Effect of skull morphology on fox snow diving.

Certain fox species plunge-dive into snow to catch prey (e.g., rodents), a hunting mechanism called mousing. Red and arctic foxes can dive into snow at speeds ranging between 2 and 4 m/s. Such mousing behavior is facilitated by a slim, narrow facial structure. Here, we investigate how foxes dive into snow efficiently by studying the role of skull morphology on impact forces it experiences. In this study, we reproduce the mousing behavior in the lab using three-dimensional (3D) printed fox skulls dropped into fresh snow to quantify the dynamic force of impact. Impact force into snow is modeled using hydrodynamic added mass during the initial impact phase. This approach is based on two key facts: the added mass effect in granular media at high Reynolds numbers and the characteristics of snow as a granular medium. Our results show that the curvature of the snout plays a critical role in determining the impact force, with an inverse relationship. A sharper skull leads to a lower average impact force, which allows foxes to dive head-first into the snow with minimal tissue damage.

Comparative studies on ovary and serum hormone levels in silver and blue foxes and their hybrids.

The silver and blue fox appear closely related despite their belonging to different genera, and the male and female fox hybrids are completely sterile in mating inter se or back to either of the parental groups. In the present study, we compared ovarian morphology and serum hormone concentrations among silver foxes, blue foxes, HSBs (silver fox male × blue fox female hybrids) and HBSs (blue fox male × silver fox female hybrids) during the pre-breeding and the breeding period. We found that either the fertile blue and silver foxes or the infertile hybrid foxes showed typical characteristics of ovary, with primordial, primary, secondary, antral and Graafian follicles. The diameters and quantities of different follicle classes in fertile foxes were greater than that in hybrids during the two period, while the thickness of zona pellucida (ZP) represented an opposite trend (P < 0.05). The relative weight of bilateral ovaries in fertile foxes was greater than that in hybrids during the pre-breeding period, while mean serum FSH represented an opposite trend during the breeding period (P < 0.05). The mean serum estradiol in fertile foxes was greater than that in HBS foxes during the pre-breeding period, and greater than hybrids during the breeding period (P < 0.05). These findings indicated that in the infertile hybrid foxes, lower estradiol levels produced by lesser and smaller antral follicles, thicker ZP during the two period, higher FSH levels during the breeding period, could be the basis of interpretations in cases of female fox hybrid infertility.

A three-dimensional reconstructive study of pelvic cavity in the red fox (Vulpes vulpes).

Three-dimensional (3D) reconstructive techniques are being used in many morphometric studies and clinical applications. The red fox is a wild animal localized in a wide geography. This study has been performed to determine morphometric properties of the pelvic cavity and reveal differences between sexes via 3D reconstruction obtained by multi-detector computed tomography images (MDCT) of the red fox. A total of 12 adult red foxes of both sexes were used in this study. Two-dimensional (2D) MDCT images of the pelvic cavity obtained and stored in DICOM format were used to reconstruct the 3D model. Mimics 13.1 program was used to perform the 3D reconstruction. A total of 24 dimensions were measured from the reconstructive model of the pelvic cavity. Twenty two dimensions were found to be significantly different (p < 0.05) between sexes. In conclusion, according to the pelvimetric data, it was determined that the red fox has sexual dimorphism and these data may be useful in wild animals morphological and gynaecological research. The authors hope to help in the diagnosis and treatment of the pelvic cavity-related orthopaedic and gynaecological disorders in the wild animals.

Geometric morphometric investigation of craniofacial morphological change in domesticated silver foxes.

To test the effects of domestication on craniofacial skeletal morphology, we used three-dimensional geometric morphometrics (GM) along with linear and endocranial measurements to compare selected (domesticated) and unselected foxes from the Russian Farm-Fox Experiment to wild foxes from the progenitor population from which the farmed foxes are derived. Contrary to previous findings, we find that domesticated and unselected foxes show minimal differences in craniofacial shape and size compared to the more substantial differences between the wild foxes and both populations of farmed foxes. GM analyses and linear measurements demonstrate that wild foxes differ from farmed foxes largely in terms of less cranial base flexion, relatively expanded cranial vaults, and increased endocranial volumes. These results challenge the assumption that the unselected population of foxes kept as part of the Russian Farm-Fox experiment are an appropriate proxy for 'wild' foxes in terms of craniofacial morphology and highlight the need to include wild populations in further studies of domestication syndrome to disentangle the phenotypic effects of multiple selection pressures. These findings also suggest that marked increases in docility cannot be reliably diagnosed from shape differences in craniofacial skeletal morphology.

Static allometry of a small-bodied omnivore: body size and limb scaling of an island fox and inferences for Homo floresiensis.

