https://doi.org/10.52973/rcfcv-e34321
Received: 18/09/2023 Accepted: 13/10/2023 Published: 22/01/2024
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Revista Científica, FCV-LUZ / Vol. XXXIV, rcfcv-e34321
ABSTRACT
Distal extremity lesions are prevalent in racehorses and cause mild–
to–severe lameness, adversely affecting the racing life of horses.
This study aimed to determine the incidence of distal extremity
lesions in racehorses, to clinically and radiologically assess those
lesions. The study included 158 limbs from 140 horses with distal
extremity lesions among 282 horses of different breeds, age and
sex that were presented to Equine Hospital of the Directorate of
Diyarbakir, Turkey, Hippodrome with various clinical complaints
during a racing season. Following anamnesis, the horses were
clinically examined and lameness was localised. In cases where the
lameness could not be localised upon physical examination, regional
anaesthesia was performed, followed by radiological assessments
based on radiographs acquired from different positions. Clinical and
radiological examination revealed that 84.17% of the cases occurred
in the forelimb and 15.82% in the rear limb, and the lesions in the
forelimb were mostly located in the carpal joint (26.58%), metacarpus
(25.31%) and metacarpophalangeal joint (23.41%), whereas those in
the rear limb were located in the tarsal joint (7.5%). Therefore, the
lesions in the forelimbs were more prevalent than those in the rear
limbs of the affected racehorses. Radiography remains a satisfactory
imaging technique for the diagnostic imaging of distal limb injuries
in horses owing to its cost–effectiveness.
Key words: Distal extremity; radiological examination; racehorse
RESUMEN
Las lesiones distales de las extremidades son frecuentes en los
caballos de carreras y causan cojera de leve a grave, lo que afecta
negativamente la vida de los caballos en las carreras. Este estudio
tuvo como objetivo determinar la incidencia de lesiones de las
extremidades distales en caballos de carreras, evaluar clínica y
radiológicamente esas lesiones. El estudio incluyó 158 miembros
de 140 caballos con lesiones en las extremidades distales entre
282 caballos de diferentes razas, edades y sexos que fueron
presentados al Hospital Equino de la Dirección del Hipódromo de
Diyarbakir, Turquía, con diversos problemas clínicos durante una
temporada de carreras. Después de la anamnesis, los caballos fueron
examinados clínicamente y se localizó la cojera. En los casos en los
que la cojera no pudo localizarse mediante el examen físico, se realizó
anestesia regional, seguida de evaluaciones radiológicas basadas
en radiografías adquiridas desde diferentes posiciones. El examen
clínico y radiológico reveló que el 84,17 % de los casos ocurrieron
en el miembro anterior y el 15,82 % en el miembro posterior, y las
lesiones en el miembro anterior se localizaron mayoritariamente en
la articulación del carpo (26,58 %), metacarpo (25,31 %) y articulación
metacarpofalángica (23,41 %), mientras que los del miembro posterior
se localizaron en la articulación del tarso (7,5 %). Por lo tanto, las
lesiones en las extremidades anteriores fueron más prevalentes que
las de las extremidades traseras de los caballos de carreras afectados.
La radiografía sigue siendo una técnica de imagen satisfactoria para
el diagnóstico por imagen de lesiones de las extremidades distales
en caballos debido a su rentabilidad.
Palabras clave: Extremidad distal; examen radiológico; caballo de
carreras
Clinical and Radiological Evaluation of Distal Extremity Lesions in
Racehorses
Evaluación clínica y radiológica de lesiones de las extremidades distales en caballos de carreras
Berna Ersöz–Kanay
1
, Emine Çatalkaya
1
* , Neval Berrin Arserim
2
, Muzaffer Aydın Ketani
3
, Berjan Demirtaş
4
1
Dicle University, Faculty of Veterinary Medicine, Department of Surgery. Diyarbakir, Türkiye.
2
Dicle University, Faculty of Veterinary Medicine, Department of Microbiology. Diyarbakir, Türkiye.
3
Dicle University, Faculty of Veterinary Medicine, Department of Histology and Embryology. Diyarbakir, Türkiye.
4
Istanbul University –Cerrahpasa, Vocational School of Veterinary Medicine, Equine and Equine Training Programme. İstanbul, Türkiye.
