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It has been recognised for many years that castration and tail docking
of lambs causes pain and distress.
Behavioural and physiological
measurements have been used to quantify the amount of pain associated with
different methods and at different ages. All methods of quantifying pain
have their limitations. For example there is a maximum cortisol
concentration rise in response to stimulation and greater stimulation
cannot cause a higher cortisol peak. In behavioural measurements there may
be problems deciding which of two abnormal behaviours, such as abnormal
activities or alternatively standing abnormally still, indicated worse
pain.
- "All of the
methods of castration and tail docking of lambs, whether surgical or by
ring or by Burdizzo clamp, carried out on unanaesthetised lambs, cause
acute pain." (J15.14.w3)
- "Available evidence suggests that all methods of castration and
tailing cause pain and distress which may be detected by alterations in
behaviour such as posture and activity, and by alterations in cortisol
concentrations in the blood." (D153)
- Behavioural changes due to the acute pain produced by surgical
castration and tail docking are different from those seen following
application of rubber rings: activity is reduced and postures are adopted
which appear to be designed to reduce/avoid mechanical stimulation of
inflamed and hyperalgesic tissues. (J15.14.w3)
Recent work has shown that not only is acute pain experienced in the
first hours after castration, but that behavioural signs of pain are
present in the three days following castration with rubber rings in lambs
of one week or four to six weeks of age. (J147.11.w1)
Noxious stimuli from the scrotum may be more important than noxious
stimuli from the testes in development of the acute cortisol response to
castration by rubber ring or Burdizzo clamp, as indicated by a reduction
in cortisol responses following full-width application of a clamp in
combination with rubber rings, but not when ring application is combined
with the clamp applied to the two spermatic cords individually, leaving
intact scrotal tissue medially, and also as indicated by the marginal
reduction in cortisol response to short scrotum versus ring castration,
and the marginal reduction when local anaesthetic is injected into the
spermatic cords prior to ring application, compared with the significant
reduction when local anaesthetic has been injected into the scrotal neck
or both testes (if this is due to leakage of local anaesthetic into the
vaginal cavity). (J10.45.w3)
Scientific studies on pain associated
with lamb castration and tail docking:
There are qualitative differences in the responses of individual
lambs to a particular method of castration, although the qualitative
responses are generally similar for a given method of castration and
tailing. (J15.14.w3)
- Recording of behaviour, using a dynamic and interactive visual
analogue scale (DIVAS), and of mechanical nociceptive thresholds in
lambs following castration of lambs (four to six days old) by surgery,
rubber ring, or combined surgery and ring, found that behavioural
(DIVAS) results indicated that surgical castration was the most
painful method, then rubber ring castration, while the combined
Burdizzo clamp application (across the whole scrotum) with the rubber ring reduced pain-related
behaviours compared to the ring alone. Measuring the mechanical
nociceptive threshold indicated that surgery produced a prolonged
period of hypoalgesia (increased nociceptive threshold), suggesting
response of the endogenous antinociceptive system, the rubber ring
produced a period of hypoalgesia followed by hyperalgesia (increased
then decreased nociceptive threshold) and the combined rubber ring
plus Burdizzo produced a similar response to rubber rings but with a
more pronounced hypoalgesic phase, suggesting a greater response of
the endogenous nociceptive system. It was suggested that this
indicates a greater initial stimulus of pain/distress when the
combined method is applied than if rubber rings are applied alone and
"questions the validity on welfare grounds of using a greater
initial stimulus to reduce subsequent short term pain."
[1997](J290.24.w1)
- A study comparing lambs castrated and tail docked at five, 21 or 42
days old, by rubber ring application, surgical castration (including
cautery of the tail stump) or ring in combination with application of
a Burdizzo clamp, found behaviour indicating considerable pain in all
groups of lambs in the first three hours after castration and tail
docking. Lambs castrated and tail docked with rubber rings showed the
most changes of behaviour, with significantly higher restlessness and
abnormal lying and standing postures than those seen in other groups.
