Revista Cienﬁca, FCV-LUZ / Vol. XXXV Recibido:08/07/2025 Aprobado:26/08/2025 Publicado: 26/09/2025 hps://doi.org/10.52973/rcfcv-e35650 UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico 1 of 5 Revista Cienﬁca, FCV-LUZ / Vol. XXXV hps://doi.org/10.52973/rcfcv-e35744 UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico Clinical and radiological evaluaon of bucked shin cases in race horses Evaluación clínica y radiológica de casos de bia arqueada en caballos de carreras Emine Çatalkaya* , Berna Ersöz-Kanay Dicle University, Faculty of Veterinary Medicine, Department of Surgery, Diyarbakir/TURKİYE. *Correspondent author: eminecatalkaya21@gmail.com ABSTRACT Bucked shin is a common condion that primarily aﬀects young racing and fast-walking horses and causes exercise intolerance. It is usually characterized by pain and swelling in the dorsomedial surface of metacarpal III. This study contributes to the pracce of horse medicine by evaluang the cases of bucked shin encountered during a racing season. The study material consisted of thoroughbred Arabian and English racehorses (n=19) aged 2-4 years old brought to the Diyarbakır Hippodrome Directorate Horse Hospital with complaints of stumbling, swelling on the dorsal and dorsomedial surface of the metacarpus, sensivity, frequent foot changes during training, and training intolerance during a racing season. Based on the clinical and radiological examinaons of the horses included in the study, local perioss and osteolysis were determined in 7 cases, stress fracture in 2 case, exostosis in 7 cases, and thickening of the bone cortex in 6 cases. It was learned from the horse owner that 2 4-year-old horses evaluated within the scope of the study had been treated before, but had relapsed. Relapse occurred in 1 case treated within the scope of the study. In one case, an open metacarpus fracture occurred during a race aﬅer being diagnosed with bucked shin. As a result, bucked shin cases can be frequently encountered in young and under-trained horses and this situaon should be taken seriously. Since ignoring the stress and lesions in the metacarpal III bone can cause fractures and major disasters, it can be said that this situaon can be prevented by exercising the horse in controlled and suitable condions during the foaling period. Key words: Distal extremity; metacarpus; perioss; racehorse RESUMEN La bia arqueada es una patología común que afecta principalmente a caballos jóvenes de carreras y de paso rápido, y causa intolerancia al ejercicio. Generalmente se caracteriza por dolor e inﬂamación en la superﬁcie dorsomedial del tercer metacarpiano. Este estudio tuvo como objevo, contribuir a la prácca de la medicina equina mediante la evaluación de los casos de bia arqueada detectados durante una temporada de carreras. El material de estudio consisó en caballos de carreras pura sangre árabes e ingleses (n=19) de 2 a 4 años de edad, llevados al Hospital Ecuestre de la Dirección del Hipódromo de Diyarbakır con sintomas de tropiezos, inﬂamación en la superﬁcie dorsal y dorsomedial del metacarpo, sensibilidad, cambios frecuentes de pie durante el entrenamiento e intolerancia al entrenamiento durante una temporada de carreras. Con base en los exámenes clínicos y radiológicos de los caballos incluidos en el estudio, se determinó perioss local y osteólisis en 7 casos, fractura por estrés en 2 casos, exostosis en 7 casos y engrosamiento de la corcal ósea en 6 casos. Uno de los propietario informó que dos de sus caballos de 4 años evaluados en el marco del estudio habían recibido tratamiento previo, pero habían sufrido una recaída. Asimismo, un caso tratado en el marco del estudio presentó una recaída. En un caso, se produjo una fractura expuesta de metacarpo durante una carrera tras ser diagnoscado con bia arqueada. Por lo tanto, los casos de bia arqueada son frecuentes en caballos jóvenes y poco entrenados, y esta situación debe tomarse en serio. Dado que ignorar el estrés y las lesiones en el tercer metacarpiano puede causar fracturas y graves consecuencias, se puede aﬁrmar que esta situación se puede prevenir ejercitando al caballo en condiciones controladas y adecuadas durante el período de parto. Palabras clave: Extremidad distal; metacarpo; perioss; caballo de carreras

