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The sesamoid bone in the tendon of the m. abductor digiti primi longus is considered present in most dog breeds and is described to be radiologically detectable at the level of the carpus from the age of 4 months. However, an extensive investigation of this sesamoid bone has not been conducted before. The aim of this study was therefore to determine its prevalence in different dog breeds, to describe its histological development, and to determine the age at which it becomes radiologically visible. The prevalence of the sesamoid bone was assessed on radiographic images of the carpus or by dissection of the carpal region in 743 adult dogs of 115 breeds. Its development was studied by dissection and histological analysis in 45 puppies and its timing of radiological appearance was evaluated in 209 puppies. At least one sesamoid bone was present in all adult dogs, except for 14 dogs of six breeds of predominantly the small breed category. The lowest prevalence rate of 38.46% was exhibited in the French bulldog. The histological development could be divided into five stages. The first radiographic appearance corresponded to the coalescence of smaller ossification centers into one big nucleus (stage 4). The mean time of radiographic appearance was 108.4 days. This study provides extensive data on the prevalence and timing of the radiographic appearance of a sesamoid at the carpus of the dog. The data on radiographic appearance may be helpful in the age estimation of puppies.

Objective To develop an ultrasound (US)-guided transversus abdominis plane (TAP) block in pigs. Study design Prospective, descriptive, experimental study. Animals A total of 26 hemi-abdomens belonging to 13 Seghers Hybrid cadavers. Methods The study consisted of two parts. In part 1, a preliminary anatomical understanding of the abdominal wall innervation in pigs was established (two hemi-abdomens of one pig). Part 2 was divided into three phases, and a US-guided TAP technique using methylene blue dye (0.3 mL kg–1 for each hemi-abdomen) was developed. In chronological order, a pilot study (phase I) was conducted to establish good injection points (four hemi-abdomens). In phase II a two-point injection technique (10 hemi-abdomens) was performed. A cranial injection was made at two-thirds of the distance between the xyphoid process and the iliac crest, immediately ventral to the rib arch. A caudal injection was performed ventral to the last rib. In phase III a three-point injection technique was performed (10 hemi-abdomens) with an extra injection point halfway between the cranial and caudal injection point. Staining of the different nerves was recorded during dissection. Results In part 1 the nerves innervating the pig’s abdominal wall, thoracic vertebrae 12–16 (T12–16) and lumbar vertebrae 1–3 (L1–3), were identified. In part 2, data from the pilot study, adequate nerve staining with the two- or three-point injection technique, were obtained in T12 (29 versus 45% respectively), T13 (29 versus 100%), T14 (73 versus 45%), T15 (75 versus 78%), T16 (58 versus 78%), L1 (100 versus 75%), L2 (88 versus 84%) and L3 (23 versus 0%). Conclusions and clinical relevance US-guided TAP block can be used in swine but only a moderate success rate for adequate nerve staining was achieved in this study. Further studies are necessary to determine a correct injection volume and assess clinical intra- and postoperative efficacy.

BACKGROUND Echocardiography is the imaging technique of choice for the equine heart. Nevertheless, knowledge about ultrasonographic identification of dorsally located structures and vessels, related to the atria, in horses is scarce. OBJECTIVES To describe the echocardiographic approach and the identification of structures and vessels in relation to the atria in healthy horses. METHODS CT images from two equine hearts, casted with self-expanding foam, were segmented and used to identify atrial-related structures and vessels. These images were compared with standard and nonstandard ultrasound images from ten healthy horses obtained from a left and right parasternal view optimised to visualise the dorsal cardiac area. RESULTS On new standard ultrasound views, specific atrial anatomical landmarks such as vena cava, pulmonary arteries, intervenous tubercle and oval fossa were identified in all horses. In addition, ultrasound views were defined to visualise the brachiocephalic trunk, pulmonary veins and their ostia. The 3D segmented CT images from casted hearts were used to reconstruct slices that corresponded with the echocardiographic images and allowed correct identification of specific structures. MAIN LIMITATIONS Ultrasound examinations and casts were from different animals. A small number of casts and horses were used; therefore, anatomical variation or individual differences in identifying structures on ultrasound could not be assessed. CONCLUSIONS Important cardiac structures and vessels, even the different pulmonary veins, could be identified on standard and nonstandard ultrasound images in adult horses. This knowledge is important to guide and develop interventional cardiology and might be useful for diagnostic and therapeutic purposes.