Lambs in which a Burdizzo clamp was applied across the scrotum and
tail for six seconds each after the relevant rings had been applied
showed significantly reduced levels of abnormal behaviour compared to
those in which the rings alone were applied. Surgical castration,
which included for the tail application of a Burdizzo clamp prior to
cutting and cautery immediately afterwards, followed by release of the
clamp, appeared to cause less behavioural changes than ring
application but more than ring plus Burdizzo. It was noted that more
"statue standing" was seen in the labs following the
surgical procedure and it was suggested that this behaviour minimises
stimulation of sensitized tissues and may reduce pain suffered. There
appeared to be few differences in the responses associated with the
age of the lambs, although the surgical method appeared to be more
painful in the five-day-old lambs than in the older groups. [1993](J21.55.w1)
- A study comparing lambs castrated and tail docked at five, 21 or 42
days old, by rubber ring application, surgical castration (including
cautery of the tail stump) or ring in combination with application of
a Burdizzo clamp, found that compared to rubber ring alone the plasma
cortisol concentration peak occurred earlier and was 28 nmol/lL lower;
values returned to pre-treatment levels within 84 minutes compared
with 96 to 138 minutes for lambs in which only the rubber rings were
applied. Within the group receiving the Burdizzo-plus-ring treatment,
some individuals showed a high cortisol response, similar to that seen
in those receiving the rubber rings alone, while other had a lower
cortisol response, similar to that seen in control handled lambs; this
may be due to variation in the efficacy of application of the Burdizzo
clamp. Surgical castration produced a cortisol peak earlier than that
seen with application of rubber rings and levels had not returned to
pre-treatment values within 180 minutes of the procedure. The faster
rise to peak cortisol levels seen with the surgical procedure and the
application of the Burdizzo clamp were considered to be due to
immediate substantial tissue injury with these two methods while the
rubber rings produce, via developing ischaemia, a slower build up of
tissue damage and nociceptor activity. Lambs castrated and docked with
rubber rings at 42 days old were noted to show a significant increase
in abnormal behaviours and higher plasma cortisol responses between
138 and 180 minutes, while five-day-old lambs receiving the combined
rubber ring and Burdizzo clamp procedure also showed a significant
increase in abnormal behaviours and higher plasma cortisol responses
between 138 and 180 minutes. Five-day-old lambs showed a significantly
higher and earlier cortisol peak than older (21- or 42-day-old) lambs,
which may be due the output of the adrenals being greater per litre of
blood plasma in these smaller animals. [1993](J21.55.w2)
- A study of behavioural signs and cortisol responses following
castration and/or tail docking found that lambs of up to seven days
old showed "mild distress" following tail docking and
"marked distress" following castration and docking. Behavioural indicators of distress [pain] in lambs were considered to
include restlessness - frequent standing up and lying down, rolling,
kicking and stamping - lateral recumbency, immobility with neck
extension, and hyperventilation. [1989](J21.46.w2)
- Following tail docking with rubber rings of lambs of up to seven
days old, in the first 15 to 30 minutes lambs stood up and lay
down frequently and lay in an abnormal lateral position for about
one third of lying observations; they also kicked, stamped, tail wagged
and occasionally bleated; after about 30 minutes these behaviours
became less prevalent and by 60 minutes most were lying ventrally,
asleep. Plasma cortisol concentrations were slightly higher than
those seen in control handled lambs and peaked at 30 minutes. (J21.46.w2)
- When lambs of up to seven days old were both castrated and tail docked
with rubber rings, in the first 15 minutes they stood and lay down
again frequently, lay in lateral recumbency, commonly kicked,
rolled briefly onto their backs and occasionally bleated. While
lying laterally the neck was often extended and the dorsal lip
curled up. Activities then declined so by thirty minutes most were
lying (40% laterally, 45% ventrally), moving very little, neck
extended, eyes closed, and hyperventilating (frequent deep
breaths), until about 60 minutes after the procedure; after this
time these behavioural signs diminished and most were lying
ventrally, asleep, by 90 minutes. Plasma cortisol concentrations
rose markedly, peaking at more than 40 ng/mL at 30 minutes but
declining to control values (approximately 10 ng/mL) by 90
minutes.(J21.46.w2)
- Following castration with rubber rings at one day old (first day
after birth), during the first fifteen minutes lambs stood up and lay
down frequently, and commonly lay in lateral recumbency with three or
all four legs extended; kicking was also common, while several lambs
rolled briefly onto their backs. The necks of the lambs were usually
extended whether the lamb was lying laterally or ventrally, and the
upper lip was often curled. Occasionally lambs bleated. Activity then
decreased progressively so that by 30 minutes after ring application
most were lying down, 75% laterally and 22% ventrally, with the neck
extended, eyes closed and respiration deep and frequent
(hyperventilating). At about 60 minutes these behaviours rapidly
disappeared and may 90 minutes most animals were lying ventrally and
asleep. Castrated lambs showed significantly greater integrated
cortisol responses than did control handled lambs (P<0.01); the
integrated cortisol responses of castrated lambs was not significantly
different from the response seen to ACTH stimulation (P<0.08).