Revista Cienﬁca, FCV-LUZ / Vol. XXXV UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico INTRODUCTION Bucked shin is a painful condion caused by perioss that occurs due to stress and fague on the dorsal surface of metacarpal III and/or metatarsal III in young racehorses and fast-walking horses (Eqqus caballus) [1 ,[2]. It is referred to as dorsal metacarpal disease in some sources. Because it is more frequently deﬁned as perioss characterized by pain on the dorsal and dorsomedial surfaces of the metacarpal III bone [1 , 3]. Bucked shin is usually observed bilaterally and the extremies are usually aﬀected in order. The direcon in which racehorses are trained is important. For example, in horses trained and raced clockwise, the right extremity is aﬀected ﬁrst, followed by the leﬅ extremity [4]. The metacarpus is an integral part of the shock-absorbing, weight-bearing system of the forelimb. Excessive body weight and the fact that the majority of the body weight is carried by the front extremies, the thin structure of the metacarpus relave to the body structure and weight, among others, cause stress and fague in the metacarpus in young racehorses in training [4]. The metacarpal bone is less rigid in young horses and therefore, greater strains occur in the dorsal cortex during high- speed exercise than in older horses. This situaon causes pain as a result of high-tension cyclic fague caused by excessive stress on the bone on the dorsal surface of the metacarpus. A new bone layer formaon can form on the stress line in the stressed metacarpus. This new bone ssue is weaker. This situaon causes inﬂammaon in the periosteum and pain due to inﬂammaon [1 , 3]. Bucked shin is one of the most common causes of loss in young racehorses during training and race days. This condion, commonly known as “bucked” or “sore” shinbone, is inially very painful. It usually occurs early in training and can cause concern for horse owners [3]. The aim of this study is to evaluate cases of bucked shin in young racehorses that do not have a speciﬁc treatment during a race season (7 months) and to contribute to equine pracce. MATERIALS AND METHODS The study material consisted of 19 racehorses of Arabian and English racehorses and 2-4 years old brought to the Diyarbakır Hippodrome Directorate Equine Hospital with complaints of stumbling during racing and exercise, frequent foot changes, local swelling, curvature (convexity) and local tenderness on the dorsal surface of metacarpal III. Aﬅer clinical examinaon of the horses, radiographs were taken with a CR X-ray device (Fujiﬁlm FCR Prima T2 Veterinary Set, Japan) in the mediolateral, dorsopalmar lateromedial oblique posions and horses diagnosed with bucked shin were included in the study. Perioss, exostosis, and thickening of the bone cortex were determined on the radiograph. All but one case diagnosed with bucked shin were treated. Cold hydrotherapy, 3 doses of local subcutaneous corcosteroid (Dexamethasone, Dekort ampoule 8 mg/2 mL, Deva, Turkiye) injecons every other day (d), rest and controlled exercise aﬅer treatment, and a longer period of rest (1 month) was recommended for cases with stress fractures. In cases where bone curvature (convexity) and thickening of the bone cortex were determined, cold hydrotherapy and 3 doses of nonsteroidal an-inﬂammatory injecons (Phenylbutazone, Equi-Butazone, Alivira, Turkiye) were applied unl local heat and regional inﬂammaon symptoms were eliminated, then cryosurgery was performed and a protecve dressing was applied for 1 week. In cases where bone growth was formed, point cauterizaon was performed aﬅer rest and medical treatment and a protecve dressing was applied for 10 d. Protecve dressings were renewed at 3-d intervals. During the protecve dressings and unl the wounds healed, the horses were ed up and suspended. Aﬅer the cryotherapy and cauterizaon procedures, a protocol of 1 week of complete rest, 1 week of walking, and 1 week of riding was applied to the horses, and then gradual training (gradual from light to strenuous exercise) was recommended. In cases with stress fractures, the rest period was kept longer. Aﬅer the fracture healing was achieved in radiological controls, they were allowed to train. RESULTS AND DISCUSSION The 19 horses included in the study were Purebred Arabians (n=10) and English horses (n=9). 8 of the Arabian horses were 3 years old and 2 were 4 years old. All of the English horses were 2 years old. It was learned from the anamnesis that the 4-year-old Arabian horses had bucked shin aﬅer starng their ﬁrst intensive exercises and had been treated before, but had relapsed again. Clinical examinaon revealed that the cases mostly occurred on the dorsomedial side of the metacarpus and all had local pain. Regional warmth was present in all cases except for the 2 cases that recurred. Radiographic examinaon revealed local perioss on the dorsomedial side of the metacarpus in 7 cases (FIG. 1), stress fractures in 2 cases (FIG. 2), bone proliferaons in 7 cases, and thickening of the bone cortex in 6 cases. All of these ﬁndings were also present in cases where they occurred together. In one case (FIG. 2), stress fracture, bone proliferaon and thickening of the bone cortex were detected together, and in another case (FIG. 3), local perioss and stress fracture were detected. All cases were observed in the front extremies. It was determined to be unilateral in 13 cases and bilateral in 6 cases. In one case in which perioss was detected in radiographic examinaon and treatment was not requested by the paent’s caregiver (FIG. 1), an open metacarpus fracture occurred while running a race 2 weeks aﬅer the diagnosis was made. 2 of 5