*Corresponding Author: eminecatalkaya21@gmail.com
Evaluation of Distal Extremity in Racehorses / Ersöz-Kanay et al. ___________________________________________________________________
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INTRODUCTION
Distal limb lesions are prevalent in racehorses and cause varying
degrees of lameness. Lameness is one of the most important
causes of poor performance and is associated with substantial
economic losses in horses (Equus caballus). Accurate diagnosis
is the rst step of effective treatment [1]. Clinical examination is
crucial in determining the cause of lameness. However, sometimes
it proves to be insucient and thus imaging techniques are required.
Radiography is a preferred imaging technique for lameness and limb
examination in horses owing to its low cost and the ability to evaluate
solid structures, including bones [2]. Radiological examination is a
frequently used auxiliary examination method to try to diagnose the
cause of lameness, including osteophytic growth or enthesophytes
(dorsal metacarpal disease (DMD), osselet, exostosis of metacarpus,
form (ringbone), bone spavin among others), osteoarthritis, fractures
and dislocations, intraarticular fragment fractures, cartilage and soft
tissue calcications, foot penetration and foreign body penetration [3].
This study aimed to examine the incidence of distal extremity
lesions in racehorses with intensive and exhaustive exercises, to
clinically and radiologically assess those lesions.
MATERIALS AND METHODS
The study included 158 limbs from 140 horses with distal extremity
lesions among 282 horses of different breeds, age and sex that
were presented to Equine Hospital of the Directorate of Diyarbakir
Hippodrome, Turkey with various clinical complaints during a racing
season (2022 race year).
Clinical examination (inspection, direct and indirect palpation, trot
examination, examination on a lunge) was performed upon taking
detailed anamnesis from the individuals in charge of the horses included
in the study. Cases of lameness upon clinical examination were scored
according to the American Association Equine Practitioners (AAEP)
lameness scoring system [4]. Regional anaesthesia (intraarticular,
palmar digital nerve blockade, abaxial nerve blockade and lower four–
point nerve blockade) was performed in cases where lameness was
determined on clinical examination but it could not be accurately
localised. Regional anaesthesia was performed from distal to proximal
extremity. In those cases, the region was localised upon decreased or
complete recovery of lameness. Standard radiographic views of the
specic affected anatomic area were obtained (TABLE I). Detomidine HCl
(Domosedan, Zoetis, Turkey) at a dose of 20–40 µg·kg
-1
was administered
intravenously to uncooperative horses, with rough temperament during
the X–ray (Gierth, HF 80, Japan) procedure. Data from the horses’ clinical
and radiological examinations were recorded. Each radiographic image
was separately examined, and the lesions were classied based on
region and percentage rate evaluated thereafter.
RESULTS AND DISCUSSION
Based on the records, 282 thoroughbred Arabian and British
racehorses underwent X–ray imaging for various reasons in a racing
season at the Equine Hospital of the Directorate of Diyarbakir
Hippodrome. The X–ray procedures were performed for acquisition
TABLE I
Radiographic positions used for radiographic examination
Front Limb
Carpus
Dorsopalmar (DPa)
Lateromedial (LM)
Dorsolateral–palmaromedial 45° oblique (D45L–PaMO)
Dorsomedial–palmarolateral 30° oblique (D30M–PaLO)
Flexed lateromedial (Flexed LM)
Flexed dorsoproximal–dorsodistal 30° oblique (exed D30Pr–DDiO)
Flexed dorsoproximal–dorsodistal 80° oblique (exed D80Pr–DDiO)
Metacarpus
Lateromedial (LM)
Dorsopalmar (DPa)
Dorsolateral–palmaromedial oblique 55 ° (D55L–PaMO)
Dorsomedial–palmarolateral oblique 55 ° (D55M–PaLO)
Metacarpophalangeal
joint (Fetlock)
Lateromedial (LM)
Dorsopalmar
Dorsoproximal–palmarodistal 30° oblique (D30Pr–PaDi)
Flexed lateromedial (exed LM)
Dorsoproximal–dorsodistal 45–70° oblique (D45–70Pr–DDiO)
Lateroproximodorsal–mediodistopalmar 20° oblique (L20Pr20D–MDiPaO)
Dorsolateral–palmaromedial 45° oblique (D45L–PaMO)
Dorsomedial–palmarolateral 45° oblique (D45M–PaLO)
Hoof
Dorsopalmar (DPA)
Lateromedial (LM)
