BACKGROUND:Pulmonary vein (PV) myocardial sleeves (MSs) harbour an arrhythmogenic substrate for atrial fibrillation. However, equine-specific data on MS distribution and wall thickness are limited yet essential for developing ablation strategies. In humans, posterior interatrial connections can compromise right-sided PV isolation. OBJECTIVES:To study equine PV MS distribution, quantify ostial/branch diameters, antral lengths, characterise MS distal edge morphology, measure wall thickness and explore an interatrial myocardial continuity between the MSs of caudal branches draining through ostium III (PV III) and caudal vena cava (CaVC). STUDY DESIGN:Post-mortem, cross-sectional. METHODS:Twenty-three Warmblood hearts underwent left atrial and PV dissection. All four ostia (I-IV) were opened. From calibrated photographs, ostial and branch diameters, antral length, MS length and coverage, distal edge morphology (sharp/blurred), and myocardial thickness were assessed at standardised locations. In 6/23 hearts, a 3 × 1 cm dorsal interatrial septum (IAS) sample including PV III, and CaVC MSs was stained with Masson's trichrome and examined for myocardial continuity. RESULTS:Four principal ostia were present in 20/23 hearts and 5 in 3/23, with variable accessory vein openings. Ostia II and III were largest, I smallest. PV III showed full antral MS coverage with branch extensions, whereas MSs in other PVs were often confined to the antrum. Distal MS edges were often blurred at PV III. The MS thickness was largest at ostia II and III and smallest at ostium I. Histology showed that the dorsal interatrial myocardium was continuous with the PV III and CaVC MSs. MAIN LIMITATIONS:Postmortem study, Warmblood cohort, few samples, no electrophysiology. CONCLUSIONS:Equine PV MS anatomy is ostium-specific in extent, distal edge, and thickness. These data provide anatomical information relevant to ablation planning and to future catheter design. Morphological evidence suggests a dorsal interatrial myocardial continuity through the IAS that warrants electro-anatomical confirmation.

Understanding the anatomy of the paranasal sinuses and nasal cavity in alpacas (Vicugna pacos) is limited by scarce published data. This prospective cadaveric study aimed to enhance the interpretation of clinical cross-sectional imaging and expand knowledge of normal anatomy using computed tomography (CT), magnetic resonance imaging (MRI), macroscopic cross-sections, and 3D reconstructions (Amira v5.3.3; Thermo Fisher Scientific, Waltham, MA, USA). Seven alpacas (median age 3.9 years; five males, two females) underwent CT and MRI. Frozen anatomical slices were obtained from three heads, and sinus fenestration from one. All specimens had a conchal (dorsal and middle), maxillary, frontal, and ethmoidal sinus. The 6/7 specimens presented a sphenoidal sinus, and 5/7 specimens presented bilateral lacrimal sinuses. Notably, the ventral conchal and palatine sinuses were absent in all specimens. The frontal sinus was divided into a smaller, non-concamerated, medial compartment and a large, diversely concamerated, lateral compartment in all specimens, except one in which only a common frontal sinus was present. The sphenoidal sinus was divided by a variably thickened septum in 3/6 heads. The ethmoidal bone contained air-filled cells divided into lateral and medial groups. The lateral cells presented a lengthier rostro-caudal extension and connected to the frontal, lacrimal, and maxillary sinuses, whereas the medial cells were shorter and surrounded the middle conchal sinus.

The TIE2 transmembrane receptor protein, known for its role in vascular stability and blood vessel remodeling, has primarily been studied in endothelial cells. This receptor has also been found on several non-endothelial cell types including podocytes, although its presence on podocytes remains a matter of debate. Conventional immunofluorescence approaches applied to membrane proteins are often challenged by the strong tissue autofluorescence spanning green and red parts of the electromagnetic spectrum, sample thickness, and the antibody specificity. Here, we used stimulated emission depletion (STED) microscopy, a super-resolution microscopy method, to detect the TIE2 protein in complex biological tissue with a resolution of less than 50 nm. To further confirm the presence of TIE2 on podocytes and to investigate its localization, we used fluorescence lifetime imaging microscopy (FLIM) to more effectively distinguish between nonspecific autofluorescence and specific emission in cleared and antibody-labeled tissue samples. By correlating these two techniques, we mapped the subcellular localization of TIE2 on mouse podocytes and confirmed its presence on the cell surface facing the Bowman's space, albeit at lower expression levels. This study highlights the potential complementary power of STED and FLIM methods and provides additional evidence that the TIE2 receptor is present on podocytes.