Island dwarfing is a paraphyletic adaptation across numerous mammalian genera. From mammoths to foxes, extreme body size reduction is shared by diverse organisms that migrate to an island environment. Because it largely occurs owing to ecological variables, not phylogenetic ones, skeletal characters in a dwarfed taxon compared with its ancestor may appear abnormal. As a result, allometric patterns between body size and morphological traits may differ for an island dwarf compared with its ancestor. The diminutive Late Pleistocene hominin, Homo floresiensis, displays a unique character suite that is outside of the normal range of variation for any extinct or extant hominin species. To better explain these as ecological traits due to island dwarfing, this research looks at how dwarfing on islands influences limb scaling and proportions in an organism in a similar ecological niche as H. floresiensis. Here, I analyze absolute limb lengths and static allometry of limb lengths regressed on predicted body mass of dwarfed island foxes and their nondwarfed relatives. Dwarfed island foxes have significantly smaller intercepts but steeper slopes of all limb elements regressed on predicted body mass than the mainland gray fox. These allometric alterations produce limbs in the island fox that are significantly shorter than predicted for a nondwarfed gray fox of similar body mass. In addition, the humerofemoral, intermembral, and brachial indices are significantly different. These results provide a novel model for understanding skeletal variation of island endemic forms. Unique body size and proportions of H. floresiensis are plausible as ecological adaptations and likely not examples of symplesiomorphies with Australopithecus sp. Caution should be exerted when comparing an island dwarf with a closely related species as deviations from allometric expectations may be common.

The vomeronasal organ of wild canids: the fox (Vulpes vulpes) as a model.

The vomeronasal system (VNS) has been extensively studied within specific animal families, such as Rodentia. However, the study of the VNS in other families, such as Canidae, has long been neglected. Among canids, the vomeronasal organ (VNO) has only been studied in detail in the dog, and no studies have examined the morphofunctional or immunohistochemical characteristics of the VNS in wild canids, which is surprising, given the well-known importance of chemical senses for the dog and fox and the likelihood that the VNS plays roles in the socio-reproductive physiology and behaviours of these species. In addition, characterising the fox VNS could contribute to a better understanding of the domestication process that occurred in the dog, as the fox would represent the first wild canid to be studied in depth. Therefore, the aim of this study was to analyze the morphological and immunohistochemical characteristics of the fox VNO. Tissue dissection and microdissection techniques were employed, followed by general and specific histological staining techniques, including with immunohistochemical and lectin-histochemical labelling strategies, using antibodies against olfactory marker protein (OMP), growth-associated protein 43 (GAP-43), calbindin (CB), calretinin (CR), α-tubulin, Gαo, and Gαi2 proteins, to highlight the specific features of the VNO in the fox. This study found significant differences in the VNS between the fox and the dog, particularly concerning the expression of Gαi2 and Gαo proteins, which were associated with the expression of the type 1 vomeronasal receptors (V1R) and type 2 vomeronasal receptors (V2R), respectively, in the vomeronasal epithelium. Both are immunopositive in foxes, as opposed to the dog, which only expresses Gαi2. This finding suggests that the fox possesses a well-developed VNO and supports the hypothesis that a profound transformation in the VNS is associated with domestication in the canid family. Furthermore, the unique features identified in the fox VNO confirm the necessity of studying the VNS system in different species to better comprehend specific phylogenetic aspects of the VNS.

[Computed tomography based elbow joint morphology and incidence of elbow dysplasia in the red fox (Vulpes vulpes)]. / Computertomografische Morphologie des Ellbogengelenks und Vorkommen der Ellbogengelenkdysplasie beim Rotfuchs (Vulpes vulpes).

OBJECTIVE: Elbow dysplasia (ED) is a common developmental disease of the canine elbow joint and one of the most frequent causes of forelimb lameness in domestic dogs (Canis lupus familiaris). ED is predominantly present in medium to large breed dogs, but has also been described in mixed breed dogs and smaller breeds. In the literature, no information is available concerning the existence of ED in wildlife species. The purpose of the present study was to obtain an overview of the elbow joint anatomy of the red fox as well as to demonstrate the incidence of ED in red foxes. Knowledge regarding the elbow conformation in red foxes may help to understand the effect of anatomical difference onto the pathogenesis of developmental elbow disease. MATERIAL AND METHODS: A total 94 elbow joints of 49 red foxes (Vulpes vulpes) were evaluated using computed tomography (CT) and were compared to canine elbow joints. RESULTS: Apart from size differences and minor species-specific variations, the anatomy of the elbow joints of red foxes and domestic dogs proved to be very similar. In the red foxes, the rounded conformation of the medial coronoid process was shown to be present in 76 % of the individuals. Two elbow joints in 2 red foxes exhibited pathological changes of the medial coronoid process in the CT imaging. CONCLUSION: The prevalence of medial coronoid disease in red foxes amounted to 2.1 % in the presented population. This observation is comparable to the prevalence of elbow dysplasia in small breed dogs. The rounded conformation of the medial coronoid process was found in more than three-quarters of the examined red foxes. This leads to the hypothesis that this conformation of the medial coronoid process could be the original, physiological variant. Selective breeding for such a morphological feature may be an approach to reduce the frequency of canine elbow dysplasia. CLINICAL RELEVANCE: The significance of anatomical characteristics in the development of elbow dysplasia is still unknown. Therefore, research concerning the pathogenesis of medial coronoid disease should set its focus not only on elbow joint anatomy, but also on other influencing factors, such as biomechanics, genetics and environmental parameters.

