Temporomandibular joint biomechanics and equine incisor occlusal plane maintenance.

In equine dentistry, the physiological incisor occlusal surface is visually perceived as a plane with a distinct inclination to the head's coronal plane, extending rostro-ventrally to caudo-dorsally. To better understand the formation of this inclined plane and its connection to dental wear, we investigated the hypothesis that it arises from masticatory movements and the considerable distance between mandibular articular heads and the incisor occlusal surfaces, acting as the three points of support for the mandibles. Leveraging data from a large-scale clinical study involving static and dynamic orthodontic measurements in horses, we approximated the mandibular movement range where incisor occlusion and dental wear occur. By introducing and testing a segment coordinate system, we explored possible angular deviations from the occlusal plane caused by mandibular roll and pitch rotations during two lateral mandibular movement patterns, protrusion and retrusion. Theoretical biomechanical calculations and simulations confirmed the visual perception of the incisor occlusal surface as a plane. To further examine our assumptions, we employed a simple mechanical simulator to assess incisor normal occlusion and provoked malocclusions (diagonal, smile, and frown bite) by modifying temporomandibular joint (TMJ) movement patterns. The results from clinical investigations were corroborated by both the theoretical analysis and mechanical simulations, strengthening our understanding of the biomechanical basis behind the physiological incisor occlusal plane maintenance in horses. These findings have significant implications for equine dental health and contribute to a thorough understanding of TMJ dynamics.

Extraskeletal myxoid chondrosarcoma: A study of 17 cases focusing on the diagnostic utility of INSM1 expression and presenting rare morphological variants associated with non-EWSR1::NR4A3 fusions.

Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain lineage. Insulinoma-associated protein 1 (INSM1) has recently been described as a highly specific and sensitive immunohistochemical marker for EMC. The goal of this study was to evaluate the diagnostic significance of INSM1 immunohistochemistry in EMC. Furthermore, correlations between molecular and morphological findings were performed. Sixteen of 17 EMC cases were stained with the INSM1 antibody. Tumors with at least 5% INSM1-positive cells and any staining intensity were considered positive. Molecular testing was successfully performed in 12/17 cases. The immunohistochemical analysis detected 13 INSM1-positive (81%) and 3 INSM1-negative tumors (19%). The extent of the staining was classified as 1+ in 7 cases (44%), 2+ in 2 cases (13%), 3+ in 2 cases (13%) and 4+ in 2 cases (13%). Intensity of immunostaining was weak in 5 cases (31%), moderate in 2 cases (13%) and strong in 6 cases (38%). Molecular assays revealed 8 EWSR1::NR4A3 positive tumors (67%), 2 TAF15::NR4A3 positive tumors (17%), 1 TCF12::NR4A3 positive tumor (8%) and 1 NR4A3 positive tumor (8%) in which no other gene alteration was identified. Two of them, namely TCF12 positive and one TAF15 positive tumors, were highly cellular and partially associated with pseudopapillary architecture. Our study found that moderate/strong expression of INSM1 in more than 25% of tumor cells was present in only 31% of cases. Thus, the diagnostic utility of INSM1 is rather low. Two morphologically unique cases of non-EWSR1 rearranged EMC with an extremely rare pseudopapillary growth pattern are also reported.

Unique expression patterns of the embryonal stem cell marker SOX2 and hormone receptors suggest the existence of a subpopulation of epithelial stem/progenitor cells in porcine and bovine endometrium.

BACKGROUND: There are currently insufficient data on the population of endometrial epithelial stem/progenitor cells in farm animals. OBJECTIVES: With the aim of identifying a potential population of epithelial stem/progenitor cells in the porcine and bovine endometrium, this study immunohistochemically examined the expression patterns of the oestrogen and progesterone receptors, as well as that of the embryonal stem cell marker SOX2. METHODS: A total of 24 endometrial tissue samples obtained from cycling pigs (n = 12) and cows (n = 12) were included in our study. Each endometrium was divided into basal, middle and luminal portions. The percentage of marker-positive cells and the intensity of the immunoreaction in each portion of the endometrium were determined. RESULTS: Inverse expression patterns of SOX2 and progesterone receptors were found in both animal species throughout the oestrous cycle. Strong diffuse SOX2 expression was detected in the basal portions of the glands, while a significant decrease in positivity and a weak immunoreaction were found in the luminal two thirds of the glandular epithelium. Strong progesterone receptor expression was observed in at least 90% of glandular cells in the middle and luminal portions, whereas weak staining and significant decrease in positivity were detected in the basal portions of the glands. One oestrogen receptor expression pattern resembled that of progesterone receptors. CONCLUSION: The inverse expression patterns of SOX2 and hormone (especially progesterone) receptors suggest that endometrial epithelial stem/progenitor cells represent a subset of cells that reside in the basal portions of the endometrial glands in both the bovine and porcine endometrium.