Background: Recurrence of atrial fibrillation after an ablation procedure remains a major problem which emphasizes the need for improved pulmonary vein isolation techniques. Aims: The aim of this study was to describe an implantation procedure of a pulmonary vein-stent which may possibly serve as an ablation technique in the future and to examine stent safety in a follow-up study in pigs. Methods and results: Eight pigs were catheterized and nine self-expanding nitinol stents were implanted through a transfemoral or transatrial approach into the antra of the pulmonary veins. After 3 months' follow-up, the animals were euthanized for further examination. During the follow-up phase, no complications were observed. Absence of thrombus formation or pulmonary vein wall dissection was noticed during anatomical and histological evaluation of the heart-lung packages. All implants were almost completely covered by neo-intima, of which thickness varied between 0.2 and 3.9mm. Conclusions: Stents can safely be positioned and deployed into the antra of the pulmonary veins without any acute or long-term (3 months) adverse effects. In the future, these implants could function as a permanently implanted ablation device and provide new therapeutic strategies for pulmonary vein isolation in patients with atrial fibrillation.

Objective To investigate the anatomy of the ear innervation in horses and develop a new approach for the block of the internal and external pinna and acoustic meatus. Study design Prospective, descriptive, cadaveric study. Animals A total of 25 heads and necks from horse cadavers. Methods Phase I: anatomical dissection and dye deposition on 19 heads. With the head positioned in lateral recumbency, 10 mL methylene blue (1:1 sterile water) for the internal auricular and 2 mL for the great auricular nerve block were injected in 21 ears (seven left, 10 right and two bilaterally). The anatomy of all the ears (bilaterally) and the accuracy of dye deposition (successful nerve staining defined as > 2 cm) was assessed following dissection. Occurrence of intraparotid, intravascular, or intraneural injection was recorded. Phase II: the same technique and volumes were applied, bilaterally, using a lidocaine 2%:iohexol solution mixture (3:1) in six different cadavers. Computed tomography was performed and the needle position and spread of the mixture evaluated and recorded. Results Phase I: Inter- and intraindividual differences were found in the anatomy of the great auricular nerve, but not in the internal and lateral auricular nerve branches and the caudal auricular nerve. No auriculotemporal nerve was found. Nerve staining was successful in 95% of the cases for the great auricular nerve, 85% of the cases for the internal auricular nerve, and 100% of the cases for the lateral auricular branch and caudal auricular nerve. Failure was observed in horses with abundant periauricular fat. No intravascular, intraparotid or intraneural injections occurred. Phase II: A 100% success rate was recorded from computed tomography images. Conclusions and clinical relevance The described approach seems suitable for blockade of the sensory innervation of the equine ear.

Ganglia and telocytes were identified inside the porcine pulmonary veins wall near myocardial sleeve tissue at the atriopulmonary junction. These structures are reported to play a role in the initiation of pulses from outside the heart, which potentially can cause cardiac conduction disorders such as atrial fibrillation. In-depth knowledge on the fine structure of the pulmonary vein wall is a pre-requisite to better understand the underlying pathophysiology of atrial fibrillation and the origin and conduction of ectopic pulses. The importance of pulmonary vein myocardial sleeves as triggering foci for atrial fibrillation has been shown in human patients. In this context, the fine structure of the pulmonary vein wall was investigated qualitatively by light and transmission electron microscopy in the pig, which is a frequently used animal model for development of new treatment strategies. Additionally, intra and extramural ganglia, containing telocytes that create a network near the neurone cell bodies, were identified in pigs. Detailed illustration of the distribution and organization of tissues and cell types, potentially involved in the origin and propagation of ectopic stimuli originating from the pulmonary veins, might lead to a better insight on the actual composition of the tissues affected by ablation as studied in pigs.