[1991](J21.51.w1)
- Goat kids castrated with rubber rings on the day after birth
showed mainly standing in the first 30 minutes, with few postural
changes or bleating and lateral recumbency seen only 3 to 9% of the
time. After this, to 60 minutes, they mainly lay, with 33% of kids
in lateral recumbency and 33% in ventral recumbency, with the neck
extended, but with less obvious hyperventilation than was seen in
lambs; 34% stood still during this time. By 90 minutes most were
lying ventrally, asleep. The integrated cortisol response of
castrated goat kids was significantly higher (P<0.01) than that
of control handled kids but significantly lower (P<0.001) than
that of ACTH stimulated kids. (J21.51.w1)
- A study of lambs of about 65 days old, castrated and tail docked
using rubber rings, found that while plasma ACTH and cortisol levels
had returned to control levels by 2.5 to 3.0 hours after the procedure
was carried out, blood pressure (systolic, diastolic, mean arterial)
and heart rate were still elevated at four hours after application
of the rings. It was suggested that heart rate and blood pressure
measurements may be more sensitive indices of low grade pain than are
plasma ACTH and cortisol concentrations, although an alternative
explanation was that by four hours there is still a small shift in
sympathetic tone in the absence of low-grade pain. It was noted that
the time at which ACTH and cortisol concentrations peaked varied
widely between lambs, from 20 to 100 minutes after application of the
rubber rings, suggesting wide variation in the time to maximum pain-induced distress. (J10.50.w1)
- A study compared the effects of different types of bloodless
castrators on the behavioural and cortisol responses of four- to
six-day-old lambs to castration with rubber rings plus Burdizzo
(bloodless castrator clamp). There were no significant differences in
the cortisol or behavioural responses depending on the type of
bloodless castrator used (225mm 'baby' Burdizzo, Ritchey (Little)
Nipper or a hydraulically powered instrument), but the hydraulically
powered instrument produced the lowest cortisol response (not
statistically significant) and it was considered by the operator to
cause the least pain on application. Application of the bloodless
castrator proximal rather than distal to the ring had a slightly
greater effect in pain reduction but it was noted that care must be
taken that application is distal to the teats, in order to ensure that
the urethra is not crushed. (J35.162.w1)
- A study compared the effects of different tail docking methods
on the behavioural and cortisol responses of four- to six-day-old
lambs to castration with rubber rings plus Burdizzo (bloodless
castrator clamp). Use of a hot docking iron resulted in the least
evidence of acute pain, while use of the Burdizzo in combination with
the rubber ring resulted in less evidence of acute pain than use of
the rubber ring alone. (J35.162.w1)
- Lambs docked with the hot iron had a significant increase in
plasma cortisol levels compared with control handles lambs and did
show significantly more time in some abnormal postures and also
trembling, but trembling occurred in only the first six minutes
while active behaviours and time spent in normal lying postures
were not significantly altered. Use of the combined ring plus
Burdizzo tail docking method resulted in a significantly higher
(p<0.05) restlessness score than following use of the hot
docking iron, but lower increases than those seen when rubber ring
tail docking was used. Use of the ring alone for docking produced
a significantly higher score for limb and tail activity as well as
significantly higher peak cortisol and area under the cortisol
curve and the area under the cortisol curve was not significantly
different from that seen with rubber rings alone used for both
castration and docking. With use of a rubber ring alone for both
castration and tail docking peak cortisol response, incidence of
active behaviours, and time spent in abnormal postures were all
significantly higher than with any of the tail docking methods
together with the combined (rubber ring plus Burdizzo) castration.