Skull morphology diverges between urban and rural populations of red foxes mirroring patterns of domestication and macroevolution.

Human activity is drastically altering the habitat use of natural populations. This has been documented as a driver of phenotypic divergence in a number of wild animal populations. Here, we show that urban and rural populations of red foxes (Vulpes vulpes) from London and surrounding boroughs are divergent in skull traits. These changes are primarily found to be involved with snout length, with urban individuals tending to have shorter and wider muzzles relative to rural individuals, smaller braincases and reduced sexual dimorphism. Changes were widespread and related to muscle attachment sites and thus are likely driven by differing biomechanical demands of feeding or cognition between habitats. Through extensive sampling of the genus Vulpes, we found no support for phylogenetic effects on skull morphology, but patterns of divergence found between urban and rural habitats in V. vulpes quantitatively aligned with macroevolutionary divergence between species. The patterns of skull divergence between urban and rural habitats matched the description of morphological changes that can occur during domestication. Specifically, urban populations of foxes show variation consistent with 'domestication syndrome'. Therefore, we suggest that occurrences of phenotypic divergence in relation to human activity, while interesting themselves, also have the potential to inform us of the conditions and mechanisms that could initiate domestication. Finally, this also suggests that patterns of domestication may be developmentally biased towards larger patterns of interspecific divergence.

Under the skin: Ixodes ticks in the subcutaneous tissue of red foxes (Vulpes vulpes) from Germany.

BACKGROUND: Ixodes spp. are vectors of zoonotic pathogens. All three active life stages (larvae, nymphs, adults) need to feed on a host in order to develop. Usually ticks parasitize attached to the external surface of their hosts' skin. Interestingly, in some cases ticks can also be found in the subcutaneous tissue in a variety of hosts, such as red foxes (Vulpes vulpes), raccoon dogs (Nyctereutes procyonoides) and dogs. METHODS: The visceral side of 126 red fox-furs from Germany was examined visually searching for ticks. The localization of ticks was recorded and assigned to ten specific body parts. Morphological identification of ticks was performed according to standardized taxonomic protocols. Ticks which could not be further identified were examined genetically via conventional PCR targeting the 16S rRNA and cox1 gene. Hematoxylin and eosin (H&E) staining was used for histopathological examination. RESULTS: In 111 out of 126 (88.1%) examined coats, at least one tick was found in the subcutaneous tissue. A total of 1203 ticks were removed from the subcutaneous tissue. Well-preserved ticks could be identified based on morphological criteria, but most ticks were in a progressed state of decomposition. Here, morphological species identification was not successful. Also, PCR methods did not lead to a successful species identification. The following species and development stages were found by morphological identification: Ixodes ricinus (female, n = 289; male, n = 8; nymph, n = 1), I. hexagonus (female, n = 2), I. canisuga (female, n = 1). Male I. ricinus were found individually or copulating in pairs with females. Subcutaneous ticks were localized at three predominant affected body parts: ears, axillar and inguinal region. Histological examination of subcutaneous ticks revealed a granulomatous panniculitis. CONCLUSIONS: To the authors' knowledge, this is the first finding of highly prevalent subcutaneous ticks in red foxes from Germany. Subcutaneous location of ticks seems to be very common in red foxes and the rule rather than the exception. Deep embedment of longirostra and long feeding times of females seem to put the subcutaneous location in favor. Most foxes were infested in the inguinal area, where the skin is thin and less hairy.

Computed tomography and cross-sectional anatomy of the head in the red fox (Vulpes vulpes).

The red fox (Vulpes vulpes) is a universally widespread wild carnivore in the world. It has an important impact on human interests and plays a vital role in conservation biology. There is no report to describe computed tomography (CT) of the red fox head and its correlation with gross anatomy. Therefore, the intent of the present study was to document, by CT, the basic anatomical structures in the head region of the red fox to lay the groundwork of an appropriate anatomical description of the head structures comparable with traditional dissection technique. Three red fox heads were imaged sagittally and transversely using CT scanner. Six red fox heads were then serially cut, sagittally and transversely, by an electric band saw, and the obtained slices were cleaned and photographed. Different anatomical structures on CT images and the corresponding anatomic sections were identified and labelled. CT images revealed an excellent three-dimensional definition of bony structures of the entire craniofacial region. Moreover, CT scans revealed different contrasts between bones, oral and nasal cavities, paranasal sinuses and pharynx which enabled good visualization of those structures. The paranasal sinus system in red fox was poorly developed and represented by a frontal sinus and a small sphenoid sinus, in addition to a maxillary recess. In conclusion, the series of CT images of the normal red fox head presented in the current study will serve as an anatomical reference for the normal head of the red fox, which in turn will improve knowledge for clinical interpretation.