Dorsoproximal–palmarodistal 30° oblique (D30Pr–PaDiO)
Palmarodistal oblique (PaDiO)
Dorsoproximal–palmarodistal 60° oblique (D60Pr–PaDiO)
Palmaroproximal–palmarodistal 45° oblique (Pa45Pr–PaDiO)
Hind Limb
Tarsus (Hock)
Lateromedial (LM)
Dorsoplantar (DPl)
Dorsomedial–plantarolateral 55° oblique (D55M–PlLO)
Dorsolateral–plantaromedial 35° oblique (D35L–PlMO)
Metatarsus
Lateromedial (LM)
Dorsoplantar (DPl)
Dorsolateral–plantaromedial oblique 55 ° (D55L–PlMO)
Dorsomedial–plantarolateral oblique 55 ° (D55M–PlLO)
Metatarsophalangeal
joint (Fetlock)
Lateromedial (LM)
Dorsoproximal–plantarodistal 30° oblique (D30Pr–PlDi)
Flexed lateromedial (exed LM)
Dorsoproximal–dorsodistal 45–70° oblique (D45–70Pr–DDiO)
Lateroproximodorsal–mediodistoplantar 20° oblique (L20Pr20D–MDiPlO)
Dorsolateral–plantaromedial 45° oblique (D45L–PlMO)
Dorsomedial–plantarolateral 45° oblique (D45M–PlLO)
Hoof
Dorsoplantar (DPl)
Lateromedial (LM)
Dorsoproximal–plantarodistal 30° oblique (D30Pr–PlDiO)
Plantarodistal oblique (PlDiO)
Dorsoproximal–plantarodistal 60° oblique (D60Pr–PlDiO)
Plantaroproximal–plantarodistal 45° oblique (Pl45Pr–PlDiO)
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purposes, to determine whether or not the growth plate was closed, for
differential diagnosis and for visualisation of proximal extremity bones.
Distal extremity damage was detected in 140 (49.64%) horses, while no
pathology was noted in 142 (50.35%) of the horses that underwent X–ray.
A total of 140 thoroughbred British (n=66) and Arabian (n=74) horses
with distal extremity lesions detected upon clinical and radiological
examination were included in the study. Of these horses, 53 (25 British
and 28 Arabian horses) were female and 87 (42 British and 45 Arabian
horses) were male. The age of the horses in the study ranged 2–11
years. Among the horses included in the study, 119 (85%, 56 British
and 63 Arabian horses; 45 female and 74 male) had lesions in the
forelimbs and 21 (15%, 10 British and 11 Arabian horses; 8 female and
13 male) had lesions in the rear limbs.
In this study, more than one lesion was detected in 18 horses upon
clinical and radiological examination. Accordingly, 4 and 14 horses
had multiple lesions in the rear limbs and forelimbs, respectively.
Among the horses with >1 lesion in the forelimb, 2 had exostosis
of metacarpus (Mc) and DMD, 1 had Mc IV fracture and DMD, 4 had
sesamoiditis and sesamoid fracture, 3 had sesamoiditis and osselet,
1 had sesamoiditis and form (ringbone), 2 had osteoarthritis and
intraarticular fracture in the carpal joint, and 1 had sesamoiditis and
DMD. Of the 4 horses with rear limb lesions, 2 had bone spavin and
osteochondritis dissecans, 1 had sesamoiditis and form (ringbone),
and 1 had sesamoiditis and sesamoid fracture together.
The horses included in the study were presented with certain clinical
complaints, such as lameness, increase in lameness after strenuous
exercise, decrease in lameness after training, stumbling in races and
training, frequent foot changes, local swellings, and poor performance.
The lesions identied at the front and hind extremities as a result of
clinical and radiological examination are listed in TABLES II and III.
Upon clinical examination, regional temperature increase and
swelling were evident in all cases presented to the hospital in the
acute stage, and temperature and swelling varied by case. In addition,
varying degrees of lameness were observed in all cases; however, it
was more prevalent in horses with multiple lesions than in those with
a single lesion. The lameness scores are given in TABLE IV.
In cases involving the joint region (osteoarthritis, osselet,
intraarticular fracture, osteochondritis, and other ones), effusion
was found to be remarkable. It was observed that effusion was more
prevalent in horses presented after racing and training. With regard
to intraarticular fractures of the distal interphalangeal joint, the
fracture fragment was located in the processus extensorius of the
distal phalanx. Clinical examination of the cases with joint region
involvement revealed that pain intensied when the joint was exed.
In these cases, lameness also increased in horses that were trotted
up by exion test. Based on these clinical examination ndings, X–
ray images of the area with pain were acquired from the positions
specied in TABLE I.