(J35.162.w1)
- A study compared acute cortisol responses of lambs of about 50 days
old when castrated and tail docked using rubber rings alone, ring
alone for tail docking and ring plus clamp, applied distal to the ring
to each spermatic cord but not to the central scrotal tissue, for
castation, and ring
plus clamp for both scrotum and tail, again with the median portion of
the scrotum not crushed by the clamp. The study did not show any
difference in cortisol secretion depending on whether or not the clamp
was used. [1997](J24.75.w2)
- All three groups showed significant cortisol responses
(P<0.001) following the procedures, peaking at 30
(ring-and-clamp castration, ring tail docking) or 45 minutes
(other groups). There were no significant differences in plasma
cortisol responses between the groups of lambs other than that at
30 minutes the mean cortisol concentration of lambs in the group
with ring-and-clamp castration, ring tail docking was
significantly higher than that for the ring castration, ring tail
docking at the same time. (J24.75.w2)
- It was noted that this result was different from that seen in
other experiments in which the clamp was applied across the whole
scrotum and it was considered probable that that the area of
uncrushed scrotal tissue provided undamaged nerve fibres in this
region allowed nociceptive impulses from ischaemic scrotal tissue
to be transmitted cranially. Other possible factors in the difference
of results were the type of castrator used (Ritchey
Nipper rather than Burdizzo) and the breed of lambs. (J24.75.w2)
- A study compared the integrated cortisol responses (area under the
cortisol-time concentration curve for four hours after the procedure)
of lambs to castration and tailing using combinations of surgery,
rubber rings and (for tail docking) a heated docking iron in lambs of
four to five weeks old. The study concluded, based on the integrated
cortisol response as a measure of acute distress, that surgical
castration and/or tailing resulted in the greatest acute distress in
the lambs, that tail docking with a ring caused less stress than ring
castration alone or ring castration plus tailing (the later two
causing similar levels of distress to one another), that tail docking
with a docking iron or with a ring caused similar levels of distress,
but with a shorter acute distress response with the docking iron than
with rubber rings and that castration plus tail docking both with
rubber rings, short-scrotum plus tail docking with rubber rings and rubber
ring castration plus docking iron tailing produced similar
levels of distress to one another. All lambs showed a transient
increase in plasma cortisol level. In lambs castrated surgically
(bottom third of the scrotum cut off with a sharp knife, testes drawn
out using serrated tongs) and/or tail docked with a sharp knife,
cortisol had not returned to pre-treatment levels by four hours after
the procedure, whereas in other groups it had. It was noted that the
lower response to tail docking with the heated docking iron may be
related to destruction of nociceptors. [1991](J10.39.w2)
- A study looked at the cortisol responses of lambs of about 40 days
old to surgical castration and/or tail docking, and also tested
whether handling for blood sampling affected the cortisol response.
The study showed that cortisol responses were completed in
approximately eight hours in all the lambs. Lambs of all groups showed
a protracted cortisol response with levels returning to pre-treatment
levels at 450 and 420 minutes in two groups (handled and blood samples
every 15 minutes or not handled until 90 minutes, then every fifteen
minutes respectively) and levels approaching but still significantly
different from pre-treatment levels at 480 minutes in two other groups
(handled from 240 minutes or only at 480 minutes). [1991](J10.39.w3)
- A study looked at cortisol responses of lambs to tail docking by
rubber ring, castration by rubber ring, and administration of ACTH
from four hours after birth to seven days old in two breeds of sheep
(Dorset and Scottish Blackface). In both breeds the integrated
cortisol response was dependant on treatment (P<0.001), with least
responses in control lambs, then (in order of increasing response) in
tail docked, castrated and docked, and ACTH-injected lambs. In
Scottish Blackface lambs there were no significant changes with age in
response to control handling, tail docking or castration whereas in
the Dorset lambs responses increased between four hours and one day
old then decreased. In both breeds there was a significant (P<0.05
in Dorset, P<0.01 in Scottish Blackface) decrease in cortisol
response to injection of ACTH between four hours and seven days of
age. By expressing the cortisol response to
noxious stimuli as a percentage of the response to a fixed dose of
ACTH it was shown that in both breeds there were "marked
increases in their apparent ACTH secretory responses to noxious
stimuli during the first one to three days after birth",
however it was further noted that "it would be premature to