Safe corridors for external skeletal fixator pin placement in feline long bones.

OBJECTIVES: External skeletal fixation is an established technique in cats for biological fixation of long bone fractures, stabilisation of the joints, and treatment of shearing injuries and angular deformities. As appropriate and accurate pin insertion is imperative for a successful outcome, knowledge of topographic anatomy and areas that are safe (safe corridors) for pin placement is integral to successful surgery. At present, however, safe corridors have not been determined fully in feline orthopaedics, with surgeons having to rely on knowledge based on canine orthopaedics. This study was performed to determine safe corridors for pin placement in feline long bones. METHODS: The limbs of six feline cadavers were frozen. Only limbs with no history of orthopaedic conditions were used. Transverse sections through the limbs were examined, and anatomical structures were determined in relation to the bone. These structures were compared with those of the contralateral limbs, which were dissected for topographic assessment. Safe corridors were defined as topographic areas where no vital structures, muscles or joints were present. RESULTS: Examination of the humerus revealed safe corridors at its proximal craniolateral aspect and on the medial and lateral humeral condyles. Safe corridors of the antebrachium were identified on the lateral aspect of the olecranon, the distal two-thirds of the medial antebrachium and the distal third of the lateral antebrachium. Safe corridors in the femur consisted of a small area lateral to and just below the major trochanter, and on the medial and lateral femoral condyles. Evaluation of the tibia revealed safe corridors on the medial aspect of the entire tibia, the cranial aspect of the proximal tibia on the tibial crest and the area just proximal to the lateral malleolus. CONCLUSIONS AND RELEVANCE: Safe corridors for pin placement during external skeletal fixation in feline limbs differed from those in canine limbs. Knowledge of canine anatomy may be inapplicable to pin placement in feline limbs undergoing external skeletal fixation.

Histomorphology of the lower respiratory tract in the Indian crested porcupine (Hystrix indica).

The Indian crested porcupine (Hystrix indica) (ICP) is widely distributed in Asia; however, compared with other rodents, little is known about the structures of its respiratory system. The aim of this study was to evaluate the histomorphology of the lower respiratory portion of the ICP to provide a basis for the identification of the normal structure of this organ. The larynx, trachea and lungs of four carcasses of adult Indian crested porcupines (two males and two females) were dissected and fixed in 10% neutral-buffered formalin. The gross anatomy and histology of all specimens were evaluated. A macroscopic evaluation showed unique structures in the ICP respiratory system, including the presence of a chamber-like structure at the origin of the bronchi and a difference in epiglottis shape between males and females. Histologically, the stratified squamous epithelium covered the epiglottis and arytenoid cartilage, and the pseudostratified ciliated columnar epithelium covered the internal part of the thyroid and cricoid cartilages. Histomorphological studies showed a few goblet cells in the tracheal epithelium. In the bronchi and larger bronchioles, pseudostratified ciliated columnar epithelia were observed. Bronchi were surrounded by segments of cartilage. Distal bronchioles had a simple cuboidal/columnar epithelium with club (Clara) cells, lacked cartilaginous tissue in their walls and had a complete smooth muscle layer. These results revealed histomorphological differences between the ICP and other rodents.

An unusual case of infected uterus masculinus in a dog.

BACKGROUND: Paraprostatic cysts are large structures that develop between the prostate gland and urinary bladder, usually in older, intact dogs. Their incidence is reported to be 1.1-5.3% in dogs with prostatic disease. The aetiology of paraprostatic cysts is not fully understood, but they are believed to develop from the uterus masculinus. Whereas the uterus masculinus has been reported to communicate with the urethra in men and horses, no communication between the uterus masculinus and urethra has been identified in dogs. CASE PRESENTATION: An entire male dog was presented with a bloody discharge from its penis and tenesmus of 5 days' duration. A diagnosis of cystic uterus masculinus was made on the basis of the findings of abdominal ultrasonography and histopathology of tissues obtained during an exploratory laparotomy. In addition, a Sertoli cell tumour affecting both testes was diagnosed following scrotal castration. The cystic uterus masculinus was completely resected, after which the tenesmus and bloody discharge resolved. Thus, cystic uterus masculinus should be considered as a differential diagnosis for a paraprostatic cyst when such a lesion develops as part of the feminising effect of a Sertoli cell tumour. CONCLUSIONS: Cystic uterus masculinus should be considered as a differential diagnosis for tenesmus and penile discharge, and for structures resembling paraprostatic cysts. This case report confirms that a uterus masculinus can communicate with the urethra in dogs, as in other species, and demonstrates endocrine responsiveness, manifesting as epithelial and glandular metaplasia and mucus production, with the potential for subsequent infection.

Cranial cruciate ligament structure in relation to the tibial plateau slope and intercondylar notch width in dogs.

