The reliability and forensic soundness of the equine
shin circumference measurement in living animals
versus post-mortem examination
Angelo Peli* and Mariana Roccaro
Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Bologna, Italy
*
Corresponding author at: European College of Animal Welfare and Behavioural Medicine,
Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia (BO), Italy.
Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Bologna, Italy.
Tel.: +39 051 2097594, mob.: 335 8169721, e‑mail: angelo.peli@unibo.it.
Veterinaria Italiana 2018, 54 (4), 281‑286. doi: 10.12834/VetIt.1497.8069.2
Accepted: 22.02.2018 | Available on line: 31.12.2018
Keywords
Forensic science,
Musculoskeletal injury,
Morphometrics,
Racehorse,
Shin circumference,
Welfare.
Summary
Catastrophic injuries in racehorses mostly involve the metacarpal region. Although many
studies describe fractures of equine limbs, few examine the relationship between bone
morphometrics and musculoskeletal problems in racing horses. And yet, according to the
regulation of some Italian traditional races, the shin circumference represents a qualifying
prerequisite for horses to be admitted to races. This study aims to evaluate the conformity of the
shin circumference measurement in living animals and in post‑mortem examinations, in order
to evaluate the forensic reliability of these measurements. The right and left distal forelimbs
from 11 horses of 5 different breeds were examined. The shin circumference was measured
at 3 time points: in the living animal before slaughter/euthanasia, 5 hours post‑mortem, and
after 14‑days of cold storage. The isolated limbs were also weighed in both of the post‑mortem
examinations. In the examined sample, the mean shin circumference was 24.0 ± 2.4 cm in living
animals, 22.9 ± 2.5 cm 5 hours post‑mortem, and 22.4 ± 2.3 cm after 14‑days of cold storage,
with a highly significant difference between these measurements (P < 0.001). There was also a
significant decrease in the limbs’ weight between the 2 post‑mortem examinations (P < 0.001).
According to our findings, the post‑mortem measurement significantly underestimates the
in vivo dimensions of the shin circumference, even when performed a few hours after death;
the forensic soundness of this parameter is therefore limited.
Misurazione della circonferenza dello stinco nei cavalli in vita e nell'esame
post mortem: attendibilità in ambito forense
Parole chiave
Benessere,
Cavallo da corsa,
Circonferenza dello
stinco,
Lesione
muscoloscheletrica,
Scienza forense,
Morfometria.
Riassunto
Nel cavallo sportivo le lesioni interessano con maggiore frequenza la regione del metacarpo.
Numerosi studi si sono occupati delle fratture a carico degli arti del cavallo ma pochi hanno
indagato le possibili relazioni tra l’insorgenza di fratture e la morfometria dei segmenti ossei
interessati. Tuttavia, nei regolamenti di alcune corse tradizionali italiane, come il Palio di Siena,
la misurazione della circonferenza dello stinco rappresenta un requisito imprescindibile
affinché il cavallo possa essere ammesso alla corsa. Scopo dello studio è stato verificare quanto
la misurazione della circonferenza dello stinco eseguita nell’ambito dell’esame post‑mortem
possa differire da quella rilevata sull’animale in vita, per valutare la validità del suo impiego in
ambito forense. A tal fine sono stati esaminati gli arti anteriori di undici cavalli appartenenti
a cinque differenti razze. La circonferenza dello stinco è stata misurata in tre momenti:
nell’animale in vita subito prima della macellazione o dell’eutanasia, cinque ore dopo la morte
e, infine, dopo un periodo di conservazione a ‑20°C per 14 giorni. Gli arti sezionati nel corso
delle due misurazioni post‑mortem sono stati inoltre pesati. La circonferenza media degli
stinchi degli animali in vita è risultata di 24,0 ± 2,4 cm, di 22,9 ± 2,5 cm cinque ore dopo la
morte e di 22,4 ± 2,3 cm dopo conservazione a ‑20°C per 14 giorni. La differenza tra queste
misure si è rivelata statisticamente significativa (P < 0,001). Tra la misurazione effettuata
nell’immediato post‑mortem e quella successiva allo scongelamento è stato inoltre registrato
un significativo calo del peso medio degli arti sezionati, pari al 9,3% (P < 0,001). Secondo
questo studio, la validità della misurazione della circonferenza dello stinco in ambito forense
risulta essere limitata dato che la rilevazione post‑mortem, anche a distanza di poche ore dal
decesso dell’animale, sottostima la circonferenza misurata nell’animale in vita.