The lesions with damage based on X–ray ndings are listed in
TABLES II and III. Images of certain cases with lesions in the distal
extremity upon examinations are shown in FIGS. 1, 2 and 3.
Pain was localised by regional anaesthesia in cases of reactive horses
(touch–sensitive horses) and where lameness could not be localised
upon clinical examination. Complete disappearance of lameness or
decreased lameness was considered positive and pain was localised
TABLE II
Distribution of lesions detected in the front limb
Region Determined lesion (n) Breed (A/B) Sex (F/M) Age range
% ratio in
front limb
% ratio among
total lesions
Carpus
Carpal III ssure (8) 3/5 2/6 3–7 6.01 5.06
Intraarticular fracture (5) 4/1 2/3 3–7 3.75 3.16
Osteoarthritis (29) 15/14 13/16 4–11 21.80 18.35
Metacarpus
Metacarpus II fracture (4) 2/2 0/4 4–6 3.00 2.53
Metacarpus IV fracture (2) 1/1 1/1 3–7 1.50 1.26
Incomplete fracture of metacarpus III (5) 2/3 1/4 4–6 3.75 3.16
Sore Shine(DMD) (21) 11/10 11/10 2–3 15.78 13.29
Suros (Splint) (8) 4/4 2/6 2–5 6.01 5.06
Fetlock
Osselet (14) 8/6 6/8 4–8 10.52 8.86
Sesamoid fracture (7) 3/4 2/5 3–7 5.26 4.43
Sesamoiditis (12) 7/5 5/7 2–5 9.02 7.59
Ligament calcication (4) 3/1 1/3 4–8 3.00 2.53
Pastern Form (Ringbone) (8) 3/5 4/4 4–8 6.01 5.06
Hoof
İntra articular fracture (2) 0/2 0/2 5–8 1.50 1.26
Distal phalanx fracture (4) 3/1 1/3 4–7 3.00 2.53
Total 133 69/64 51/82 2–11 84.17
A: Arabian horse, B: British horse, F: Female, M: Male
Evaluation of Distal Extremity in Racehorses / Ersöz-Kanay et al. ___________________________________________________________________
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TABLE III
Distribution of lesions detected in the hind limb
Region Determined lesion (n) Breed (A/B) Sex (F/M) Age range
% ratio in
hind limb
% ratio among
total lesions
Hock
Bone spavin (4) 2/2 2/2 4–6 16 2.53
Osteochondritis dissecans (8) 4/4 3/5 2–3 32 5.06
Metatarsus Suros (Splints) (5) 3/2 2/3 4–7 20 3.16
Fetlock
Osselet (2) 1/1 1/1 4–5 8 1.26
Sesamoid fracture (1) 1/0 0/1 5 4 0.63
Sesamoiditis (3) 1/2 1/2 2–3 12 1.89
Pastern
Form (Ringbone) (2) 1/1 1/1 6–7 8 1.26
Total
25 13/12 10/15 15.82
A: Arabian horse, B: British horse, F: Female, M: Male
TABLE IV
Distribution of lameness scores according to cases
Lameness
score*
Diagnosis
Number
of cases
Total
1
Suros (Splints) 1 1
2
Suros (Splints) 2
8
Sore–shine 3
Sesamoiditis 2
Osselet 1
3
Suros (Splints) 6
50
Sore–shine 18
Metacarpus II fracture 3
Metacarpus IV fracture 1
Ligament calsication 4
Osselet 15
Bone spavin 1
Form (Ringbone) 2
4
Osteoarthritis (Carpus) 16
53
Suros (Splints) 4
Sesamoiditis 13
Form (Ringbone) 8
Bone spavin 3
Intraarticular fracture (Carpus) 2
Intraarticular fracture (Hoof) 1
Osteochondritis dissecans 4
Metacarpus II fracture 1
Metacarpus IV fracture 1
5
Osteoarthritis (Carpus) 13
46
Incomplete fracture of metacarpus III 5
Sesamoid fracture 8
Intraarticular fracture (Carpus) 3
Intraarticular fracture (Hoof) 1
Osteochondritis dissecans 4
Carpal III ssure 8
Distal phalanx fracture 4
Total 158 158
* AAEP lameness scale was used [4]. Lameness score 0: No lameness. 1: It is dicult to observe
lameness. On a mount, it is not consistently visible on hard surfaces when longitudinal. 2: It is dicult
to observe lameness while walking or running in a straight line. However, it can be detected on hard
surfaces while riding, longing. Lameness is not always evident. 3: Lameness is evident at a certain
speed. 4: The lameness is evident even in walking. 5: Lameness is evident both in motion and at rest.
based on these regions. The test was positive in all horses (n=12) that
received regional anaesthesia. Regional anaesthesia was used to
localise the pain and radiological examination revealed sesamoiditis,
osselet, carpal joint osteoarthritis and distal phalanx fracture.
