Transcript “Survey of permanent wound tracts in the carcases of culled wild

Culled red deer – lessons from the carcase
Ken Urquhart BVMS, MRCVS
Thistle Veterinary Health Centre, Edinburgh
&
Iain McKendrick, BSc, PhD
Biomathematics and Statistics Scotland,
Edinburgh
Publications
Survey of permanent wound tracts in the carcases of
culled wild red deer in Scotland
Veterinary Record (2003) 152, 497-501
A study to investigate the prevalence of “head
shooting” and the properties of wounds in culled
wild Scottish red deer.
(In Press)
With thanks to Christian Nissen, Highland Game, Dundee
Control of deer populations in GB
• Culling
•Natural mortality
•Accidental death
Cull Data 2001/02
Deer Species
• Red
• Roe
• Sika
• Fallow
• Muntjac & CWD
Scotland
67,300
26,200
3,900
1,200
n/a
England & Wales
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Estimated total GB cull - 175,000 deer (British Deer Society)
Role of Licensed Venison Dealers
87% of cull carcases handled
by LVD’s
LVD = sampling bottleneck ( )
Sample characteristics
 14 sampling days: July-Dec
 1173 carcases (943 + 230)
 50 deer managers ( )
 200 + marksmen
 anonymous
Recommended Points of Aim: BDS
Head
High neck
Low
neck
Chest
Lethal area
25cm diameter
circle
Protection of Deer
• Deer (Scotland) Act 1996
– Close seasons
– Minimum ballistic requirements
Deer cullers are not legally required to demonstrate competence.
Voluntary standards are set by
Peer supervision
Code of practice
Best practice guidance
Formal training : Deer Stalking Certificates
Aims & Objectives
Specifically
• What proportion of deer were head shot and why?
• What proportion of animals were neck shot?
• What proportion of animals were heart/lung shot?
• Number of Permanent Wound Tracts (PWT’s)
Broadly – to establish base line data on current culling practices
Evidence based decision making including
Compliance with Code of Practice and Best Practice Guidance
Content of voluntary training syllabus (Deer Stalking Certificates)
Results
• Head Shooting
• 3.5% elective and 3.9% “coup de grace”
• Neck Shooting
• 12% hinds and 15% in stags
• Body
• 80% of body shot deer were shot through heart/lungs
• Number of wound tracts
• > 1 in 12% - 15% of animals
• Increases significantly during the rut
“analysis using only the anatomical site of entry/exit
wounds will be ….a poor predictor of the outcome
….for culled animals”
Statistical Analysis of Wound Tracts
• Each time a bullet strikes the animal a PWT is created
• The cessation of the wound tract production (bullet
strikes) is likely to coincide with successful culling of the
animal
• “Terminal Probability”* – term describes
– “the mean probability of each successive wound
tract being the final one generated in a carcase”
“a limited but better defined set of data ……an objective measure of the
culling event”
Variations in Terminal Probability
• First PWT , outwith the rut
• First PWT, within the rut
• Subsequent PWT’s
0.88
0.78
0.93
• A lower mean terminal probability is almost certainly
associated with a higher mean time from initial wound to death
• Premature to argue for an explicit correlation between (lower)
terminal probability and animal welfare
– Absence of variables relevant to animal welfare e.g.
• Wound morphology
• Sequence in which wound tracts were created
• Interval between creation of first and last wound tract
Lessons learned
• Elective head shooting is uncommon (3.5%) and indicates
broad compliance with BPG and CoP.
• Neck shooting is common – more research in to
physiological effects of neck shooting is required.
• 20% of body shot deer do not have tracts in heart or lungs
– current concepts of wound analysis in deer are simplistic
compared to human models e.g. Red Cross EXCFVM
• Increased number of wound tracts in stags during the rut
warrants further investigation
Dawn
EXCFVM wound classification
E = entry wound: site & size
X = exit wound: site & size
C = presence or absence of a
cavity
F = fractures, classed on severity
V = vital structure involved
M = presence of one or more
metal fragments in wound
The total amount of energy
deposited in the wound by a
projectile is a major
determinant in the outcome of
war wounds in humans.
This fact has perhaps been
relatively neglected in studies
of culled wild deer and in the
educational literature of
stalkers where the overriding
emphasis remains in
recommending shot placement
which cause maximal damage
to vital (vascular) structures
“In humans, death in < 2 minutes would be considered extremely humane”
Assessing Welfare Standards
• Species specific
• Rabbit
• Fox
• Deer
shot, snared, cage trapped, poisoned (gas)
shot, snared, cage trapped.
shot, enclosure traps
• Method specific
•
•
•
•
Firearms
Snares
Poison
Traps
air weapons, shotguns, rifles
bait, gas
restraining, killing
• Against Agreed Standards
• Catch to kill time
Welfare standards are context dependant