Galsome-NEO is a glycolipid-adjuvanted mRNA lipid nanoparticle (LNP) cancer vaccine encoding neo-epitopes for evaluation in a phase 1 study in patients with non-small cell lung cancer. To assess the safety of Galsome-NEO, a repeated-dose toxicity study was conducted in Wistar Han rats involving three intramuscular doses of 30 μg mRNA. A dose-escalation study in piglets tested three doses of 3, 15, and 100 μg mRNA. Rats showed a pronounced pro-inflammatory response, evidenced by cytokine secretion and an acute phase reaction. Clinical findings included temporary local reactions (maximum grade 3), elevated temperatures, and weight loss. In pigs, all doses were well tolerated. Blood analysis showed elevated alkaline phosphatase and decreased thrombocytes in rats, while pigs had reduced reticulocyte counts. Histology revealed hepatocyte vacuolation in rats and immune infiltration at injection sites in both species. In rats, blood and histology alterations resolved 3 weeks post dosing, except for immune infiltration in the connective tissue at injection sites in two females. Galsomes with mRNA encoding the Chlamydia trachomatis major outer membrane protein induced T cell responses in pigs. Natural killer T cell activation was observed in both species. These findings align with the safety data for the COVID-19 mRNA vaccine, Comirnaty, and demonstrate Galsomes’ potential in large animals.

The interatrial septum morphology, shaped by the septum primum and secundum fusion, results in the formation of the fossa ovalis (FO) and its limbus. Incomplete fusion can lead to a patent foramen ovale (PFO), while complete fusion may produce septal ridges and pouches (SPs), with SPs in humans linked to ischemic stroke and atrial arrhythmias. In horses, atrial tachycardia and fibrillation often originate near the FO. This study examines adult equine interatrial septum morphology to enhance understanding the region and guide electrophysiological interventions for equine cardiac arrhythmias. Post-mortem examinations of 62 adult equine hearts, assessed the interatrial septum morphology from both right and left sides, measuring the dimensions of the FO and the craniocaudal length, and dorsoventral height of the SPs. Histological analysis at selected septal locations evaluated the wall's thickness and composition. Significant morphological variations were observed, particularly the consistent presence of right-sided SP. The septum wall comprises three layers, with the central layer containing cardiomyocytes in varied orientations, interspersed with fibroadipose tissue, features potentially contributing to atrial arrhythmias. Understanding the equine interatrial septum morphology is important for optimizing transseptal puncture outcomes, by facilitating accurate intracardiac echocardiography interpretation, guiding precise puncture site selection and improving procedural safety and efficacy.

INTRODUCTION/OBJECTIVES:The coronary sinus (CS) and great cardiac vein (GCV) are crucial in cardiac electrophysiology. In horses, CS/GCV catheterisation is increasingly performed for arrhythmia diagnosis and treatment. Improved anatomical understanding is needed to clarify relationships to surrounding structures. ANIMALS, MATERIALS AND METHODS:Postmortem examination of 64 adult warmblood equine hearts was performed. Middle cardiac vein and vein of Marshall ostia locations were described. Right atrial myocardial sleeve (MS) length was measured from the CS ostium. In 23 horses, CS/GCV length in the coronary groove and distance to left atrial myocardium (LAm), left ventricular myocardium and mitral annulus were measured at eight levels. The MS-atrial myocardium relationship was assessed histologically. RESULTS:The middle cardiac vein opened more frequently into the right atrium than CS, with the vein of Marshall consistently near the Vieussens valve. Mean (standard deviation) CS length was 28 (13) mm. Right atrial MS extended 52 (18) mm into the GCV (63/64 horses). Mean CS/GCV length was 240 (36) mm in the coronary groove. The GCV-LAm distance changed from median [interquartile range] of 10 [6] mm (CS end) to 2 [2] mm (mid-left free wall) to 32 [13] mm (paraconal interventricular sulcus) with opposite left ventricular myocardium relationships. Histology showed myocardial connections between MS and LAm. STUDY LIMITATIONS:The study limitations included postmortem material from warmblood horses, single-observer measurements and lack of in vivo assessment. CONCLUSIONS:Coronary sinus/GCV trajectory is important for optimal catheter positioning. Right atrial MS might contribute to arrhythmogenesis, and tributary variations may impact CS/GCV catheterisation in horses.