Clinical and radiological examination revealed that the degree
of lameness was higher in cases with intraarticular lesions, bone
fractures and multiple lesions. The lameness scores of all cases are
given in TABLE IV.
Distal limb lesions cause varying degrees of lameness, ranging
from barely visible to severe lameness. Especially in racehorses,
lameness or inadequate and deficient performance associated
therewith adversely affects the racing life of the horse. Diagnosis of
lameness caused by distal extremity lesions requires a comprehensive
examination, including a careful inspection and palpation, manipulative
tests, careful examination of the shoe nail and regional anaesthesia.
However, the diagnosis requires technical imaging modalities to fully
assess the specic causative lesions [1, 2]. Radiology is an important
diagnostic method for determining the normal postural position,
bone–joint relationships and bone lesions in horses [2, 5, 6]. It is also
one of the most widely used imaging modalities in the diagnosis of
limb bone disorders in horses [2]. Radiological examination plays an
important role in both the diagnosis and treatment of degenerative
joint and bone damage. Osteophytic formations around the joint, in the
joint capsule, and at tendon–ligament–bone junctions, irregularities
in the periosteum and bone lysis can be visualised via radiological
examination. To examine lower extremity lesions and small volume
bone lesions in horses through radiological examination, it is critical
to know the radiographic positions during the procedure and to take
radiographs in several directions rather than a single radiographic
position to ensure accurate diagnosis and treatment [3].
The structure of the forelimb in horses is critical for the horse's
overall athletic performance and susceptibility to lameness, as it
carries approximately 55–60% of the body weight of a standing horse.
During races or strenuous exercise, the front extremities are exposed
to more stress than the rear [3, 7, 8]. In this study, 85% of the horses
had lesions in various parts of the forelimbs (n=119), whereas 15% had
lesions in various parts of the rear limbs (n=21).
FIGURE 1. a–c. Some cases observed in the carpal joint. a. Flexed LM radiographic
view of the carpal joint. b. LM view of the carpal joint. a,b: Osteophytosis and
lysis in carpal bones and distal radius due to osteoarthritis are shown. c. In the
D30Pr–DDiO radiographic view of the carpal joint, the ssure formed in the
carpal III bone is shown between the arrows. d–f. Some cases determined in
the metacarpus. d. In the D55L–PaMO radiographic position of the metacarpus,
periostitis formed at the level of the middle one–third of the mediolateral of the
metacarpal 3 and a broken arrow formed in the distal of the metacarpal 4 are
shown. e. In the radiographic position of D55L–PaMO, periostitis due to sore–
shine and osteoperiostic osteophytosis in the middle third of the mediolateral
aspect of the dorsal surface of the metacarpus are shown by the arrow. f. In
the DPa imaging of the metacarpus, osteophytic growths (Suros) formed on the
medial side between the middle and upper 1/3 of the Metacarpal 3 are shown
FIGURE 2. Metacarpophalangeal joint (fetlock) and some cases with lesions more
distally. a. A case of calcication in the distal sesamoidan ligament identied in
the LM radiographic view of the metacarpophalangeal joint (indicated by the
arrow). b. D45M–PaLO radiographic view of the pastern region, the case of the
form (ringbone) formed in the proximal phalanx and phalanx media and the
enlarged vascular channels formed in the lateral sesamoid (indicated by arrows).
c. In the D45L–PaMO radiographic view of the fetlock, osselet formed on the
dorsolateral surface, enlarged vascular channels due to sesamoiditis formed
in the medial sesamoid and entesophyte case formed around the sesamoid
(osteophytic growths and enlarged vascular channels are shown with arrows).