Cranial cruciate ligament (CCL) rupture is one of the most common orthopedic conditions in dogs. The pathogenesis of CCL rupture is not fully described and remains to be elucidated fully. Several hypotheses have been proposed to explain the etiology of these changes. The objective of this study was to investigate structural changes in the CCL in relation to the tibial plateau angle (TPA) and the intercondylar notch (ICN) width in dogs. Fifty-five skeletally mature dogs were included in this study. ICN width and TPA measurements were obtained from intact CCL stifles. Samples of the CCL, caudal cruciate ligament (CaCL), and femoral head ligament (FHL) were harvested and stained for routine histological and immunohistochemical analysis. Microscopic changes in the ligaments were observed and were found to correlate with the TPA and ICN width values. The degree of structural changes within the CCL was observed to correlate with an increasing TPA and a narrowing ICN width. Changes in the CCL are likely to be caused by excessive forces acting through the ligament in stifles with a high TPA. Chondroid metaplasia of the CCL is an adaptation to abnormal mechanics within the stifle joint caused by altered bone morphology.

Diagnostic imaging modalities and surgical anatomy of the temporomandibular joint in rabbits.

The temporomandibular joint (TMJ) is a condylar synovial joint that, together with the masticatory muscles, controls mandibular movement during mastication. The rabbit is often used as a model species for studying the mechanisms of TMJ diseases, and in regenerative research. However, there are significant differences between rabbit and human TMJs that should be taken into account before using this model for experimental research. Here, we use several analytical approaches (radiography, computed tomography and magnetic resonance imaging) to enable a detailed description and analysis of the rabbit TMJ morphology. Moreover, possible surgical approaches have been introduced with a focus on available access into the rabbit TMJ cavity, which relate our findings to clinical usage.

Conformation of the proximal tibia and cranial cruciate ligament disease in small breed dogs.

OBJECTIVES: To investigate the conformation of the proximal tibia in small breed dogs with and without cranial cruciate ligament disease (CCLD) and to identify morphologic abnormalities that may predispose to development of CCLD. METHODS: Mediolateral radiographs of the entire tibia of dogs <15 kg with surgically confirmed CCLD were retrospectively evaluated. Proximal tibial width (PTW), tibial plateau length (TPL), tibial plateau angle as described by Slocum and Slocum (sTPA), proximal tibial tuberosity angle (PTTA), tibial plateau angle as described by Inauen and colleagues (nTPA), and diaphyseal tibial width (DTW) were measured. The same variables were obtained from mediolateral radiographs of the entire tibia of dogs <15 kg without CCLD. In addition, a quotient nTPA/PTW, relative tibial tuberosity width (rTTW), and relative body weight (rBW) were calculated for each dog. Independent two-sample t-test (p = 0.05) was used to compare mean ± SD of all measured variables between the two groups. RESULTS: Gender, age, and weight mean ± SD were not significantly different between the two groups of dogs (p <0.05). Dogs with CCLD had significantly greater sTPA (p = 0.015) and rBW (p = 0.016). CLINICAL SIGNIFICANCE: In dogs of small breeds, a combination of an excessively steep tibial plateau and an increased relative body weight may predispose to early CCLD development. The slope of the tibial plateau was found to be caused by an abnormal caudal angulation of the proximal tibia, a phenomenon previously associated with CCLD development in small breed dogs in individual cases.

Facial pillars in dogs: an anatomical study.

This study describes the facial pillar system in dolichocephalic and brachycephalic breeds of dogs, and highlights its differences. Knowledge of facial pillar system anatomy is imperative to carry out successful fracture repair. The aim of our study was to describe the pillar system of the facial skeleton in dogs, and compare different shapes of dog skulls using native skulls, radiographs and computed tomography (CT). The heads of brachycephalic and dolichocephalic dogs were investigated following a maceration process using trans-illumination, radiography and CT. Ground sections were created from bones of the facial skeleton for investigation of osteon directions. This study has revealed that the facial skeleton of the dog has numerous sinuses supported by vertically and horizontally oriented bone pillars. These pillars can be divided into five principal regions in dolichocephalic skulls and six principal regions in brachycephalic skulls. Radiographic imaging of both the brachiocephalic and dolichocephalic skulls was not capable of discerning bone pillars. Computed tomography transverse and horizontal section images discerned all pillars observed in the illuminated skulls.

A porcine model: surgical anatomy of the orbit for maxillofacial surgery.

