs' tails on" (Tucker 1994). A survey in Edinburgh by Darke et al (1985) over a 7 year period showed that there was insufficient evidence of statistical significance, to suggest that there is a positive association between tail injuries and an undocked tail and that tail docking could not be recommended as a measure to prevent tail injuries in any dog population similar to the predominantly urban population surveyed. Of the first 1000 consultations at the North West Animal Emergency Clinic in Sydney none involved tail injury cases. Between December 1991 and September 1992 there were 2350 consultations only 3 of which involved tail injuries. All three of these cases were related to tail docking, the first case involved 12 three day old Rottweiler pups which were still haemorrhaging 6 hours after being docked and required suturing. The other two cases involved single pups one of which was bleeding and the other had become infected (From records of the North West Animal Emergency Centre, Baulkharn Hills, NSW.) Not all tail injuries require amputation, so tail docking may be routinely performed on 100% of puppies of certain breeds as a measure to prevent injuries that would only require a bandage, some antiseptic or simply natural healing. • Hygiene Dogs such as the Old English sheepdog, poodle and silky terrier would foul themselves and the average pet owner would not have the time, patience or skill to carry out proper coat care. This is inconsistent because other breeds with the same potential problem (for example the Bearded collie, Pekingese, Maltese terrier and Afghan) are not required to be docked. Regular clipping of long-haired areas and 'feathers' is far less invasive and painful than tail docking and has far fewer adverse effects. Poor breed selection, lack of education in dog husbandry or irresponsible pet ownership should not be justification for tail docking. TRADITION OR CUSTOM Submitting dogs to a procedure known to be painful and which may have harmful consequences, just to satisfy a centuries old custom, cannot he justified in a humane society. CONCLUSION Cosmetic tail docking cannot be justified on scientific or medical grounds. Unless pecuniary or traditional reasons are to take priority over the welfare of the animal, then the criteria to justify removal of a dog’s tail are not satisfied. The tail is not merely an inconsequential appendage. It is an anatomically and physiologically sign significant structure which has many biological functions that should not he underestimated. Tail docking can predispose the dog to detrimental consequences including intense, initial pain and continuing pain related, neurological problems. Tail amputation should only be performed on those dogs whose tail or associated structures have been injured or where there is occult pathology of this appendage. If tail amputation is indicated as a therapeutic measure, appropriate anaesthetic and surgical techniques should be employed. The neonate is anatomically and physiologically able to and in fact does feel pain. Therefore veterinarians who wish to be seen as caring professionals and as the guardians of animal welfare must stop cosmetic tail docking and actively oppose anyone else continuing the painful practice. REFERENCES Anand KJS and Carr DB (1989) Paediatric Clinics Of North Am. 36:795 Arnold S, Arnold P. Hubler M, Casal M and Rusch P (1989) Schwelzer Archiv fur Tierheilkunde 131: 259. (English translation European J. of Companion Anim Practice (1992) 2:65) Burrows C and Elilson G (1989) In Textbook of Veterinary Internal Medicine, 3rd edn, edited by Ettinger SW, Saunders Philadelphia.p1559. Canfield R (1986) Anatomical Aspects of Perineal Hernia in the Dog, PhD Doctoral thesis, University of Sydney Darke PGG, Thrusfield MVand Aitken CGG (1985) Vet Rec 116:409 Dart CM (1994) In Pain and its Control University of Sydney Post Graduate Commitee In Veterinary Science, Proceedings No 226. p333. Fleeman L (1995) Control of Pain - What's the Latest? University of Melboume Veterinary Clinic and Hospital. Holt PE and Thruslield MV (1993) Vet rec 133:177 Miller M (1969) Anatomy of the Dog, Saunders, Philadelphia. p 189 Morton D(1992) Vet Rec 131:301 Tucker M (1994) AVA News Oct p 16