d–f. Some cases seen in proximal sesamoid bones. d. A case of sesamoiditis and
osselet in the D45L–PaMO radiographic view of the fetlock: Enlarged vascular
canal in the sesamoid bone (shown by thin white arrow), osteophytic areas
formed around the sesamoid bone (shown by thick white arrows), osteophytosis
forming dorsolateral to the fetlock (shown by gray arrow). e. A case of sesamoid
fracture due to sesamoiditis detected in D45M–PaLO radiographic view of fetlock
(enlarged vascular channels are indicated by thin white arrow and sesamoid
fracture by thick white arrow). f. Fracture case of proximal medial sesamoid
bone detected in D30Pr–PaDi radiographic view of fetlock (indicated by arrows)
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a b
a b
c d
e f
c
d
e
f
FIGURE 3. Radiographic view of the incomplete fracture formed in Metacarpal
III of the same case (a and b) in dierent positions. In the radiographic view of
the region (a. D45–70Pr–DDiO, b. DPa), intraarticular parasagital fracture formed
in the dorso–lateral aspect of the distal metacarpus are shown by arrows. c.
osteoarthritis and osteochondritis dissecans (OCD) and bone spavin case seen in
hock. In the D55M–PlLO radiographic view of the tarsal joint, the bone fragment
fractured from the distal end of the tibia is shown with thin small white arrows
between the ends of two thick arrows, and periostitis formed in the tarsal
bones medial to the tarsal joint. d. Distal phalanx fracture case. D60Pr–RaDiO
radiographic position of hoof, the fracture line of the distal phalanx formed in
the processus palmaris lateralis is shown with the tips of two arrows
a b
c d
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already been signicant [9, 11]. Unidirectional radiographic position is
insucient for the radiological examination of the distal extremities
and more than one radiographic view are necessary for a proper
radiographic assessment (Table I). In a study on 114 horses with
lameness complaints, Steel et al. [15] reported that 28% of the horses
had forelimb lameness and that carpal osteoarthritis accounted for
56% of these cases. Himani et al. [1] reported that carpal region lesions
constituted 7.26% of the lesions they identied in a study involving
78 horses with lameness and that the age of the horses ranged 4–15
years. They reported that carpal osteoarthritis accounted for 66.6%
of the carpal region lesions. In the present study, carpal joint lesions
(n=42 lesions, 40 horses, 28.57%) included osteoarthritis (n=29),
intraarticular fracture (n=5) and ssure in carpal III (n=8). The horses
with carpal joint lesions were aged 4–11 years. The most prevalent
carpal joint lesion was osteoarthritis (n=29, 69.04%). Two horses
had carpal osteoarthritis and intraarticular fracture. Upon clinical
examination of horses with carpal osteoarthritis, lameness and pain
varied according to the degree of damage to the joint. Lameness and
pain on exion were more prevalent in horses with both osteoarthritis
and intraarticular fractures. Cases with ssures in the carpal joint
bones (carpalIII) and three other cases of intraarticular fractures could
be cases where osteoarthritis was not fully detected on radiography
but the bone structure had already begun to deteriorate.
DMD is one of the most important causes of poor performance in
racing and exercise in young racehorses. DMD, popularly known as
sore shin, occurs more frequently in the early stages of beginning
strenuous exercises [16]. It was reported to affect 70% of thoroughbred
racehorses in training [17]. Initial clinical signs include mild swelling
of the dorsal and sometimes dorsomedial aspect of the metacarpus
III (Mc III) and pain on palpation. Exposure to cyclic sustained fatigue
can involve various pathological changes on the dorsal or dorsomedial
surface of the Mc III, including periostitis, new bone formation, lysis
of the cortex, and stress fractures [16, 17]. In this study, DMD was
diagnosed in 21 cases (13.29%). Most of these cases (n=17) had higher
sensitivity on palpation at the middle 1/3 level of the metacarpus. In
the other 4 cases, higher sensitivity was determined in the distal 1/3.
Periostitis was noted in 15 and osteophytosis in 6 cases with DMD. All
horses with DMD were young (2–4 years). The young age of the horses
with DMD included in the study suggested that strenuous exercise
might have started at a time when bone maturity was not fully formed
or that strenuous exercise was started rapidly rather than gradually.
Mineralisation (ossification or calcification) of the tendons
and ligaments is one of several possible histological features of
desmopathy and tendinopathy, and its incidence in horses is rare.
Inammation in the tendons and ligaments causes degeneration
and swelling of collagen bundles. Treatment interruption or failure
and continuous traumas cause the inammation to progress and
character followed by dystrophic calcication [18]. Radiography is
frequently used for the diagnosis of dystrophic calcication [19]. In
this study, distal sesamoid ligament calcication was observed in 4
cases (2.53%). This may be associated with chronic desmitis.