In this study, the irregular contours of the femoral condyle surface are examined by radiographic imaging and their link to the subchondral ossification process in fetal, prenatal and neonatal foals is investigated. The goal was to determine if these irregularities are normal develop-mental variations or signs of pathology. A post-mortem study was performed on 27 stifles from 14 normal foals and fetuses. Radiographic imaging, CT and CT arthrography were followed by a histopathological examination of the articular-epiphyseal cartilage complex (AECC). Histories of the foals were recorded, with causes of death unrelated to the study. Femoral condyles with lytic or cystic changes were excluded. The femoral condyles were evaluated and graded on a scale from 1 to 4. All foals showed irregular outlines of the medial femoral condyle, which correlated with normal ossification and vascular development and decreased as endochondral ossification progressed, indicating they are part of a normal physiological process.

All birds possess a unique venous architecture surrounding the kidneys known as the renal portal system. In veterinary medicine, this system is well known for causing a first-pass effect when medication is administered parenterally via the leg veins, that is venous blood from the leg is filtered before entering general circulation, thus possibly compromising adequate dosage. Additionally, bilateral valves are present in these veins, and it has been hypothesized that they play a crucial role in regulating flow through the kidneys to protect them against increases in blood pressure. While this hypothesis has been acknowledged, it has not been thoroughly explored. We propose that the function of the renal portal valve extends beyond its significance for kidney function, potentially impacting general hemodynamics. Examining anatomical similarities with extant non-avian reptiles, which lack the renal portal shunt with valve, could reveal additional functionalities of this system in birds. Given the endothermic metabolism and the energetically expensive locomotor activity of birds, the resistance of the hepatic and renal portal system might constrain the blood flow from splanchnic to non-splanchnic blood vessels necessary for (sustained) peak performance. Therefore, diverting blood from the renal portal system using the renal portal valve as a regulatory structure might represent a key adaptation to facilitate sustained peak performance. In addition, we hypothesize that this shunt and valve represents a very early adaptation in amniotes, possibly lost in extant non-avian reptiles but enhanced in birds, with a pivotal role in maintaining hemodynamic homeostasis to support the high metabolic rates characteristic of birds.

Vascular corrosion casting is a method used to visualize the three dimensional anatomy and branching pattern of blood vessels, guiding insight into health and cardiovascular disease pathogenesis and progression. A polymer resin is injected in the vascular system and, after curing, the surrounding tissue is removed. This corrosion process often deforms or even fractures the fragile cast, resulting in an overall loss of information. Here, we propose a method that does not require corrosion of the tissue, based on in-situ high-resolution computed tomography (micro-CT) scans. Since there is a lack of CT contrast between the polymer cast and the animals’ surrounding soft tissue, we introduce hafnium oxide nanocrystals (HfO2 NCs) as CT contrast agents into the resin. The NCs dramatically improve the overall CT contrast of the cast and allow for straightforward segmentation in the CT scans. We designed the NC surface chemistry to ensure colloidal stability of the NCs in the casting resin, resulting in a homogeneous dispersion that remains stable during casting and curing. Using only 5 m% of HfO2 NCs, high-quality casts of both zebrafish and mouse models could be segmented using CT imaging software, allowing us to differentiate even μm scale details, without having to alter the resin injection method or affecting the resin’s mechanical properties. Our new method of virtual dissection by visualizing casts in-situ using contrast enhanced CT imaging greatly expands the application potential of the technique.

