The characteristics of the muscles of the thoracic limb were evaluated in 22 specimens of Lycalopex gymnocercus. Descriptive and comparative analyses showed similarity with other canids in terms of topography and tendon insertions. Differences with the domestic dog were observed in the pectoralis profundus, triceps brachii and interflexorii muscles. Intraspecific variations were observed in the rhomboideus capitis, serratus ventralis cervicis, extensor carpi radialis, extensor digiti I and II, lumbricales, flexor digiti I brevis, abductor digiti I brevis, and flexor digiti V muscles. The analyses of muscle architecture carried out in nine specimens showed that there was no difference in muscle percentage mass in the thoracic limb of males and females, but a young specimen showed significant lower percentage mass. The triceps brachii caput longus muscle showed the greatest mass, the subscapularis muscle showed the greatest physiological cross‐sectional area value, and the extrinsic muscles, in general, presented the longest fascicles and higher architectural indexes. Muscle architecture data were compatible with those of a thoracic limb adapted to fast cursorial locomotion that prioritizes movements in a sagittal plane instead of rotation or adduction/abduction. There was a high association between functional percentage mass of the muscles in the thoracic limb and phylogeny in the Carnivora order. It may be inferred that carnivoran muscle mass is largely determined by phylogeny.

O Lycalopex gymnocercus (graxaim-do-campo) é um canídeo silvestre de médio porte que ocorre no cone sul. Tem dieta onívora e habita desde planícies descampadas até matas densas. A artéria celíaca é um dos principais ramos da aorta abdominal e possibilita a irrigação de importantes órgãos, tais como estômago, pâncreas, baço e duodeno. Objetivou-se estudar a topografia da artéria celíaca no L. gymnocercus, com ênfase em características comparativas e aplicadas. Para tal, foram dissecados, mensurados e radiografados 15 cadáveres de L. gymnocercus coletados mortos em rodovias. Foi registrada a posição de origem da artéria celíaca na aorta e sua esqueletopia em relação às vertebras. Também foi mensurada a distância entre as artérias celíaca e mesentérica cranial e verificada a correlação entre esta distância e o comprimento rostro-sacral dos espécimes, bem como a existência de diferenças nesta distância entre os sexos. Em 67% dos casos, a artéria celíaca foi o primeiro ramo visceral da aorta abdominal, emergindo caudalmente ao hiato aórtico. Em 33%, a artéria celíaca originou-se cranialmente ao hiato aórtico, caracterizando uma origem torácica. Apresentou uma distância média da artéria mesentérica cranial de 6,66 ± 1,85 mm, com valores mínimos e máximos de 4,63 e 10,83 mm respectivamente. Sua esqueletopia predominante foi ao nível da segunda vértebra lombar (L2), variando cranialmente até a primeira (L1). Houve correlação positiva moderada (r = 0,52) entre as distâncias das artérias celíaca e mesentérica cranial com o comprimento rostro-sacral dos indivíduos. Não houve diferença na distância entre as artérias quando comparados os sexos. O percentual elevado de indivíduos com origem da artéria celíaca cranialmente ao diafragma e a esqueletopia ao nível da segunda vértebra lombar foram as principais diferenças encontradas em relação aos carnívoros domésticos e pode ter implicação em medicina de animais silvestres.

The forelimb is the part of the post-cranial skeleton that provides more information about locomotion and life habits of a species. The objective of this study was to perform a detailed macroscopic, comparative, radiographic and osteometric investigation of the thoracic limb of Lycalopex gymnocercus. Twenty-four adult specimens collected dead from roadkill were studied. Analysis included macroscopic and comparative descriptions to other canids, radiographic images for recognition of trabeculation patterns and topographical arrangement of bones, linear and three-dimensional measurements, and histological evaluation of the clavicles. The forelimb skeleton of L. gymnocercus presented morphological and functional adaptations in every segment for a specialized cursorial locomotion and some ability to pronation and supination for capture of small vertebrates. There was a tendency for the bones to be longer in males, especially in the distal end of humerus, presumably to fixation of stronger antebrachial muscles. The vestigial clavicle bone was found in all the specimens, had a predominantly cartilaginous nature and was significantly larger in males. The basic conformation of the forelimb skeleton was similar to that of domestic and wild canids described in the literature, although peculiar characteristics of L. gymnocercus have been found.

Criollo horses are widely used in sports. Economic activities involving these animals generate more than 2.5 million dollars every year (ABCCC, 2017). There are several official sports modalities for Criollo horses, but they consist mainly of repetitive high-intensity movements.

Anatomical variation in wild canids is rarely described. Altered shapes, uni‐ or bilaterally situated, were observed in ventral laminae of C6 and/or in C7 vertebral body of two fox species: Lycalopex gymnocercus and Cerdocyon thous. The specimens were young adults, collected dead on highways in southern Brazil. Deformities were considered anatomical variations because apparently there was no interference in function. The occurrence of such variations in two related species from the same area can suggest an environmental common cause rather than genetic issues. Future studies may deepen the understanding between cause and effect of these vertebral deformities in wild canids.