In thoroughbred racehorses, stress fractures, carpal and
metacarpophalangeal / metatarsophalangeal (MCP/MTP) joint injuries
are important causes of morbidity [12]. Hyperextension in strenuous
exercises such as galop or racing in sports arenas may lead to
signicant stress on the MCP joint. This may increase the sensitivity of
Osteoarthritis is one of the causes of poor performance, pain,
disability and economic loss in racehorses [9, 10, 11, 12], occurs
mostly at the carpal and metacarpophalangeal joints in racehorses
and accounts for approximately 60% of lameness in horses [10, 12]. In
racehorses, it may occur both at early and advanced ages [10]. Carpal
osteoarthritis is a condition characterised by degeneration of the
joint bones, thickening of the joint capsule and associated restricted
joint motion and pain in exion [12, 13]. Osteoarthritis increases the
severity of synovial membrane inammation by affecting the integrity
of the articular cartilage and is important because it causes brosis of
the joint capsule and periarticular muscle weakness [9, 13, 14]. Early
diagnosis is important to prevent and treat severe joint damage [9,
13]. Radiology is an important diagnostic method for joint and bone
lesions. Although osteochondral damage, fractures, subchondral
bone lesions, osteoarthritis and osteochondritis dissecans (OCD)
are prevalent in horses, these conditions are generally detected via
radiological examination. Radiographic changes in osteoarthritis
develop slowly, and when diagnosed, the damage to the bone has
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the MCP joint [20]. In racehorses, conditions such as osselet, aseptic
and septic joint inammations, sesamoiditis, fractures in the bones of
the region, soft tissue damages [21] and mineralisation or calcication
in soft tissues occur in MCP/MTP regions [18]. Osselet can also be
described as traumatic osteoarthritis of the MCP/MTP joint; it involves
an aggregation of pathological and clinical manifestations that occur
in and around the joint as a result of single or repeated trauma to the
MCP/MTP joints [21] and is characterised by hypertrophic proliferation
of the dorsal capsule of the joints in question [22]. Conditions such
as synovitis, capsulitis, joint inammations, suspensory ligament
damages, intraarticular fractures and subchondral bone fractures
in the region may cause osselet formation [21]. It may occur in the
front and hind extremities. However, it is usually more prevalent in the
forelimbs. In this study, osselet was observed more frequently in the
anterior extremity; the anterior extremity and the posterior extremity
were involved in 14 cases (8.56%) and 2 cases (1.26%), respectively.
Sesamoiditis is a condition characterised by enlargement of
the vascular canals of the proximal sesamoids, local osteolysis,
osteophytic growth and enthesophyte formation. Sesamoiditis leads
to a decrease in exercise performance, especially in racehorses
[2, 22]. More than one sesamoid and therefore more than one
limb can be concurrently involved. Although the aetiology of this
condition has not yet been completely understood [20], it has been
reported that the vascular structure of the proximal sesamoid bones
could be easily affected by trauma [2]. There are suggestions that
rupture or damage of the suspensor ligament, sesamoid ligament
and intersesamoid ligaments affect the formation of sesamoiditis
[22]. The distal sesamoid ligament extends from the base of the
sesamoid bone to the rst phalanx. Inammation of this ligament
may result in evident lameness in horses. Calcication in the ligament
may also be observed in certain chronic inammatory conditions
[20]. A study by Seghrouchni et al. [22] reported that sesamoiditis
and ligament calcification occurred a rate of 44.09 and 8.06%,
respectively. Furthermore, exposure to excessive hyperextension
of the ligaments and tendons in the MCP/MTP joint region, trauma
to the sesamoid bones, or any inammation in the sesamoid bone
may cause sesamoid bone fractures [22]. In this study, there were
9.49% of sesamoiditis (9.02% forelimb, 1.89% rear limb), 5.06% of
sesamoid bone fracture (4.53% forelimb, 0.63% rear limb) and 2.53%
of ligament calcication (forelimb) cases as revealed via radiological
examination. The higher load and stress on the forelimb may explain
why most of the lesions occurred in the forelimb.
The form is characterised by osteophytic growths as a result of
periostitis on the dorsal, medial and lateral sides of the phalanges
distal to the MCP/MTP joint [2, 23]. Upon examination, the pain is more
intense, especially when the area is moved and rotated. It may lead
to varying degrees of lameness [2]. It was reported that periostitis
caused by inammation and stress of the ligament joints in the region
was effective in the occurrence of the form. Osteophytic proliferations
that occur due to periostitis may cause osteoarthritis and ankylosis
in the buccal joints [23]. In a study conducted by Semieka and Ali
[23] on donkeys (Equus asinus), it was reported that the same were
more prevalent in the anterior extremities (16 cases in the anterior
extremities and 4 cases in the posterior extremities). Similarly, Himani
et al. [1] reported that the same were more prevalent in the forelimb
(66.67%). In the present study, the rates were 5.06% (n=8) in the
forelimb and 1.26% (n=2) in the rear limb.
