| 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
lateralis 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 contents
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 be
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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