281
Forensic soundness of horse shin circumference
Introduction
Catastrophic musculoskeletal injuries (CMIs) of
Thoroughbred racehorses have been reported as
the main reason for wastage (Jeffcott et al. 1982,
Rossdale et al. 1985, Robinson et al. 1988, Lindner
and Dingerkus 1993, Bailey et al. 1997). These
injuries occur either during racing or training and
are not only noxious to the welfare of the horses
(Evans 2002), but can also adversely affect public
perceptions of racing. Minimising and managing
risk factors for this type of injury are therefore
important considerations for those who are
involved in this industry.
In 97% of cases of injury to horses, the limbs are
involved, and in particular the forelimbs, with the
distal part being more susceptible to injuries such as
fractures than other structures (Jeffcott et al. 1982,
Williams et al. 2001, Perkins et al. 2005).
In a study carried out in Canada by Cruz and
colleagues (Cruz et al. 2007) on 76 Thoroughbred
horses with catastrophic musculoskeletal injuries,
the 3 most affected regions were found to be the
metacarpal‑metatarsal region (29%), followed
by carpus (19.7%), and proximal sesamoid
bones (18.4%). In a retrospective cohort study
of Thoroughbred racing in the National Hunt in
Great Britain from 2000 to 2013, more than 75% of
fatalities resulted from catastrophic fracture, with
most involving the third metacarpal (McIII) or third
metatarsal (MtIII) (Allen et al. 2017).
Race injuries in horses are considered to have a
multifactorial aetiology, including genetics and
Peli & Roccaro
age, pre‑existing pathology and past traumas,
biomechanics (conformation), but also race‑related
factors such as race surface and training schedules
(Kobluk et al. 1990, Magnusson and Thafvelin 1990,
Mohammed et al. 1991, Dolvik and Klemetsdal 1996).
There are very few reports on the relationship of
overall body conformation to musculoskeletal
problems in racing Thoroughbred (Anderson et al.
2004). Morphometrical data of equine limb bones
are scant, perhaps because of the difficulty involved
in making consistent and meaningful measurements
of complex shapes, or because of the lack of standard
field‑measurement procedures.
In order to prevent CMIs, some Italian traditional races
like the Palio of Siena have introduced regulations
around the measurement of the ‘shin circumference’.
Measurements are made with a measuring tape in
the thinnest part of the metacarpal region of the
racing horse. In order to be admitted to the race, the
shin circumference must not be below than a given
value. The value is different from race to race, but
usually around 18‑19 cm.
Although there are many reports describing
fractures in the bony elements of equine limbs,
very few of them provide information about
specific morphological details and morphometrical
measures of the affected bones.
Nevertheless, according to current regulations, a
designated veterinarian must measure the shin
circumference of any horse prior to being admitted
to race. If a competing horse sustains a career‑ending
injury or euthanasia and the veterinarian is sued
for malpractice, a second examination of the shin
circumference may be demanded during the legal
proceeding.
The aim of this study is to evaluate the conformity
between the measurement of the shin circumference
in the living animal and in post‑mortem examination
in order to assess its forensic soundness.
Figure 1. Shin circumference measurement in the living horse. The
measurement was performed right above the fetlock joint. Sample 1b.
282
Figure 2. Shin circumference measurement of the isolated limb five
hours after death. Sample 1b.
Veterinaria Italiana 2018, 54 (4), 281‑286. doi: 10.12834/VetIt.1497.8069.2
Peli & Roccaro
Forensic soundness of horse shin circumference
Materials and methods
In this study we examined the right and left distal
forelimbs from 11 horses (10 sent to slaughter and
1 euthanised for tetanus).
The animals were selected randomly and the sample
included 5 breeds: 4 Saddlebreds, 3 Italian Trotters,
2 Thoroughbreds, 1 Haflinger, and 1 Arabian Horse.
The shin circumference of each horse was measured
at 3 time points: In the living animal before slaughter/
euthanasia (T1), 5 hours post‑mortem (T2), and
after 14 days of storage in sealed plastic bags in a
refrigerator set at ‑20°C (T3). Figure 1 shows the shin
circumference measurement of the living animal
taken by placing the measuring tape right above the
fetlock joint.
In post‑mortem examinations, we transected the
distal limbs at the level of the radiocarpal joint
or at the intercarpal joint. Figure 2 illustrates the
measurements taken on the isolated distal limb,
5 hours post‑mortem.
The isolated limbs were also weighed in both of the
post‑mortem examinations. The last post‑mortem
examination was preceded by 24 hours of defrosting.
For some limbs, immersion in water was necessary
to hasten this process.
Statistical analysis was performed using the repeated
measures ANOVA in order to investigate changes in
mean scores over the 3 time points. The Bonferroni
correction was used for post‑hoc analysis. A paired
t‑test was used to compare the limbs’ weight at the
2 post‑mortem time points. A P‑value < 0.05 was
regarded as statistically significant.