Piglets are considered to be suitable animal models for predicting the pharmacokinetics and pharmacodynamics (PK/PD) of test drugs for potential use in the paediatric population. Such PK/PD studies require multiple blood and urine samplings. The goal of the present study was to determine a suitable blood collection strategy applicable in the youngest age categories of six days, four weeks and eight weeks of age, as well as a urine collection technique for male piglets in the same age categories. Blood was collected either by a surgically-placed jugular vein catheter (six days old [ n = 4] and four weeks old [ n = 2] piglets) or by direct venepuncture of the jugular vein (four weeks old [ n = 2] and eight weeks old [ n = 4] piglets). A non-invasive method for total volume urine collection in male piglets was also developed using a urine pouch. No specific complications were encountered during anaesthesia or surgery for jugular catheter placement. After a 24 h recovery period, urine and blood were easily collected without technical complications. One piglet was humanely killed at week 2 because of septicaemia. Histological analysis of both veins in all four piglets revealed negligible damage to the blood vessel wall. In conclusion, the presented techniques for blood (jugular catheter and direct venepuncture) and urine collection (pouches) are suitable for PK/PD studies in piglets.

Objective: To expand current knowledge on the canine omental vasculature and refine the existing lengthening technique of the canine omentum. Study Design: Ex vivo study. Animals: Canine cadavers (n=20). Methods: In 10 canine cadavers the omental arteries were mapped using intravascular latex injection and these results were used to create an omental pedicle flap based on the splenic artery in 10 additional cadavers. The operating range of the flap was recorded with particular attention to the main regions of interest for omental transposition in dogs (axillary and inguinal regions). Results: The superficial and deep omental leaves were each predominantly supplied by a left and a right marginal omental artery that anastomosed near the caudal omental border into a superficial and a deep omental arch, respectively. Anastomoses between arteries of the superficial and the deep omental leaves were weak and inconsistent, except for 1 anastomosis that was found in 8 of 10 dogs. By transposing the intact omentum, the right axilla could be reached in 3 dogs, both axillae in 1 dog, and both groins in all cadavers. In all cases, the omental pedicle reached to and beyond the axillary and inguinal regions. By unfolding the pedicle leaves, the width of the pedicle tip could be doubled. Conclusion: When lengthening the omentum is necessary to reach extra-abdominal structures, the omental pedicle flap based on the splenic artery appears to preserve the omental vascular supply. These observations warrant further clinical trials to evaluate this new omtental flap technique in vivo.

Background Atrial fibrillation is the most frequent arrhythmia in adults of which the interventional cure is hampered by high recurrence rates. Recurrence after ablation is due to an incomplete isolation of the pulmonary veins. A new ablation technique was performed, in the antra of ovine pulmonary veins, by device implantation, which was heated through a wireless heat-generating system. Methods and Results Implants were placed transatrially in the pulmonary veins of sheep. Using a wireless heating system, the energy was afterward transferred through wires to the implanted device according to a defined protocol. The position of the implant and the applied lesions were macroscopically evaluated. Samples of the ablated tissue of the atrio-pulmonary vein junction were histologically and immunohistochemically examined. Conclusions Six ablation procedures in four sheep were successfully performed without adverse cardiac reactions. Implantation of the device and the wireless heat generation was feasible. Sufficient heat was produced at the level of the antra of the pulmonary veins to create ablation lesions, which were histologically and immunohistochemically confirmed.

During endoscopy (tenoscopy) of the distal aspect of the equine digital flexor tendon sheath (DFTS), the digital manica flexoria can be visualized connecting the distal branches of the superficial digital flexor tendon. However, this structure has been inconsistently described and variably named in the veterinary literature. The objectives of this study were to describe the presence, configuration and variability of the digital manica flexoria in the equine distal limb. Dissection of 144 equine cadaveric limbs revealed the presence of this structure in all the feet, although different types and conformations were identified. In the forelimbs, a membranous digital manica flexoria predominated (94%; P

An Oldenburg colt with wry nose was autopsied after having lived for only 30 min. It presented cyanotic oral mucosae, underdeveloped eyes and a right-sided temporal osseous mass. The applicable nomenclature for the defects is discussed, and the potential etiopathogenesis is explored by describing the normal embryonic development of the affected body parts.