Bucked shin cases in race horses / Çatalkaya y Ersöz-Kanay UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico FIGURE 1. Radiographs of a bilateral bucked shin case detected in a 2-year-old English horse. Black arrows show local perioss on the metacarpal surface, white arrows show swelling and curvature (convexity) on the skin surface FIGURE 2. Radiogram of a bucked shin case detected in a four-year-old Arabian horse. In this case, there is thickening of the bone cortex between the thin white arrowheads, the thick white arrow shows local bone proliferaon, and the black arrow shows a stress fracture formed due to the bucked shin FIGURE 3. Radiograph of a case with local perioss and stress fracture in a three-year-old Arabian horse. The white arrowheads show signs of irregularity and inﬂammaon in the periosteum, while the black arrow shows the stress fracture due to damage to the bucked shin and bone In one of the 5 cases with local perioss and treated with hydrotherapy and local corcosteroids, cryosurgery was performed as a second treatment because of the persistence of local pain and exercise intolerance. In the 2 cases with recurrence at the age of 4, it was determined in the anamnesis that cryosurgery had been performed before, and point cauterizaon was applied as a second treatment. No recurrence was encountered aﬅer the treatments. Dorsal metacarpal pain is one of the most common injuries aﬀecng young racehorses and somemes horses that have not been exercised or competed intensively. It is usually observed more in the forelimbs [1 , 3 ,5,6,7]. Inially, lameness may not be seen, but there is tenderness on palpaon of the dorsal and/ or dorsalmedial cortex of metacarpal III [3 ,5]. It is reported that it constutes 24.1% of all musculoskeletal injuries in these horses [8] and that approximately 70% of horses starng compeon exercise may be aﬀected [3 ,9]. The young horses evaluated in this study and the pain on the dorsomedial surface of metacarpal III are parallel to these studies. However, since its prevalence among musculoskeletal diseases was not examined, comparison could not be made. The disease has an acute onset and becomes most pronounced aﬅer intense exercise. There is usually a minimal change in the horse’s 3 of 5

Revista Cienﬁca, FCV-LUZ / Vol. XXXV UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico gait, especially aﬅer short rest periods. A visible convex swelling covering the surface of the aﬀected part of the metacarpus can be seen. On palpaon, the dorsal cortex of metacarpal III is painful to pressure. Oﬅen the horse withdraws its leg in response to pain [1 , 3]. Somemes no pathology can be detected on radiographs taken in the acute phase; however, fractures and minimal superﬁcial corcal osteolysis, perioss can somemes be detected [1 ,[10]. In this study, local perioss and mild osteolysis were detected in 6 cases with local temperature increase and tenderness, and no fractures were encountered. It is emphasized that the reason for pain in the metacarpus in young horses is that the bone of the metacarpus is soﬅer than in adult horses and therefore, stress occurs in the dorsal cortex during high-speed exercises. It is reported that pain occurs due to excessive stress in the dorsal and dorsomedial parts of the metacarpus and causes the formaon of a new bone layer in this region and that the newly formed bone ssue is weak and may be prone to fracture [1 , 3]. Gray et al. [11] and Rigss [12] emphasized in their studies that the causes of metacarpal bone fractures are not fully known, catastrophic fractures in racehorses are not spontaneous events, and stress fractures may be related to bone damage and repair. A relaonship between complete fractures and dorsal cortex stress fractures has also been reported in some studies [11 , 13 , 14]. Metacarpal III is one of the bones most frequently aﬀected by stress fractures. In addion, when racehorses that start training are started on high-speed exercises, the dorsal cortex of MC III is usually aﬀected, and as a result, dorsal cortex stress fractures may develop in some horses [11]. In this study, stress fractures occurred in 2 cases, and an open fracture was detected in 1 case during the race. It can be said that in the case where an open fracture occurred, it may be due to the paent’s reluctance to receive treatment and connuing to do intense exercise, and that this situaon may be due to the weakening