Functional anatomy of the middle and inner ears of the red fox, in comparison to domestic dogs and cats.

Anatomical middle and inner ear parameters are often used to predict hearing sensitivities of mammalian species. Given that ear morphology is substantially affected both by phylogeny and body size, it is interesting to consider whether the relatively small anatomical differences expected in related species of similar size have a noticeable impact on hearing. We present a detailed anatomical description of the middle and inner ears of the red fox Vulpes vulpes, a widespread, wild carnivore for which a behavioural audiogram is available. We compare fox ears to those of the well-studied and similarly sized domestic dog and cat, taking data for dogs and cats from the literature as well as providing new measurements of basilar membrane (BM) length and hair cell numbers and densities in these animals. Our results show that the middle ear of the red fox is very similar to that of dogs. The most obvious difference from that of the cat is the lack of a fully formed bony septum in the bulla tympanica of the fox. The cochlear structures of the fox, however, are very like those of the cat, whereas dogs have a broader BM in the basal cochlea. We further report that the mass of the middle ear ossicles and the bulla volume increase with age in foxes. Overall, the ear structures of foxes, dogs and cats are anatomically very similar, and their behavioural audiograms overlap. However, the results of several published models and correlations that use middle and inner ear measurements to predict aspects of hearing were not always found to match well with audiogram data, especially when it came to the sharper tuning in the fox audiogram. This highlights that, although there is evidently a broad correspondence between structure and function, it is not always possible to draw direct links when considering more subtle differences between related species.

Ophthalmic contributions to assessing eyes of two neotropical canids: Cerdocyon thous and Chrysocyon brachyurus.

OBJECTIVE: To describe selected ophthalmic tests and anatomical features of eyes of crab-eating foxes (Cerdocyon thous) and maned wolves (Chrysocyon brachyurus). ANIMALS STUDIED: Six crab-eating foxes (12 eyes), eight maned wolves (16 eyes). PROCEDURES: Intramuscular and/or inhalatory anesthesia, ophthalmic evaluation with portable slit-lamp biomicroscope, Schirmer tear test (STT), intraocular pressure measurement with rebound and applanation (crab-eating fox only) tonometers, measurement of palpebral fissure length (PFL), gonioscopy, and fundoscopy. Data were analyzed with ANOVA and Tukey's tests. RESULTS: Both species presented upper and lower eyelids, both with eyelashes and Meibomian glands openings. A third eyelid was also present. In partial miosis, pigmented projections were observed along the edge of the pupil. The draining angle was open, with thin pectinate ligaments. The retina was holangiotic. For crab-eating foxes, mean ± standard deviation values were as follows: STT: 4.33 ± 2.96 mm/min; PFL: 17.45 ± 1.55 mm; rebound tonometry: 10.70 ± 3.43 mm Hg (TonoVet® calibration D),5.66 ± 3.44 mm Hg (TonoVet® calibration P), 17.00 ± 4.64 mm Hg (TonoVet® Plus calibration dog); and applanation tonometry: 11.70 ± 5.70 mm Hg(TonoPen® XL). For maned wolves, the mean ± standard deviation values were as follows: STT: 9.31 ± 7.40 mm/min; PFL: 22.79 ± 1.63 mm; rebound tonometry: 11.00 ± 2.77 mm Hg (TonoVet® calibration D), 6.78 ± 2.58 mm Hg (TonoVet® calibration P), and 18.29 ± 3.47 mm Hg(TonoVet® Plus calibration dog). CONCLUSIONS: This study contributes with knowledge that can help the clinical assessment regarding eyes of crab-eating foxes and maned wolves. The data herein presented for rebound tonometry are new for both species.

The amygdala of the common shrew, guinea pig, rabbit, fox and pig: five flavours of the mammalian amygdala as a consequence of clade-specific mosaic-like evolution.