International audience; Cirrhosis represents the end-stage of any persistent chronically active liver disease. It is characterized by the complete replacement of normal liver tissue by fibrosis, regenerative nodules, and complete fibrotic vascularized septa. The resulting angioarchitectural distortion contributes to an increasing intrahepatic vascular resistance, impeding liver perfusion and leading to portal hypertension. To date, knowledge on the dynamically evolving pathological changes of the hepatic vasculature during cirrhogenesis remains limited. More specifically, detailed anatomical data on the vascular adaptations during disease development is lacking. To address this need, we studied the 3D architecture of the hepatic vasculature during induction of cirrhogenesis in a rat model. Cirrhosis was chemically induced with thioacetamide (TAA). At predefined time points, the hepatic vasculature was fixed and visualized using a combination of vascular corrosion casting and deep tissue microscopy. Three-dimensional reconstruction and data-fitting enabled cirrhogenic features to extracted at multiple scales, portraying the impact of cirrhosis on the hepatic vasculature. At the macrolevel, we noticed that regenerative nodules severely compressed pliant venous vessels from 12 weeks of TAA intoxication onwards. Especially hepatic veins were highly affected by this compression, with collapsed vessel segments severely reducing perfusion capabilities. At the microlevel, we discovered zone-specific sinusoidal degeneration, with sinusoids located near the surface being more affected than those in the middle of a liver lobe. Our data shed light on and quantify the evolving angioarchitecture during cirrhogenesis. These findings may prove helpful for future targeted invasive interventions

Necropsy examination of an adult neutered male cat, which was humanely destroyed as it had feline immunodeficiency virus (FIV) infection, demonstrated the presence of a left retrocaval ureter that was entrapped around the left limb of a double caudal vena cava. These associated anomalies originate from the complex embryofetal development of the caudal vena cava. Since no clinical signs had been reported and no gross lesions related to this anomaly were observed, this manifestation should be simply considered as an anatomical variation.

The myocardial sleeve of the porcine and equine pulmonary veins were histologically investigated and reconstructed three dimensionally. Moreover, the localization of neuron cell bodies at the veno-atrial junction and alongside the myocardial sleeve was light microscopically visualized to depict the organization of nerve, myocardial and fat tissue. Finally, the presence of telocytes inside the equine pulmonary veins was demonstrated by use of transmission electron microscopy. These structures are thought to play a role in the induction of atrial fibrillation, which is frequently seen in horses, while pigs are often used as a cardiovascular model in this context. This data fills in remaining gaps in the literature concerning the histological build-up of the pulmonary veins wall in pigs and horses. In-depth knowledge on the myocardial sleeve and its surrounding cell types are important to understand the possible outcome of an ablation therapy as an atrial fibrillation treatment. In pigs and horses, the layout of the pulmonary veins wall concerning these structures is comparable to humans. However, neuron cell bodies were recovered at the veno-atrial junction in both species but not alongside the myocardial sleeve in horses.

The intricate (micro)vascular architecture of the liver has not yet been fully unravelled. Although current models are often idealized simplifications of the complex anatomical reality, correct morphological information is instrumental for scientific and clinical purposes. Previously, both vascular corrosion casting (VCC) and immunohistochemistry (IHC) have been separately used to study the hepatic vasculature. Nevertheless, these techniques still face a number of challenges such as dual casting in VCC and limited imaging depths for IHC. We have optimized both techniques and combined their complementary strengths to develop a framework for multilevel reconstruction of the hepatic circulation in the rat. The VCC and micro-CT scanning protocol was improved by enabling dual casting, optimizing the contrast agent concentration, and adjusting the viscosity of the resin (PU4ii). IHC was improved with an optimized clearing technique (CUBIC) that extended the imaging depth for confocal microscopy more than five-fold. Using in-house developed software (DeLiver), the vascular network in both VCC and IHC datasets was automatically segmented and/or morphologically analysed. Our methodological framework allows 3D reconstruction and quantification of the hepatic circulation, ranging from the major blood vessels down to the intertwined and interconnected sinusoids. We believe that the presented framework will have value beyond studies of the liver, and will facilitate a better understanding of various parenchymal organs in general, in physiological and pathological circumstances. Key words: 3D modeling; confocal laser scanning; hepatic vasculature; immunohistochemistry; micro-CTscanning; morphological analysis; rat liver; vascular corrosion casting.