BACKGROUND:Three-dimensional electro-anatomical mapping, previously performed in horses with atrial arrhythmias, has demonstrated the medial region of the caudal vena cava (CaVC), 1-8 cm caudal to the fossa ovalis, as an anatomical predilection site for atrial tachycardia associated with areas of slow conduction and conduction block. Slow conduction has also been recorded in the cranial vena cava (CrVC). OBJECTIVES:To investigate the morphological characteristics of the myocardial sleeves (MS) in the CaVC and CrVC, in order to identify a potential substrate of right sided atrial arrhythmias. STUDY DESIGN:Cross sectional. METHODS:Post-mortem dissection of 37 hearts from adult warmblood horses without known cardiovascular disease. Macroscopic examination of the myocardial distribution, evaluated the MS area, length, width, and shape in the CaVC and the CrVC. At least 2 samples from each vena cava MS were histologically examined using Masson's trichrome staining. RESULTS:Myocardial sleeves into the medial CaVC and into the CrVC were observed in all horses and showed variations in distribution, shape, and size between horses. Their mean ± standard deviation length from the limbus into the CaVC reached 5.7 ± 1.0 cm (maximum 8.3 cm), and from the azygos vein into the CrVC 5.3 ± 1.6 cm (maximum 8.6 cm). Myocardium-free islands were observed in the CaVC and CrVC in 30% and 6% of horses, respectively. Histologically, MS showed a non-uniform myocardial fibre arrangement, with presence of fibroadipose tissue, features known to result in slow conduction and pro-arrhythmia. MAIN LIMITATIONS:Study only included horses without history of atrial arrhythmia. CONCLUSIONS:Myocardial sleeves are present in both CaVC and CrVC, showing anatomical variations between horses. Tissue characteristics known to favour re-entry were identified indicating that these venae cavae MS are a potential substrate for atrial tachyarrhythmias and a target for treatment by ablation.

The phrenic lymph node (PLN) has been described in bovine, equine, and feline anatomic references but descriptions in canine anatomic references are currently lacking. Authors have observed a well-defined, soft tissue attenuating, contrast-enhancing structure in a location consistent with previous anatomic descriptions of the PLN in dogs that underwent thoracic CT for neoplastic staging. The aims of this two-part, retrospective/prospective, anatomic, prevalence study were (1) to describe the presence of a soft tissue structure close to the thoracic caudal vena cava, defined as the presumed PLN, in a series of dogs that underwent CT as part of the staging for metastatic disease; (2) to confirm the lymphatic origin of the presumed PLN in a dog through postmortem examination; (3) to assess the prevalence of the presumed PLN in a population of dogs that underwent thoracic CT or MRI for different clinical purposes; and (4) to assess the possibility to visualize the presumed PLN with ultrasonography. The lymphatic origin of the presumed PLN was confirmed by postmortem examination in one dog. The presumed PLN was visible in 29 of 777 canine CT examinations (prevalence 3.7%). The presumed PLN was not visible in 9 of 10 prospectively recruited ultrasound cases. Most dogs with visible presumed PLNs were large-medium breeds that were presented for neoplastic staging purposes. Findings indicated that a structure consistent with the previously reported anatomic features of PLN in cattle, horses, and cats may be detected with a low prevalence in canine CT and MRI examinations.

BACKGROUND:The need for proper age determination in puppies has increased enormously due to the growing illegal trade in puppies that are too young to be removed from the litter or too young to have been properly vaccinated against rabies.METHODS:Dorsopalmar and mediolateral radiographs of the (meta)carpal region, either taken from puppy cadavers or from the Faculty's patient database, were studied in a cross-sectional study of 252 puppies of various sizes, aged 6-212 days. The appearance and development of ossification centres as a function of age in five regions of interest in the (meta)carpal region were scored using a two- to six-step scoring system based on shape and delineation.RESULTS:A positive correlation with age was found for all investigated regions. Intra- and interrater agreement between two observers was excellent, except for the distal epiphyses of the metacarpal bones. Postnatal ossification started after the second week of life with the carpal bones, closely followed by the radial trochlea. All ossification centres were present in all puppies from 84 days, except for the sesamoid bone in the tendon of the long abductor muscle of the first digit. Timing of appearance differed significantly between different sized breeds. There were no significant differences between the sexes.LIMITATIONS:Age distribution was not balanced for all breed size classes.CONCLUSIONS:The radiographic timing of the appearance and development of ossification centres in the carpal region is a promising method for age estimation in puppies.