Due to its similarity to humans, the pig has proven to be a suitable biomodel for both research purposes and for training medical professionals, particularly in surgical specializations. For example, new implant materials have been tested on pig jaws and pigs have also been used in the development of new surgical techniques. For optimizing the effectiveness of such research or training, detailed data on the anatomy of their particular features are needed. At present, however, only limited information related to surgical and imaging anatomy of the facial and orbital areas of the pig and its comparison to human structures from the experimental surgery point of view is available in the literature. The aim of this study was to obtain such data and to compare the morphological structures of the porcine and human orbital regions and to lay down the foundation for practical use in experimental surgery. Ten pig heads were examined using computed tomography (CT) and magnetic resonance imaging (MRI) and, subsequently, a dissection of the orbit was carried out. Attention was focused on the structure of the orbit (floor, rim and nerves) frequently affected by pathological processes in humans (such as trauma, infection or tumours) and which consequently are frequently the subject of maxillofacial surgery. The porcine orbit is suitable for use in experimental medicine. However, if used in experiments, its anatomical peculiarities must be taken into consideration. Our study presents a foundation of basic knowledge for researchers who plan to use the pig as a biomedical model to investigate alternative treatments in the head region.

Morphometric assessment of periodontal tissues in relation to periodontal disease in dogs.

Dimensions of periodontal tissues are thought to predispose to the development of periodontal disease in man and dogs. Several studies have suggested that thin gingiva correlates with an increased incidence of periodontal disease. In this study, we hypothesized that the dimensions of periodontal tissues will vary in different breeds of dogs and could possibly correlate with the incidence of periodontal disease. Forty-two jaws of dogs aged up to 5-years were examined post-mortem and gingival and alveolar bone thickness were measured using methods of transgingival probing and digital calipers, respectively. Dogs were divided into three groups based on their body weight. Group I (< 5.0 kg; n=21), group II (5 to 10 kg; n=11), and group III (10 to 15 kg; n=10). Thickness of gingiva ranged from 0.30-mm to 3.2-mm and was relatively thinner in group I than in group II and III based on the means of ratios comparison. Alveolar bone thickness ranged from 0.27-mm to 4.1-mm and was relatively thinner in group I compared with groups II and III. Our study showed significantly thinner gingiva and alveolar bone in toy breed dogs compared with small and medium-sized breed dogs. Both gingival and alveolar bone dimensions may be predictors for severity of periodontal disease and influence clinical outcome in certain periodontal surgical procedures.

Gingival stippling in dogs: clinical and structural characteristics.

Diagnosis of periodontal disease, a frequent disorder in dogs, rests mainly upon the assessment of changes affecting the gingiva. Loss of gingival stippling, one of the early symptoms of periodontal disease in the human, could also indicate early periodontitis in the dog. The aim of this study was to determine the presence of gingival stippling in dogs, its location on alveolar processes, its association with age and inflammation, and its relation to the microstructure of the gingiva. The study concerns clinical, scanning electron and light microscopic examination of the gingiva of 48 dogs. Stippling, i.e. the granular appearance of the gingiva resembling irregularly distributed crater-like depressions of varying sizes, was present in adult but absent in young and senescent dogs. Stippling was most prominent at the level of the canine and the carnassial teeth. In contrast to the human gingiva, depressions and elevations of the stippled gingiva of the dog were not distributed uniformly. Presence of stippling indicates the presence of well developed mucosal layers and extensive interdigitation of epithelial rete pegs and papillary layer. Interaction of inelastic collagen fibres and a high hyaluronan content within papillary layer resulting in a high turgor of tissue due to the extensive water binding capacity of hyaluronic acid could also play a role in shaping of the gingival surface. The significance of gingival stippling in the diagnosis of periodontal disease in dogs is limited, as stippling occurs in healthy but also slightly inflamed attached gingiva of adult individuals.

Gingival thickness in dogs: association with age, gender, and dental arch location.

Reduced gingival thickness is one of many factors that might predispose humans to periodontal disease and subsequent gingival recession. Gingival thickness differs between individuals, and is associated with age, gender, and location on the dental arch. Different gingival phenotypes exist in the human population according to the thickness of gingiva. Similar information on gingival phenotypes in dogs is unknown. The aim of this study was to investigate the thickness of the gingiva in dogs and its relation to age, gender and location on the dental arch. For this study, 48 dogs of comparable size (40-cm at withers) were divided into three groups according to their age as follows: < 2-years of age; 2 to 8-years of age; > 8-years of age. Gingival thickness was measured in both the mandible and maxilla using a transgingival probing technique. The graded probe was inserted midway into the attached gingiva at the level of each tooth class region. Young and middle aged dogs had significantly thicker gingiva (1.67 +/- 0.17 mm and 1.68 +/- 0.18 mm, respectively) compared with older dogs (1.54 +/- 0.16 mm). There was no significant difference in gingival thickness based on location or gender Generally, the gingiva was thicker at the level of large teeth such as canine and carnassial teeth. Regions of thinner gingiva at the level of incisor and premolar teeth correlated with the regions of highest prevalence of periodontal disease found in previous studies.