Although the omentum remains an enigmatic organ, research during the last decades has revealed its fascinating functions including fat storage, fluid drainage, immune activity, angiogenesis and adhesion. While clinicians both in human and veterinary medicine are continuously exploring new potential omental applications, detailed anatomical data on the canine omentum are currently lacking, and information is often retrieved from human medicine. In this study, the topographic anatomy of the canine greater and lesser omentum is explored in depth. Current nomenclature is challenged, and a more detailed terminology is proposed. Consistent arteries that are contained within folds of the superficial omental wall are documented, described and named, as they can provide the anatomical landmarks that are necessary for unambiguous scientific communication on the canine omentum. In an included dissection video, the conclusions and in situ findings described in this study are demonstrated.

Summary Reasons for performing study There are no previous studies correlating the anatomy of the equine epiploic foramen and its defining structures with laparoscopic images. Objectives The purpose of this study was to describe the precise anatomy of the epiploic foramen and omental vestibule, to quantify the dimensions of the epiploic foramen and to relate these findings to laparoscopic images. Study design Descriptive study of cadaver material and laparoscopic images. Methods Thirty-two horses subjected to euthanasia for reasons unrelated to colic were studied. Two cadavers were used to make vascular casts of the coeliac artery and portal vein. In 30 cadavers the epiploic foramen and omental vestibule were cast with a polyurethane prepolymer immediately after euthanasia. The cast served as a landmark during dissection and the circumference of the epiploic foramen was measured from these casts. Histology was performed on structures defining the epiploic foramen in 2 horses. Laparoscopic images from 6 standing right flank procedures were reviewed. Results The defining structures of the epiploic foramen and omental vestibule are the hepatoduodenal ligament, hepatogastric ligament and the gastropancreatic and hepatopancreatic folds. The hepatoduodenal ligament has a secondary fold which forms the ventral border of the epiploic foramen, consisting of a central connective tissue core of mainly elastin fibres. The hepatic artery for part of its course is incorporated in the hepatoduodenal ligament. All these structures are clearly visible laparoscopically. The mean circumference of the epiploic foramen is 11.6 ± 2.6 cm and its circumference is positively correlated with body weight but is unrelated to age or gender. Conclusions Several clinically relevant structures delineate the epiploic foramen. Its defining structure consists, in part, of elastin fibres. Anatomical and laparoscopic knowledge may assist surgeons in developing interventions to treat diseases involving the epiploic foramen.

Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, BelgiumCorresponding AuthorIlona Schwarzkopf, DVM, DAC Malpertuus,Leenstraat 2a, 9070 Heusden, O.VL,Belgium.E‐mail: ilona.schwarzkopf@gmail.comSubmitted September 2012Accepted March 2013DOI:10.1111/j.1532-950X.2014.12226.x

Persisterende ductus arteriosus (PDA) is één van de meest vastgestelde congenitale hartaandoeningen bij de hond. Indien de aandoening niet behandeld wordt, sterft meer dan de helft van de honden in hun eerste levensjaar. Het sluiten van de PDA via occlusie of ligatie is dan ook aanbevolen en heeft een goede langetermijnprognose. De belangrijkste complicatie bij de nietinvasieve technieken is het optreden van embolie terwijl bloeding na ruptuur van de ductus of een naburig bloedvat het meest voorkomende probleem is bij ligatietechnieken. Twee gevallen van PDA worden hier besproken. Bij de eerste hond werd de PDA succesvol chirurgisch gecorrigeerd. Bij de tweede hond daarentegen ontstonden er tijdens de chirurgische ingreep meermaals ernstige bloedingen te wijten aan de uitzonderlijke aanwezigheid van een persisterende vijfde aortaboog (PFAA). Er werd intraoperatief besloten om tot euthanasie over te gaan.