The primate scapula has been studied widely since its shape has been shown to correlate with how the forelimb is used in daily activities. In this study, we expand on the existing literature and use an image-based methodology that was originally developed for orthopaedic practice to quantify and compare the three-dimensional (3D) morphology of the scapula across humans and great apes. We expect that this image-based approach will allow us to identify differences between great apes and humans that can be related to differences in mobility and loading regime of the shoulder. We hypothesize that gorillas and chimpanzees will have a similar scapular morphology, geared towards stability and weight-bearing in knuckle-walking, whilst the scapular morphology of orangutans is expected to be more similar to that of humans given their high glenohumeral mobility associated with their suspensory lifestyle. We made 3D reconstructions of computed tomography scans of 69 scapulae from four hominid genera (Pongo, Gorilla, Pan and Homo). On these 3D bone meshes, the inferior glenoid plane was determined, and subsequently, a set of bony landmarks on the scapular body, coracoid, and acromion were defined. These landmarks allowed us to measure a set of functionally relevant angles which represent acromial overhang, subacromial space and coracoacromial space. The angles that were measured are: the delto-fulcral triangle (DFT), comprising the alpha, beta, and delta angle, the acromion-glenoid angle (AGA), the coracoid-glenoid centre-posterior acromial angle (CGA), the anterior tilt (TA CGA) and the posterior tilt of the CGA (PT CGA). Three observers placed the landmarks on the 3D bone meshes, allowing us to calculate the inter-observer error. The main differences in the DFT were found between humans and the great apes, with small differences between the great apes. The DFT of humans was significantly lower compared to that of the great apes, with the smallest alpha (32.7 degrees), smallest delta (45.7 degrees) and highest beta angle (101.6 degrees) of all genera. The DFT of chimpanzees was significantly higher compared to that of humans (p < 0.01), with a larger alpha (37.6 degrees) and delta angle (54.5 degrees) and smaller beta angle (87.9 degrees). The mean AGA of humans (59.1 degrees) was significantly smaller (p < 0.001) than that of gorillas (68.8 degrees). The mean CGA of humans (110.1 degrees) was significantly higher (p < 0.001) than in orangutans (92.9 degrees). Humans and gorillas showed mainly a posterior tilt of their coracoacromial complex whilst chimpanzees showed mainly an anterior tilt. The coracoacromial complex of the orangutans was not tilted anteriorly or posteriorly. With our image-based method, we were able to identify morphological features of the scapula that differed significantly between hominid genera. However, we did not find an overall dichotomy in scapular morphology geared towards high stability (Pan/Gorilla) or high mobility (Homo/Pongo). Further research is needed to investigate the functional implications of these differences in scapular morphology.

Corrosion casting based on the curing of acrylic resins enables one to create casts as replicas of body systems, enhancing our knowledge of veterinary medicine. The identification of the optimal chemical formulations as well as the processing conditions, the delivery of good control during the liquid state and the excellent macroscopic properties during solidification and after use are remaining challenges. In the present work, based on the identification of more qualitative trends, it is demonstrated that multicomponent comonomer mixtures are interesting materials that can be used to expand the range of mechanical properties and can specifically result in a better balance between stiffness and flexibility while guaranteeing dimensional stability. Emphasis is put on a large pool of formulations in the testing phase to then perform a detailed mechanical flexural analysis for the most promising cases during a more rigorous testing phase, accounting for a new pragmatic protocol for the pot life. This protocol consists of a vial-based turning test and a measurement of the viscosity variation up to 1000 mPa∙s and highlights the complex interplay between the overall initial concentrations and the impact of the absence of mixing once the system is at rest. It is demonstrated that the use of only low-molar-mass crosslinkers should be avoided, and overall, an intermediate amount of crosslinkers is recommendable.