The amygdala is a part of neural networks that contribute to the regulation of emotional behaviours and emotional learning, stress response, and olfactory, pheromonal and reproductive functions. All these various functions are processed by the three main functional systems, frontotemporal, autonomic and olfactory, which are derived from different telencephalic sources (claustrum, striatum and olfactory cortex) and are represented, respectively, by the basolateral complex (BLC), the central complex (CC) and corticomedial complex (CMC) of the amygdala. The question arises of how these three functional systems evolved during mammalian phylogeny to fit the amygdala to specific needs of various animals. In the present study, we provide quantitative information regarding the individual volumes and neuron numbers in the BLC, CC and CMC of the common shrew, guinea pig, rabbit, fox and pig, a series of animals arranged according to increasing size and complexity of the brain. The results show that, in this series of animals, the BLC underwent a gradual size increase in volume and number of neurons, whereas the CMC was gradually reduced with regard to both these measures. The CC was more or less conserved across studied species. For example, the volume of the amygdala in pigs is ~250 times larger than that in shrews and it also has almost 26 times as many neurons as the amygdala of shrews. However, the volumes of the BLC, CC and CMC were ~380, 208 and 148 times larger, respectively, in pigs than in shrews. The number of neurons in these three regions was ~38, 23 and 20 times greater, respectively, in pigs than in shrews. The results also show striking morphometric similarities of the amygdala in the guinea pig and rabbit as well as fox and pig. For example, the percentages of neurons in the fox and pig are 42.23% and 42.78%, respectively, for the BLC, 16.64% and 16.58%, respectively, for the CC, and 41.12% and 40.64%, respectively, for the CMC. In conclusion, our results indicate that the amygdala does not evolve as a single unit but, instead, the three main functional systems evolved independently, which suggests that brain structures with major functional links evolve together independently of evolutionary changes in other unrelated structures. The size progression of the BLC parallels the size progression of the neocortex with which it is strongly functionally linked, whereas the CMC is strongly connected to olfactory regions, and all these structures follow the same regression course. Remarkable morphometric similarity of the amygdala in the guinea pig and rabbit as well as in the fox and pig, however, suggest that there must also be another mechanism shaping the morphology of the amygdala and the brain during evolution. The gradual nature of size changes in the BLC and CMC support this hypothesis as well.

Morphometry of mental foramina applied to local anesthesia in hoary fox (Lycalopex vetulus Lund, 1842) / Morfometría de forámenes mentales aplicada a la anestesia local en zorro de campo común (Lycalopex vetulus Lund, 1842)

In order to perform local anaesthetic blockade of the mental nerves, it is fundamentally to determine anatomical references, including the precise identification of the mental foramina; however, the literature does not present specific data on such structures in the Hoary Fox. Therefore, the objective was describing the morphometry of the mental foramina of this specie, in order to correlate its topographies with the mandibular anatomical reference points, supporting the effective technique for mental desensitization. For this purpose, four mandibles of adult bodies of Lycalopex vetulus were used. Bilaterally, three mental foramina were observed located on the rostral third of the lateral margin of the mandibular body. One of them is more caudal, positioned ventrally to the lower third premolar tooth; a medium one, is located ventrally to the lower first premolar tooth; and a rostral one, placed ventrally to the lower intermediate incisor tooth. There were no statistically significant differences between the antimeres. Therefore, it is indicated that the local anaesthetic block of the mental nerves in this species should be performed by inserting the needle approximately 4.4 mm in a ventrodorsal direction. It is necessary positioning it perpendicularly to the ventral margin of the mandibular body and juxtaposed to its lateral face, using as anatomical reference the interalveolar space located between the first two lower premolar teeth. Thus, that the point established for anaesthetic injection (caudal limit of the ventral margin of the middle mental foramen), provides greater safety for its realization since, for small animals, the recommendation for blockade is represented by needle penetration on the direction of emergence of the mental nerve and artery from this foramen, which makes these structures more exposed to iatrogenic lesions resulting from the technique.

Para realizar el bloqueo anestésico local de los nervios mentales, es fundamental determinar referencias anatómicas, incluida la identificación precisa de los forámenes mentales; sin embargo, la literatura no presenta datos específicos referente a estas estructuras en el zorro de campo común. Por lo tanto, el objetivo fue describir la morfometría de los forámenes mentales de esta especie, para correlacionar sus topografías con los puntos de referencia anatómicos mandibulares, apoyando la técnica efectiva para la desensibilización mental. Para este propósito, se utilizaron cuatro mandíbulas de Lycalopex vetulus adultos. Bilateralmente, se observaron tres resistencias mentales ubicadas en el tercio rostral del margen lateral del cuerpo mandibular. Uno de ellos es más caudal, posicionado ventralmente hacia el tercer diente premolar inferior; uno mediano, localizado ventralmente hacia el primer diente premolar inferior; y uno rostral, colocado ventralmente al diente incisivo intermedio inferior. No se observaron diferencias estadísticamente significativas entre los antímeros. Por lo tanto, el bloqueo anestésico local de los nervios mentales en esta especie debe realizarse insertando la aguja aproximadamente 4,4 mm en dirección ventrodorsal. Es necesario colocar ésta perpendicularmente al margen ventral del cuerpo mandibular y yuxtapuesto a su cara lateral, utilizando como referencia anatómica, el espacio interalveolar ubicado entre los dos primeros dientes premolares inferiores. De este modo, el punto establecido para la inyección de anestesia (límite caudal del margen ventral del foramen mental medio), proporciona una mayor seguridad para su realización ya que, para los animales pequeños, la recomendación de bloqueo está representada por la penetración de la aguja en la dirección de emergencia del nervio mental y la arteria de este foramen, lo que hace que estas estructuras estén más expuestas a las lesiones iatrogénicas resultantes de la técnica.