conclude that the distress caused by noxious stimulus increases during
the first one to three days after birth." [1989](J21.46.w3)
- A study compared the behavioural and cortisol responses of lambs of
five- to six-days-old to castration and tail docking by standard
rubber rings, smaller rubber rings, a combination of rings plus
Burdizzo with the Burdizzo applied across the whole scrotum or
tail just distal to the ring for ten seconds at each site, or
Burdizzo alone, applied conventionally to each side of the scrotum
across the spermatic cord for ten seconds each side, and across the
whole width of the tail for three seconds. The study found that while
all methods of castration and tail docking caused considerable acute
pain, based on combined behavioural and cortisol measurements, the
combined "ring plus Burdizzo" method produced least pain and
the small rubber rings produce more intense pain than the standard
rubber rings but lasting for a shorter period. [1995](J3.136.w3)
- With the Burdizzo alone the main behavioural responses included
decreased activity and abnormal postures, including statue
standing and "dog-sitting", but few active behaviours
such as foot stamping; the cortisol response peaked at a level at
least twice of that seen in control handles lambs and was still
raised at 180 minutes. With the combined method time spent in
abnormal postures was not significantly different from that seen
in Burdizzo-treated lambs but the time spent standing abnormally
was less and no dog-sitting was seen, less time was spent lying in
abnormal positions than in either of the rubber-ring groups,
levels of active behaviours were similar to those seen in the
control and Burdizzo groups and more time was spent in normal
postures than in the other castrated groups; the increase in
cortisol was smaller and of shorter duration than after any of the
other castration methods and reduced to pretreatment levels by 48
minutes. With both rubber rings there were markedly more active
behaviours and tail wagging, these being seen mainly in the first
42 minutes in the lambs castrated with the small rings and in the
first 72 minutes with the standard rings, time spent in abnormal
postures was greater than in control lambs and for standard rings
was significantly higher than that seen with the Burdizzo or
combined treatment. Lateral lying predominated with the small
rings and included rolling, kicking etc., particularly in the
first 12 minutes, while with the standard rings abnormal ventral
lying, also sometimes with rolling and kicking, was predominant in
the first 30 minutes. Active abnormal standing was seen rather
than statue standing. The cortisol peak was higher and earlier
with the smaller rings than with the standard rings but the
difference was not statistically significant. [1995](J3.136.w3)
- A study compared the acute cortisol response and wound healing in
three- to six-week-old lambs castrated and tail docked by rings or by
combined rings plus application of a Burdizzo castration clamp to the
whole width of the scrotum just distal to the ring, for either six or
ten seconds. Only a marginal reduction in cortisol response was seen
with the combined method compared to rings alone but healing of the
scrotal wounds were faster with the combined method. It was noted that
flinching was observed in every lamb when the clamp was applied to the
scrotum or tail and that this "would be a significant
impediment to farmers adopting widely the ring plus clamp method."
[2000](J24.78.w1)
- Ring castration and docking produced a marked rise in plasma
cortisol, significant (P<0.05) by 200 minutes, peaking at 60
minutes and returning to pre-treatment values by 170 minutes.
Responses in the combined treatment groups were broadly similar,
but the response peaked at 40 minutes in the lamps with 6 second
clamp application and showed a plateau at 60 to 110 minutes in the
lambs with 10 second clamp application. The only between-group
significant difference was a lower cortisol level
(P<0.05) at 60 minutes in the lambs receiving the 10 second
clamp and there were no significant differences in the integrated
cortisol responses between groups. There was a trend for faster
healing of the scrotal wounds in the lambs treated by the combined
method, for example at four weeks after treatment, 8% versus 3%
had progressed to a small star-shaped scar. [2000](J24.78.w1)
- A study compared the behavioural and cortisol responses of lambs to
castration and tailing by knife, rubber rings (castration or short
scrotum), or (tailing only) heated docking iron. The study found that
on the basis of the combined cortisol and behavioural responses,
surgical castration and tail docking caused greater and more
protracted pain than the other methods and should be avoided, but that
ring castration or ring castration plus docking also caused distress
and that "more benign alternatives" should be looked
for. [1996](J10.44.w3)
- With all methods the plasma cortisol level increased, then
decreased to control values within 2.5 to 3.5 hours of the
procedure, except in lambs castrated and/or docked with the knife.