Results
Table I lists the subjects included in the study and
their respective shin circumference measurements
and distal limb weights.
In the examined sample, the mean shin circumference
was 24.0 ± 2.4 cm in the living animals, 22.9 ± 2.5 cm
5 hours post‑mortem, and 22.4 ± 2.3 cm after
14 days of storage in the refrigerator. The mean
shin circumference measured 5 hours after death
was therefore 1.1 cm shorter than in the living
animal, whereas the mean circumference after
14 days of refrigeration was 1.6 cm shorter. This
Table I. Shin circumference measurements in the living animal (T1),
5 hours after death (T2) and after 14-days cold storage (T3). Distal limb
weight at T2 and T3.
IT
IT
SB
SB
SB
SB
TH
TH
TH
TH
IT
IT
IT
IT
SB
SB
SB
SB
HA
HA
AR
AR
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Right
Left
Distal limb
weight (kg)
T2
T3
2.0
1.5
2.0
2.0
3.0
2.0
3.0
2.5
3.0
3.0
3.0
3.0
1.5
1.0
1.5
1.5
2.0
2.0
2.0
2.0
2.3
2.0
2.3
2.0
2.0
2.0
2.0
2.0
4.0
3.0
4.0
3.0
2.0
2.0
2.0
2.0
3.0
3.0
3.0
3.0
2.5
2.5
2.5
2.5
The horse breeds are abbreviated as follows: IT = Italian Trotter; SB = Saddlebred;
TH = Thoroughbred; HA = Haflinger; AR = Arabian Horse.
*
the limb was swollen.
Veterinaria Italiana 2018, 54 (4), 281‑286. doi: 10.12834/VetIt.1497.8069.2
Shin circumference (cm)
1a
1b
2a
2b
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b
9a
9b
10a
10b
11a
11b
Shin circumference
(cm)
T1
T2
T3
23.0 23.0 21.5
23.0 21.0 21.0
26.0 25.5 23.0
27.0 24.0 24.0
26.0 25.5 25.0
25.5 25.5 24.5
21.3 19.5 18.5
21.3 20.0 20.0
23.0 21.0 21.0
22.5 21.0 21.0
24.5 24.5 23.5
24.0 23.0 22.5
22.0 21.5 20.5
25.0* 23.5 22.5
29.0 28.0 28.0
29.0 28.0 26.0
23.0 23.0 23.0
23.0 22.5 22.5
24.0 23.0 23.0
24.0 23.0 23.0
20.0 19.5 19.5
21.0 19.0 19.0
30
25
20
15
T1
T2
T3
Figure 3. Box and whiskers plot of the shin circumference
measurements at the three time points.
5
Distal limb weight (kg)
Sample Breed Right/left
id
forelimb
35
4
3
2
1
0
T2
T3
Figure 4. Box and whiskers plot of the distal limbs weight at the two
post-mortem examinations.
283
Forensic soundness of horse shin circumference
reduction corresponds respectively to the 95.4%
and 93.3% of intra‑vitam values, and was found
to be highly significant (P < 0.001). Figure 3 is a
box‑and‑whisker plot illustrating the distribution
of the shin circumference measurements at the
3 different time points. In the living animal (T1) the
median circumference value was 23.5 cm, with a
minimum circumference of 20.0 cm and a maximum
of 29.0 cm. Five hours post‑mortem (T1) the median
circumference was 23.0 cm, with a minimum value
of 19.0 cm and a maximum of 28.0 cm. After 14 days
of refrigeration (T3), the median value decreased to
22.5 cm, with a minimum circumference of 18.5 cm
and a maximum of 28.0 cm.
The limbs’ weight was also found to be significantly
different between the 2 post‑mortem examinations
(P < 0.001). A 9.3% decrease in the mean weight
between T2 (2.48 kg) and T3 (2.23 kg) was observed.
Figure 4 is a box‑and‑whisker plot displaying the
distribution of the distal limb weights 5 hours
post‑mortem and after 14 days of cold storage. At
T2, the median was 2.3 kg, with a minimum value of
1.4 kg and a maximum of 4.0 kg. At T3, the median
was 0.3 kg less, with a minimum value of 1.0 kg and
a maximum of 3.0 kg.
Discussion
Competitive activity in horses involves a unique
challenge in terms of muscular and athletic abilities,
which predispose them to particular types of injury
or disease. Concern about the welfare of horses
involved in the racing industry together with the
popularity of the more well‑known races, such as the
Palio of Siena in Italy, raises an intense public debate.
Regulated examinations should help to ensure that
the welfare of racing horses is not compromised, as
they prevent horses that are unfit from competing.