Morphometry of the mandibular foramen applied to local anesthesia in hoary fox (Lycalopex vetulus) / Morfometria do forame mandibular aplicada à anestesia local em raposa-do-campo (Lycalopex vetulus)

Great part of the veterinary care in wild carnivores is intended to treat the dental disorders, and oral cavity disorders may generally affect the animal health as a whole. It is factual that knowing the location of the mandibular foramen is vital for local anesthetic block of the inferior alveolar nerve, however, there is still no data on the morphometry of the hoary fox mandibular foramen. The aim was describing morphometry of the mandibular foramen of this species and associating its position with anatomic reference points in the mandible, thus providing support for more effective local anesthetic block of the inferior alveolar nerve in such species. Four adult jaws of Lycalopex vetulus were used. Radiography and biometrics of the hemimandibulas were performed. The rostral third of the jaw body in a lateral view presented three mental foramens, being a rostral, a medium and a caudal. Each hemimandibula presented I3/C1/PM4/M3. The angle of the mandible was marked by the masseteric fossa, the angular incisure, the angular process and the mandibular foramen, and this last one located perpendicularly to the dorsal edge of the angular incisures in medial view. In this view, the crevice to the milohyoid nerve, projected in the caudodorso rostral direction, was also evidenced. The ramus of the mandible was characterized by the presence of the condylar and coronoid processes, and by the dorsal and ventral mandibular incisions. Statistical analyzes did not present significant differences between the antimeres of the studied animals, and the penetration of the needle perpendicularly to the dorsal end of the angular incision on average 8.79mm, overlapped to the medial face of the angle of the mandible could be indicated. Alternatively, the access may also be achieved by inserting the needle in an average of 17.69mm perpendicular to the dorsal end of the angular process, in contact with the medial aspect of the angle of the mandible, and in caudo-rostral projection, also allowing a better anesthetic blockade of the inferior alveolar nerve in L. vetulus. It can also be concluded that the masseteric fossa, the dorsal and ventral mandibular angles, the crevice to the milohyoid nerve, the ramus of the mandible and the mandibular foramen presented differences in their topographic descriptions when compared to the other canids.(AU)

A maior parte dos atendimentos veterinários em carnívoros silvestres destina-se ao tratamento das afecções dentárias, sendo que doenças de cavidade oral podem afetar a saúde do animal como um todo. É factível que o conhecimento da localização do forame mandibular é essencial para o bloqueio anestésico local do nervo alveolar inferior, entretanto, ainda são inexistentes dados sobre a morfometria do forame mandibular de raposa-do-campo. Objetivou-se descrever a morfometria do forame mandibular desta espécie, e correlacionar sua posição com pontos de referência anatômica na mandíbula, oferecendo subsídio para um bloqueio anestésico local mais efetivo do nervo alveolar inferior nesta espécie. Foram utilizadas quatro mandíbulas de cadáveres adultos de Lycalopex vetulus. Realizou-se a radiografia e as biometrias das hemimandíbulas. O terço rostral do corpo da mandíbula em uma vista lateral apresentou três forames mentuais, sendo um rostral, um médio e um caudal. Cada hemimandíbula apresentou I3/C1/PM4/M3. O ângulo da mandíbula foi marcado pela fossa massetérica, pela incisura angular, pelo processo angular e pelo forame mandibular, e este último localizado perpendicularmente ao extremo dorsal da incisura angular em vista medial. Nesta vista, também se evidenciou o sulco para o nervo milohióideo, projetado em sentido caudodorsorostral. O ramo da mandíbula foi caracterizado pela presença dos processos condilar e coronóide, e pelas incisuras mandibulares dorsal e ventral. As análises estatísticas não apresentaram diferenças significantes entre os antímeros dos animais estudados, podendo-se indicar a penetração da agulha perpendicularmente ao extremo dorsal da incisura angular em média 8,79mm, justaposto à face medial do ângulo da mandíbula. Alternativamente, o acesso também poderá ser realizado introduzindo a agulha em média 17,69mm de forma perpendicular ao extremo dorsal do processo angular, em contato com a face medial do ângulo da mandíbula, e em projeção caudorostral, permitindo também um melhor bloqueio anestésico do nervo alveolar inferior na L. vetulus. Também se pode concluir que a fossa massetérica, as incisuras angular, mandibulares dorsal e ventral, o sulco para o nervo milohióideo, o ramo da mandíbula e o forame mandibular apresentaram diferenças em suas descrições topográficas quando comparados aos demais canídeos.(AU)

Comparative studies on testis, epididymis and serum hormone concentrations in foxes, and hybrids during the pre-breeding period.