This study investigated the influence of several covariates on the time and sequence of permanent dentition emergence following exfoliation of the deciduous teeth in puppies. The aim was to determine whether the emergence of permanent dentition can be used to assess whether a puppy that is traded across borders in the EU has reached the legally required minimum age of 15 weeks. The events were evaluated in a longitudinal study, with some cross-sectional observations, of 440 puppies belonging to 82 breeds. No significant differences were found between the left and right sides of a puppy's dentition nor between male and female puppies. Breed size and skull type had a significant impact: both the appearance and the completion of tooth eruption occurred considerably later in small or toy breeds and brachycephalic skull type breeds. The sequence of emergence differed little between maxillary or mandibular quadrants or between breeds. The first emerging elements were the maxillary first premolars or first incisors or the mandibular first incisors. The emergence of a permanent tooth usually occurred within 3 days before or after exfoliation of its precursor, except for the canines, which demonstrated a wider tooth replacement interval. This study presents standards for age assessment based on the emergence of permanent dentition for breeds of different sizes, using median ages or cumulative emergence percentages. However, the legal age determination of puppies with an assumed age of 15 weeks cannot be performed based on permanent dentition emergence, as this occurred at a later age in a large proportion of dogs (at least 95%) in our studied population. The probability of being at least 15 weeks old when at least one maxillary tooth has emerged was at least 72.25%, depending on breed size.

Age estimation in adult dogs can be performed by the radiographic measurement of the tooth pulp cavity, but the technique has hardly been described. In this study, the application of measuring pulp/tooth width ratios (P/T ratios) of the maxillary canine teeth was investigated. Pulp and tooth widths were measured at two locations on 166 maxillary canine teeth of the heads of 84 dog cadavers, using digital extraoral lateral oblique open mouth radiographs. The dogs belonged to different breeds and sexes and had a known age between 194 and 1907 days (approximately 6 months to 5 years). Both at the cemento-enamel (CE) junction and the half-height of the tooth, a comparable non-linear regression with age was demonstrated. Measuring at the CE location was less hindered by wear or superimposition. No statistically signi fi cant difference according to sex and breed size and no clinically signi fi cant difference according to skull type was found. The highest predictable capacity was found in the youngest dogs until the age of 448 days, of which 84.4% of the canine teeth had a P/T ratio above 0.39. Our results demonstrate that measuring P/T ratios of canine teeth can be used in practice to assign dogs to age categories, with the highest accuracy in young adult dogs.

The lymphatic system maintains tissue homeostasis by transporting the excess fluid from the interstitium and ultimately returning it to the venous circulation against an adverse pressure gradient and gravitational force. The spontaneous contractions of lymphangions, the building blocks of collecting vessels, and the secondary lymphatic valves play key roles in lymph propulsion. The aim of this study was to investigate lymph propulsion in a series of three contracting lymphangions in a 3D reconstructed model segmented from micro-CT scans of the collecting lymphatics in the hind limb of mice. Computational Fluid Dynamics and Fluid–Structure Interaction were used to study the behavior of flow within the collecting vessel, as well as the behavior and deformations of the vessel wall and the poroelastic interstitium. The secondary valves were modelled as porous membranes with closed or open states depending on their permeability. A sensitivity study revealed that the parameters having the most impact on the total volume of lymph propelled by active contraction of the lymphangions were the elastic modulus of the interstitium and the permeability of the secondary valves during the open states.

Age estimation in adult dogs can be performed by the radiographic measurement of the tooth pulp cavity, but the technique has hardly been described. In this study, the application of measuring pulp/tooth width ratios (P/T ratios) of the maxillary canine teeth was investigated. Pulp and tooth widths were measured at two locations on 166 maxillary canine teeth of the heads of 84 dog cadavers, using digital extraoral lateral oblique open mouth radiographs. The dogs belonged to different breeds and sexes and had a known age between 194 and 1907 days (approximately 6 months - 5 years). Both at the cemento-enamel junction (CE) and the half-height of the tooth, a comparable non-linear regression with age was demonstrated. Measuring at the CE location was less hindered by wear or superimposition. No statistically significant difference according to sex and breed size and no clinically significant difference according to skull type was found. The highest predictable capacity was found in the youngest dogs until the age of 448 days, of which 84.4% of the canine teeth had a P/T ratio above 0.39. Our results demonstrate that measuring P/T ratios of canine teeth can be used in practice to assign dogs to age categories, with the highest accuracy in young adult dogs.