Following castration and/or tail docking with a knife, restless
behaviours were not a feature but abnormal standing/walking,
particularly "statue standing" was a major behaviour and
this continued up to and beyond the end of the period of
observation (four hours). With the rings, high levels of
restlessness were seen in the first 30 to 45 minutes, most
standing/walking was abnormal and lying was mainly abnormal and in
short bouts, but all behaviours returned to control values within
the four hours. Behavioural responses in lambs tail docked with a
heated docking iron were generally similar in type to those in
lambs docked with a knife, but lasted for a shorter time, reducing
to normal values within the four hours, and the integrated
cortisol response was at least 2.8 times less than in the lambs
tail docked with a knife. It was noted that it was not possible to
tell whether "restlessness" type behaviours or
"abnormal standing/walking" indicated a greater amount
of pain. [1996](J10.44.w3)
- A study comparing the behavioural responses of lambs of three ages,
(five, 21 and 42 days) to different castration methods (rubber ring,
combined Burdizzo clamp and rubber ring, surgical) found that
all methods at all ages "produced changes in behaviour which
could be interpreted as evidence for the presence of considerable pain
during the first three hours after treatment." [1993](J21.55.w1)
- A study used visual analogue scale (VAS) scoring for active
behaviours, unresponsive behaviour and scrotal pain (on palpation) in association with cortisol measurements and mechanical
threshold testing for quantification of pain responses associated with
three different castration methods in mixed breed lambs of four to six
days old. Active pain behaviours, which were virtually absent from
control lambs, were seen in castrated lambs for up to three hours
after castration; the highest scores were for ring castration,
followed by the combined method, with the lowest scores for surgical
castration. Looking at unresponsive behaviours, the pattern seen in
ring or combined method castrates was similar to that of active pain
behviours, while surgically castrated lambs showed higher levels of
this behaviour than did control lambs for the whole eight hour
observation period following castration. Looking at scrotal pain, in
surgically castrated lambs this rose steadily to a peak by six hours
then fell to pre-castration levels by 72 hours, while in those
castrated by the other two methods, the initial rise was similar in
pattern to that seen for active pain behaviours, but did not return to
pre-castration levels in the 72-hour observation period. Integrated
pain responses were significantly higher than those seen in control
lams whichever castration method was used; the greatest integrated
active pain behaviour was seen with ring castration and the least with
the combined method. All castration methods caused rises in plasma
cortisol and the rises were significant in ring and surgically
castrated lambs at 15 minutes and in the rubber ring castrates at one
hour, compared with controls; at eight hours no group had
significantly higher cortisol, but at 24 hours a significantly higher
level was seen in those castrated by the combined method, compared to
all the other groups. Surgery or the combined castration resulted in a
significant rise in the threshold response to a mechanical noxious
stimulus compared to control lambs, while those castrated with rubber
rings showed a slight rise then a slight fall in threshold. [1999](J21.66.w1)
- A study of behavioural responses of lambs of two ages (one-week-old
and four- to six-weeks-old) to rubber ring or combined rubber ring and
Burdizzo (whole width of scrotum, 10 seconds) castration, found that
in the three days following castration some behaviours which are
considered normal in lambs were reduced, such as gambolling in
one-week-old lambs (P=-.033) and lying in four- to six-week-old lambs
(P= 0.0002). Postures
considered abnormal, although sometimes seen prior to castration, were
seen significantly more frequently (P=0.0025) in four- to six-week-old lambs
following castration. Use of the combined method produced some
reduction in these effects on behaviour, although the differences were
not statistically significant. (J147.11.w1)
- Lambs of eight weeks old castrated and tail docked by rubber rings
showed a rise in mean plasma cortisol level to 50 minutes after ring
application, which then declined slowly, remaining significantly
higher than in control handled lambs from 20-180 minutes, to return to
levels seen before the rings were applied by 210 minutes. Plasma
noradrenaline concentrations increased markedly to 10 minutes after
the rings were applied, remained at a high level until 30 minutes then
returned to original levels by 60 minutes; mean concentrations were
higher than in controls from 10 to 40 minutes. The rise in
noradrenaline occurred during the onset of ischaemic pain. No rise in
plasma adrenaline concentration was recorded; it was suggested this
may be due to a lack of detection: the first blood sample was taken
five minutes after ring placement and plasma catecholamines have a
half-life of only one to two minutes, therefore the study may not have
detected any immediate and short lived adrenaline response to
placement of the rings. (J24.80.w2)
Rubber rings:
- Application of rubber rings for tail docking and castration is
simple, cheap and effective. However in lambs of all ages it produced
considerable pain for more than an hour, as can be shown by hormonal (cortisol)
and behavioural measurements. (J35.162.w1)
- Several studies have shown that application of rubber rings "can
cause pain sufficient to dominate the experience of the lamb for more
than one hour." (J15.14.w3)
- Following application of rubber rings to the scrotal neck of lambs
for castration, vigorous afferent activity was recorded including
activity from formerly silent units with receptive fields in the
pampiniform plexus in particular. There was a rapid adaptation of the
multi-unit discharge within 10 seconds followed by a discharge pattern
decaying exponentially over 90 minutes and showing two components with
inflections at approximately 90s and 16 min. Afferent activity
initiated by application of rubber rings was shown to persist for
periods in excess of 90 minutes; this time course is similar to that
shown for behavioural and humeral changes in response to the same
procedure. Neither standard nor smaller diameter rubber rings were
effective in rapidly blocking slowly conducting afferent fibres in
the superior spermatic nerve by neuronal pressure block.