Silver fox and blue fox belong to different genera, and the hybrid males are reproductively sterile. In the present study, there was a comparison of testicular and epididymal morphology and serum hormone concentrations among silver foxes, blue foxes, and the hybrids during the pre-breeding period, using 20 male silver foxes, 20 male blue foxes, 15 male HSBs (silver fox male × blue fox female hybrids) and 15 male HBSs (blue fox male × silver fox female hybrids), respectively. Hybrids had a smaller diameter of seminiferous tubules than pure-species males, and testes of hybrid males did not differ in mean size and relative weight from pure-species males. There were many Sertoli cells and spermatogenic cells in silver foxes and blue foxes, while numbers of spermatogonia and primary spermatocytes were less with no secondary spermatocytes in the hybrids. Furthermore, mean serum testosterone and estradiol concentrations in the hybrids were less, and FSH, LH, and PRL were greater than that in silver foxes and blue foxes (P < 0.05), suggesting that lesser concentrations of testosterone and estradiol and greater concentrations of FSH, LH and prolactin can inhibit the completion of spermatogenesis during the pre-breeding period. The results indicate that fox hybrid sterility may result from failures at the early stages of spermatogenesis.

Mandibular shape in farmed Arctic foxes (Vulpes lagopus) exposed to persistent organic pollutants.

We investigated if dietary exposure to persistent organic pollutants (POPs) affect mandibular asymmetry and periodontal disease in paired male-siblings of Arctic foxes (Vulpes lagopus). During ontogeny, one group of siblings was exposed to the complexed POP mixture in naturally contaminated minke whale (Balaenoptere acutorostarta) blubber (n = 10), while another group was given wet feed based on pig (Sus scrofa) fat as a control (n = 11). The ∑POP concentrations were 802 ng/g ww in the whale-based feed compared to 24 ng/g ww in the control diet. We conducted a two-dimensional geometric morphometric (GM) analysis of mandibular shape and asymmetry in the foxes and compared the two groups. The analyses showed that directional asymmetry was higher than fluctuating asymmetry in both groups and that mandibular shape differed significantly between the exposed and control group based on discriminant function analysis (T2 = 58.52, p = 0.04, 1000 permutations). We also found a non-significantly higher incidence of periodontal disease (two-way ANOVA: p = 0.43) and greater severity of sub-canine alveolar bone deterioration similar to periodontitis (two-way ANOVA: p = 0.3) in the POP-exposed group. Based on these results, it is possible that dietary exposure to a complexed POP mixture lead to changes in jaw morphology in Arctic foxes. This study suggests that extrinsic factors, such as dietary exposure to POPs, may affect mandibular shape and health in a way that could be harmful to wild Arctic populations. Therefore, further studies using GM analysis as an alternative to traditional morphometric methods should be conducted for wild Arctic fox populations exposed to environmental contaminants.

Anatomical variations of the caudomedial antebrachial muscles in the crab-eating fox (Cerdocyon thous) / Variaciones anatómicas de los músculos caudo-mediales del antebrazo del zorro perruno (Cerdocyon thous)

The crab-eating fox (Cerdocyon thous) is a wild canid distributed in South America, which is susceptible to traumas caused by captors, accidents on roads, and traps. Due to these events their thoracic limbs can be involved at the level of the forearm, therefore, knowledge of the gross anatomy of its muscles is important in order to develop clinical and surgical procedures at this level compared with the domestic dog. The main objective of this investigation was report the intra and interspecific anatomical variations of the caudomedial forearm muscles in Cerdocyon thous in comparison mainly with the domestic dog. Six dead specimens from wildlife care centres of CORPOCALDAS were used. These were fixed with a solution of formaldehyde, mineral oil and phenic acid. Both thoracic limbs of each specimen were dissected from superficial to deep, emphasizing the caudomedial part of the forearm in order to review the anatomical characteristics of each muscle. These muscles were similar to those reported in the domestic dog, but some variations were observed such as the innervation of the pronator teres muscle by the musculocutaneous nerve in a specimen unilaterally; the formation of an accessory muscle from the ulnar head of the flexor carpi ulnaris muscle in most specimens; and the vestigial presence of the anconeus epitrochlearis muscle in a specimen bilaterally.