of metacarpus III due to inﬂammaon. The diagnosis of bucked shin can be easily made with clinical examinaon and auxiliary imaging techniques. Radiography can help idenfy pathologies formed in metacarpal III [1 , 3]. For this purpose, radiographs can be taken in dorsopalmar (DP), lateral- medial (LM), dorsal palmar lateral medial oblique (DPLMO) and dorsal palmar medialolateral oblique (DPMLO) posions [1 , 3 , 15]. DPLMO and LM best determine dorsal medial bone proliferaon, and DPMLO and LM best determine dorsal lateral cortex fractures. Horses that connue to exercise and compete with bucked shin pain are predisposed to fracture development [1 , 3]. In this study, radiographs were mostly taken in LM and DPLMO posions, and most of the lesions were determined in the dorsomedial part of metacarpus III. Therefore, in cases of bucked shin, radiographic examinaon may be recommended in lateromedial and dorsopalmar oblique posions. Racehorses have thin and delicate legs according to their body structure. McCarthy and Jeﬀco [16] emphasized in their study that horses that completed the training program without any fractures had more mineral bone content and that the exercises that the foals did with age signiﬁcantly increased the mineral density of the metacarpal bone and that lack of exercise delayed normal bone development. During the rigorous training of young racehorses, the stress on the long bones oﬅen increases and the biological response may cause a curvature on the dorsal surface of metacarpal III without inﬂammaon. When the curvature on the dorsal surface of the metacarpus increases or progresses, intensive exercise cannot be performed even though race training is very important for the horse’s career. Therefore, early diagnosis is important [3], 10 , 17]. In this study, thickening of the bone cortex and curvature on the dorsal surface of the metacarpus were detected in 6 cases. This may be due to the fact that the paents’ caregivers did not noce the bone fague in the metacarpus due to the absence of lameness complaints and this fague may have resulted in thickening of the bone cortex aﬅer ongoing training. Age, breed, genec characteriscs, race track, age of starng exercise and intensity, among others are eﬀecve in the eology of scurvy. In a study conducted by Crevier-Denoix et al. [18], it was reported that a synthec track caused lower hoof acceleraon than grass and soil and also changed the angle at which the hoof entered the surface, Seerbo et al. [19] reported that the soil surfaces commonly used in the United States were the hardest and that dorsal metacarpal diseases were more common. A study conducted by Davies [20] reported that the track surface had no eﬀect on the frequency of dorsal metacarpal diseases in 16 to 19 month old Thoroughbreds in training. In this study, races and exercises were performed on a synthec sand track. Since it was the only sand track belonging to the Diyarbakır Hippodrome Directorate, comparisons could not be made with other tracks. CONCLUSION As a result, in horses that are training for compeon, high loads can create low cyclic fague in the bone, which can lead to microdamage or eventual bone failure. Horses with painful metacarpus should not be considered to lose a race day, and pain should not be taken lightly, and suﬃcient rest should be given to foals preparing for compeon. In addion, a good preparaon of the exercise program for foals preparing for compeon can prevent this situaon and training on soﬅ ground can be recommended. ACKNOWLEDGEMENT We would also like to thank the Turkish Jockey Club and Diyarbakir Hippodrome Directorate for their support in the conduct of this study and the use of the data obtained. Availability of data and materials The data that support the ﬁndings of this study are available on request from the corresponding author (EÇ). 4 of 5

Bucked shin cases in race horses / Çatalkaya y Ersöz-Kanay UNIVERSIDAD DEL ZULIA Serbiluz Sistema de Servicios Bibliotecarios y de Información Biblioteca Digital Repositorio Académico Conﬂict interests statement The authors declare that they have no conﬂicng interests. Informed consent It is declared that this study, whose informaon is given above, is among the studies that do not require ethics commiee approval, since it is a retrospecve study. BIBLIOGRAPHIC REFERENCES [1] Bertone AL. Metacarpus and metatarsus. In: Baxter GM, Editör. Adams & Stashak’s Lameness in Horses. 6th Ed. Wiley Blackwell: USA. 2011. p. 1182-1193. [2] Yanmaz LE, Okumuş Z. Thermographic assessment of extremity temperature alteraons of cases with bucked shin complex, splints, carpal osteoarthris and sesamoidis in sport horses. Erciyes Üniv. Vet. Fak. Derg. [Internet]. 2018 [cited 22 May 2025]; 15(1):41-45. 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