Intratesticular injection of local anaesthetic was shown to rapidly
block afferent fibres running in the superior spermatic cord. (J287.19.w1)
- A study using behavioural and cortisol responses to castration and
tail docking of young lambs (five to six days old) with tight rubber
rings indicate that the procedure caused "intense pain and
distress for at least one hour." [1991](J21.51.w3)
- Rubber ring castration and tail docking of five- to six-day-old
lambs caused a significant rise in plasma cortisol level, peaking
at approximately 30 minutes after the procedure, significantly
raised (p<0.05) to at least 60 minutes and returning to
pretreatment levels after 90 minutes. [1991](J21.51.w3)
- Five- to six-day-old lambs castrated and tail docked by rubber
rings showed significantly higher levels (p<0.05, compared to
control handled lambs) of lateral recumbency (in the first hour)
and of standing and walking (in the first 30 minutes and in the
120 to 180 minute period). Ventral lying was significantly lower than
controls in the first 60 minutes and was higher in the 120-180
minute period. [1991](J21.51.w3)
- In lambs of three weeks old, cortisol responses were similar after
Burdizzo clamp, a powered castration clamp or rubber ring combined
with a Burdizzo clamp applied across the whole scrotum for ten
seconds; the cortisol response was most prolonged after use of the
powered castrator. Behavioural responses with the three methods were
similar to one another with significant increases (compared to control
handled lambs) in time spent in abnormal postures (P <
0.01), particularly statue standing with the Burdizzo or powered clamp
and abnormal lying for the combined ring and Burdizzo method,
significantly greater amounts of time spent trembling (P <0.05),
mainly in the first 60 minutes after castration, and significantly
greater time showing active behaviours (restlessness, easing quarters
and total active behaviours). [1997](J35.153.w1)
- Rubber ring castration caused significantly more (P <
0.01) combined active pain related behaviours, abnormal ventral lying,
lateral lying and total abnormal lying and total abnormal postures,
less normal ventral lying than in control lambs, and also significant plasma cortisol
responses, peaking at about 60 minutes after castration and returning
to control values at about 120 minutes. [1998](J35.155.w1)
- Rubber ring castration and tail docking caused consistent active
behaviours indicative of discomfort (e.g. restlessness, easing the quarters, tail wagging not associated with sucking, rolling,
vocalisation not associated with suckling, turning the head to an
abnormal position, generally to look at/lick the scrotum) in neonatal
lambs, with scores being significantly (P<0.01) greater than those
for control handled lambs, and with castration plus tail docking of
male lambs producing a significantly (P<0.01) greater effect than
tail docking alone in ewe lambs. (J3.149.w3)
Rubber ring plus Burdizzo:
- Several studies have indicated that combining use of rubber rings
with crushing the innervation to the testes, scrotum and tail using a
clamp (Burdizzo) reduces the duration of pain, compared to use of
rubber rings alone, although the immediate pain at the time of
application is increased. (J3.136.w3,
J21.55.w1, J35.162.w1,
J35.155.w1, J290.24.w1)
Evidence from use of local anaesthesia:
"Behaviour elicited by treatment can be validated as measures
of noxious sensory input if effective local anaesthesia returns levels
close to those seen in control animals." (J10.47.w3)
- Administration of local anaesthesia prior to rubber ring castration
and tail docking in lambs eliminates the behavioural signs and the
plasma cortisol changes which are normally seen following castration
and tail docking, indicating that the behavioural and cortisol
responses are due to pain. [1991](J21.51.w3)
- Both the testes and the scrotum contribute noxious sensory input
following ring castration but the cortisol response to ring
application can be abolished by injection of local anaesthetic into
the neck of the scrotum or into both testes before application of the
rings. Injection into the spermatic cords reduced the cortisol
response but this reduction was not significant. [1997](J10.45.w3)
- Pre-treatment with local anaesthetic reduced levels of active pain
behaviours, unresponsive behaviours and scrotal pain on palpation
