| 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. It has been
reproduced, by kind permission of
the Author.
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
con-ditions 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 association 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.
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 go 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 - Lamarcks 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
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.
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.
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
dogs 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 |
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