Distal phalanx fractures are frequently encountered in horses during
racing or due to impact with a hard surface. The fracture may be caused
by a shock and stress inside the nail. In such cases, a sudden lameness
may occur. Lameness is severe in intraarticular fractures but may be
less severe in fractures of the lateral wall not connected to the joint.
Distal phalanx fractures are more prevalent in the forefoot but are also
prevalent in the rearfoot [22, 24]. Intraarticular fractures are easily
diagnosed and the resultant lameness is usually associated with joint
effusion. The lameness could be localised by pain identied during
examination of the nail with an examination forceps in extra–articular
fractures. Lameness is aggravated when on lunge or when turning the
horse on the affected leg. Clinical symptoms may suggest the possibility
of fracture. However, the denitive diagnosis is conrmed by palmar
digital nerve block and radiographic imaging. It can be dicult to
diagnose based on a radiograph taken immediately after the injury.
This is because the fracture is merely similar to the size of a hairline
at this stage or the x–ray beam is not tangential to the fracture line
[24]. Therefore, it may be necessary to repeat the radiographic study
including varying angles a few days or a week later [20, 24, 25]. In
this study, distal phalanx fracture was detected in 6 cases (3.79%),
of which 2 were intraarticular fractures (1.26%) and 4 were extra–
articular fractures (52.53%). All cases with distal phalanx fractures
were observed in the forelimb, and intraarticular fractures were found
in the processus extensorius region of the distal phalanx. This may be
due to hyperextension and overstretching of the musculus extensor
digitorum communis tendon during racing and exercise.
Bone spavin is a degenerative osteoarthritis condition characterised
by periostitis and osteitis in the os tarsale tertium and centrale bones
of the tarsal joint. It is common in older horses and ponies and is a
prevalent cause of rear leg lameness [1, 2]. The lameness may vary from
mild to severe with dragging the nail tip and has a cold intermittent
character. One or both rear limbs may be affected. X–ray images
from the affected joints can show a wide range of bone degeneration
and damage that does not always correspond directly to the degree
of lameness in question. The diagnosis of bone spavin is based on
physical and radiological examinations [1, 2, 20]. In this study, bone
spavin (2.53%) was found in 4 cases with varying degrees of lameness.
OCD is a developmental orthopaedic disease of the equine joints.
It is one of the leading causes of lameness and reduced performance
in young athletic horses. Articular cartilage does not normally occur
in these horses. This results in lesions in the cartilage and bone and
leads to the development of free–oating bone fragments or cartilage
fragments within the joint. Rapid growth and high–calorie diets
are prevalent causes of OCD. Unbalanced diets that fail to provide
sucient minerals may also increase the risk of OCD. Clinically,
effusion is seen in the joint area. Lameness can be of varying degrees.
The denitive diagnosis is determined via radiological examination
[26]. In this study, there were 8 (5.06%) cases of OCD. Radiographs
of all of these cases revealed that the fragments identied in the
tibiotarsal joint were separated from the distal part of the tibia.
CONCLUSION
In conclusion, lesions of the forelimbs are more prevalent in
racehorses than those of the rear limbs, and this may be attributed
to higher load and stress intensity on the forelimbs. Radiological
Evaluation of Distal Extremity in Racehorses / Ersöz-Kanay et al. ___________________________________________________________________
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examination is a highly useful and important diagnostic method in the
denitive diagnosis and treatment of bone lesions and in the follow–
up of treated cases. Although there has been extensive progress
in diagnostic imaging in recent years, radiography still remains a
satisfactory imaging technique for diagnostic imaging of the distal
extremity in horses owing to its cost–effectiveness.
Funding support
The study was supported by Dicle University Scientic Research
Projects Coordination Oce with the infrastructure project titled
"Equine Medicine and Creation of Hippotherapy Infrastructure of
Dicle University Faculty of Veterinary Medicine" with the project code
VETERINER.18.008.
Conict of interest
The authors report no conicts of interest. The authors alone are
responsible for the content and writing of this article.
ACKNOWLEDGEMENTS
We would like to thank the staff of Dicle University Scientific
Research Projects Coordinator, Diyarbakir Hippodrome Directorate
and Horse Hospital.
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