measured by VAS following ring or combined ring and Burdizzo clamp
(full scrotal width) castration to levels similar to those seen in
control lambs. [1999](J21.66.w1)
Evidence from administration of naloxone:
- A study indicated that endogenous opioids do reduce pain in young
lambs following castration and tail docking but have only a slight
effect. Administration of intravenous naloxone (opiate antagonist)
prior to rubber ring castration and tail docking in lambs resulted in
the treated lambs reaching a higher plasma cortisol concentration,
from a lower starting level, than seen in lambs subjected to
castration and tail docking alone, although this difference was not
significant. There was an increase in lateral (abnormal) lying
behaviour in the naloxone treated lambs in the first hour after
castration; this was significant (P<0.05) only in the 30 to sixty
minute period. Some lambs showed increased teat seeking and sucking,
which may be an additional mechanism for alleviation of acute pain and
distress. [1991](J21.51.w3)
Evidence for chronic pain:
- When tails from docked and undocked lambs were examined post
mortem, obvious swelling was visible in the distal nerve stump of
three of six docked lambs but not in any undocked lambs. Histological
examination revealed terminal neuromata at the distal ends of the main
coccygeal nerve trunks in two docked tails and complex neuromata
(multiple, discrete irregularly distributed nerve bundles within
connective and scar tissue) in two other docked tails. It was
suggested that the presence of the neuromata suggested the possibility
of chronic pain or increased sensitivity remaining "long after
amputation." [1992](J21.52.w1)
- Lambs castrated by rubber ring at two days old showed behaviours
such as licking directed towards the affected area, and movements of
the hind limbs and tail, "which may be considered as evidence
of chronic pain". The incidence of such behaviours was
greater in lambs castrated at 42 days, and lesions which developed
were also more severe in the older lambs. [2000] (J35.160.w1)
- A study on lambs castrated and tail docked by rubber ring alone,
or with local anaesthesia or combined with Burdizzo clamp (across
the whole scrotum) at less than two days old, found that an
inflamed lesion developed at the site of the rubber ring on all
lambs with no significant effect of method on maximum lesions
score, although the combined method did cause the lesion to develop
and to heal more quickly. All tails but one had dropped off by 28
days. The time taken for the scrotum to drop off was not
significantly affected by method (although only 20% had dropped
off by 28 days in the ring group compared to 50% in the other
groups) nor was the maximum lesion width or maximum lesion score;
the time to maximum lesion width was lower for the lambs castrated
with the combined method. Pus developed at the scrotal site in 35%
of lambs and at the tail in 40% of those given local anaesthetic
or the combined method but not in any lambs in which the rubber
ring was used alone. Behaviourally (comparing ring castrated, ring
castrated with local anaesthetic, and control handled lambs), in
lambs castrated by rubber rings there were significantly higher
incidences of the active behaviours foot stamping, kicking and
tail wagging and combined (foot stamping, kicking, easing quarters,
scratching quarters and tail wagging) than in control handled
lambs or those given local anaesthetic, and there was a
significantly higher incidence (compared to control handled lambs)
of head turning to and licking of the inside hind leg and scrotum
and although this behaviour generally correlated only poorly with
lesion severity it was seen at highest incidence at the same time
as the most severe lesion score, for the two lambs showing the
highest incidence of this behaviour. Playing on a box was reduced
by half in ring castrated lambs compared to handled controls and
those given local anaesthetic, and gamboling was also lower, but
the differences were not significant. Ring castrated lambs also
showed higher incidences of abnormal lying postures, abnormal
standing and lying idling, and fewer normal standing and play
postures than handled lambs or those given local anaesthetic prior
to ring application. There were no effects of treatment on
liveweight gain. [2000] (J35.160.w1)
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