El zorro perruno (Cerdocyon thous) es un cánido silvestre distribuido en Sudamérica, el cual es susceptible a traumas causados por captores, accidentes en carreteras y trampas, donde pueden verse involucrados sus miembros torácicos a nivel del antebrazo, por lo tanto, conocer la anatomía de sus músculos es importante, ya que ésta servirá como base en la realización de procedimientos clínicos y quirúrgicos a este nivel en comparación con el perro doméstico. El objetivo principal de esta investigación fue reportar las variaciones anatómicas intra e interespecíficas de los músculos caudo-mediales del antebrazo de C. thous en comparación principalmente con el perro doméstico. Se utilizaron seis especímenes muertos bajo la jurisdicción de CORPOCALDAS. Estos se fijaron con una solución en mezcla de formaldehído, aceite mineral y ácido fénico. Se diseccionaron de superficial a profundo los dos miembros torácicos de cada espécimen, haciendo énfasis en la parte caudo-medial del antebrazo para revisar las características anatómicas de cada músculo, las cuales fueron similares a las reportadas al perro doméstico, pero se observó en un espécimen de manera unilateral la inervación al músculo pronador teres por parte del nervio musculocutáneo; en la mayoría de especímenes se observó la formación de un músculo accesorio a partir de la cabeza ulnar del músculo flexor ulnar del carpo; y en un espécimen la presencia vestigial del músculo ancóneoepitroclear.

Anatomy of the abdominal aorta in the hoary fox (Lycalopex vetulus,Lund, 1842) / Anatomia da aorta abdominal em raposa-do-campo (Lycalopex vetulus, Lund, 1842)

The hoary fox (Lycalopex vetulus,Lund, 1842) is the smallest Brazilian canid, whose weight varies between 2 and 4 kg, has a slender body, a small head, and a short and blackened snout. Despite being considered an endemic species, little is known about the hoary fox as it is one of the seven less studied canids in the world. Thus, this study aimed to describe the anatomy of the abdominal aorta artery of the hoary fox and to compare it with the pre-established literature data in domestic canids. For this purpose, we used two adult hoary foxes without definite age. We collected the corpses of these animals along roadsides of Catalão-GO, being later fixed and conserved in a 10% formalin solution. The results showed that the abdominal aorta in hoary fox is at the ventral face of the lumbar region vertebral bodies, being slightly displaced to the left of the median plane. The first branch is visceral, named celiac artery, followed by a paired parietal branch: the phrenic abdominal arteries. The third and fourth branches are the cranial mesenteric arteries and the right and left are the renal arteries, respectively. The posterior branches of the renal arteries are equally visceral, paired, being called testicular arteries. Distal to the latter, both the caudal mesenteric artery and deep circumflex iliac arteries originate. Finally, two large external iliac arteries and its terminal branches composed of internal iliac arteries and the median sacral artery originate. In addition, five pairs of lumbar arteries originate alongside the abdominal segment of the aorta. Considering these findings, it is possible to conclude that despite the hoary fox being a wild animal, the anatomy of its abdominal aorta is very similar to that of domestic canids.(AU)

A raposa-do-campo (Lycalopex vetulus,Lund, 1842) é o menor canídeo brasileiro, cujo peso varia entre 2 e 4 quilos, possui corpo esguio, a cabeça é pequena, focinho curto e enegrecido. Considerada uma espécie endêmica, pouco se sabe a seu respeito, e é um dos sete canídeos menos estudados no mundo. Assim, o presente estudo teve o objetivo de descrever a anatomia da parte abdominal da artéria aorta em raposa-do-campo e comparar com dados literários pré-estabelecidos de canídeos domésticos. Para a realização deste estudo foram utilizados dois exemplares de raposa-do-campo, adultos, sem idade definida. Os cadáveres dos animais foram recolhidos às margens de rodovias no entorno da Catalão-Goiás, fixados em solução aquosa de formol a 10% e conservados na mesma solução. Os resultados mostraram que a aorta abdominal da raposa-do-campo está localizada sobre a face ventral dos corpos vertebrais da região lombar, levemente deslocada para a esquerda do plano mediano. O primeiro ramo é visceral, denominado artéria celíaca, seguido por um ramo parietal, pareado, as artérias frênico-abdominais. O terceiro e quarto ramos são a artéria mesentérica caudal e as artérias renais direita e esquerda, respectivamente. Os ramos posteriores das artérias renais são igualmente viscerais, pareados, denominados artérias testiculares. Distal à essas últimas, originam-se a artéria mesentérica caudal e as artérias circunflexas ilíacas profundas. Finalmente surgem duas grandes artérias ilíacas externas e os ramos terminais compostos pelas artérias ilíacas internas e artéria sacral mediana. Ao longo do trajeto da aorta abdominal, cinco pares de artérias lombares se originam da face dorsal. Considerando esses achados, pode ser concluído que a anatomia da aorta abdominal da raposa-do-campo é muito similar àquela de canídeos domésticos, embora ela seja um animal silvestre. (AU)

Functional myology of the thoracic limb in Pampas fox (Lycalopex gymnocercus): a descriptive and comparative analysis.

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.