The shin circumference is considered a formal
requirement for any horse to be admitted to various
traditional races in Italy. Therewith, if a racing horse
sustains a career‑ending injury or euthanasia,
the designated veterinarian’s conduct could be
questioned and a second measurement of the shin
circumference required during the post‑mortem
investigation, most likely on a cold‑stored carcass or
limb after unfreezing.
This study has identified significant morphometric
variations between the shin circumference in
living horses that are then examined post‑mortem,
especially after cold storage time.
This difference can be explained by taking into
consideration post‑mortem phenomena that
normally occur after death, including the arrest of
blood flow and consequent dehydration, the loss
of muscle tone and tissue turgidity, the autolytic
processes, and the decrease in volume of the
284
Peli & Roccaro
underlying synovial bursa. All of these events
critically contribute to the decrease in volume of the
studied structure and thence to the reduction of the
shin circumference.
Moreover, storage conditions of the carcass such
as the temperature and elapsed time prior to
refrigeration, the unfreezing process, the beginning
of putrefactive phenomena, the potential blood
loss that follows sectioning, and the prolonged
compression caused by the riding bandage or
tendon boots left in place even during storage can
contribute to an underestimation of the actual shin
circumference in the living animal.
Given the results of this study, we recommend that
forensic pathologists consider all factors, including
normal post‑mortem phenomena, which are likely
to cause a reduction of the shin circumference.
They should moreover be aware that any measure
acquired during the necropsy is an underestimation
of the actual shin circumference in the living animal.
According to our study, this underestimation is
quantifiable as 4.6% 5 hours after death and 6.7%
after 14‑day storage in a refrigerator set at ‑20°C. The
forensic soundness of this dimensional parameter is
limited.
The correlation between shin circumference and the
incidence of catastrophic musculoskeletal injuries
has not yet been established.
In order to objectively evaluate the relationship
between conformation and the horse soundness,
2 requirements must be met: conformation has to
be quantified in an accurate and repeatable way and
reliable epidemiological data relating to type and
incidence of injury should be available.
However, only a small amount of data concerning the
morphometrics of the McIII is available. A 2006 cohort
study carried out on 108 National Hunt racehorses,
aimed to provide a set of baseline standard
conformational traits within the Thoroughbred
population. The study took into account 98
conformational parameters consisting of segment
lengths, joint angles, inclinations, deviations,
and circumference measurements, including
the mid‑metacarpus circumference. The mean
circumference was 20.15 cm, with a minimum size of
18.00 cm and a maximum of 22.00 cm. Significantly
different circumference measurements were found
between left and right limbs (Weller et al. 2006).
A more recent study aimed at identifying
morphometrical variations of equine metacarpal,
proximal phalangeal, and proximal sesamoid bones
recorded the proximodistal length and mid‑shaft
width and depth of the McIII after boiling, cleaning,
and drying the bone. In Thoroughbred horses, the
mean mid‑shaft widths of the right and left McIII
were respectively 4.09 ± 0.04 cm and 4.02 ± 0.04 cm,
Veterinaria Italiana 2018, 54 (4), 281‑286. doi: 10.12834/VetIt.1497.8069.2
Peli & Roccaro
whereas the mean depths were 3.23 ± 0.07 cm for
the right McIII and 3.26 ± 0.05 cm for the left McIII
(Alrtib et al. 2013). The purpose of Arltib’s study was
to address the lack of information on the normal
range in size and shape of these bones, and to
identify reliable techniques for measuring them that
are not yet applicable in the field.
There is growing interest in equine epidemiology
and the number of retrospective and prospective
studies that try to identify risk factors for certain
injuries has recently proliferated (Cogger et al.
2006, Murray et al. 2006, Verheyen et al. 2006). In
a study investigating the role of conformation
in musculoskeletal problems in the racing
Thoroughbred, Anderson and colleagues (Anderson
et al. 2004), only included the length of the McIII in
the conformation variables, which was found not to
Forensic soundness of horse shin circumference
affect musculoskeletal disease, while conformation
variables associated with metacarpophalangeal
joint problems were long pasterns, offset ratio, carpal
angle, and radio‑metacarpal angle. Contrary to this,
according to Davies and Watson (Davies & Watson
2005), longer McIII bones are associated with ticker
dorsal cortices at the mid‑shaft in racehorses that
were exercising at racing speed, suggesting that the
longer bones do bend more and therefore might be
expected to fracture more easily.
In light of these considerations, further studies are
needed to assess the effects of bone morphology
on fracture incidences. Such data will enable
veterinarians to better estimate the relative
importance of conformational variables, such as
the shin circumference, for future soundness in
racehorses.
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Barbara Ferry