The layout of the porcine atriopulmonary junction and immediately adjacent structures was investigated by gross anatomical and vascular corrosion casting studies to meet the need for more in-depth anatomical insights when using the pig as an animal model in the development of innovative approaches for surgical cardiac ablation in man. The veins from the right cranial and middle lung lobes drain through a common ostium in the left atrium, whereas a second ostium receives the blood returning from all other lung lobes, although limited variation to this pattern was observed. Surrounding anatomical structures that are most vulnerable to ablation damage as reported in man are located at a safer distance from the pulmonary veins in pigs, yet a certain locations, comparable risks are to be considered. Additionally, it was histologically confirmed that myocardial sleeves extend to over a centimetre in the wall of the pulmonary veins.

A three-year-old neutered male whippet was presented with intermittent, exercise-induced paraparesis. Femoral pulses were bilaterally absent. Neurologic examination was suggestive of a thoracolumbar myelopathy. Blood pressure measurements revealed hypotension in both pelvic limbs, hypertension in the right thoracic limb and it was immeasurable in the left thoracic limb. Echocardiography was within reference limits. A clear vascular pulsation was palpable on the right ventral abdominal wall. Computed tomographic angiography revealed a dissection of the aortic wall between the left subclavian artery and the brachiocephalic trunk with subsequent thrombus formation. A shunt between the right internal thoracic, cranial and caudal epigastric arteries to preserve blood flow to the pelvic limbs was visualized. Necropsy was declined by the owner. This is the first case report describing the formation of a unilateral vascular shunt following a thoracic aortic occlusion, which presented as exercise-induced paraparesis.

Although the murine thoracic aorta and its main branches are widely studied to gain more insight into the pathogenesis of human vascular diseases, detailed anatomical data on the murine aorta are sparse. Moreover, comparative studies between mice and men focusing on the topography and geometry of the heart and aorta are lacking. As this hampers the validation of murine vascular models, the branching pattern of the murine thoracic aorta was examined in 30 vascular corrosion casts. On six casts the intrathoracic position of the heart was compared with that of six younger and six older men of whom contrast-enhanced computer tomography images of the thorax were three-dimensionally reconstructed. In addition, the geometry of the human thoracic aorta was compared with that of the mouse by reconstructing micro-computer tomography images of six murine casts. It was found that the right brachiocephalic trunk, left common carotid artery and left subclavian artery branched subsequently from the aortic arch in both mice and men. The geometry of the branches of the murine aortic arch was quite similar to that of men. In both species the initial segment of the aorta, comprising the ascending aorta, aortic arch and cranial/superior part of the descending aorta, was sigmoidally curved on a cranial/superior view. Although some analogy between the intrathoracic position of the murine and human heart was observed, the murine heart manifestly deviated more ventrally. The major conclusion of this study is that, in both mice and men, the ascending and descending aorta do not lie in a single vertical plane (non-planar aortic geometry). This contrasts clearly with most domestic mammals in which a planar aortic pattern is present. As the vascular branching pattern of the aortic arch is also similar in mice and men, the murine model seems valuable to study human vascular diseases.

Contains fulltext : 89787.pdf (Publisher’s version ) (Closed access) OBJECTIVE: To evaluate the feasibility and safety of a novel percutaneous isolated liver perfusion (PILP) system in a porcine model. METHODS: The PILP catheter set, consisting of a portal vein and hepatic artery occlusion balloon and an hourglass-shaped vena cava stent-graft, was tested in six Dutch Landrace pigs. A veno-venous bypass between the distal portal vein and the right femoral vein, and isolated perfusion between the proximal portal vein and the hepatic veins were also created. Leak rate was determined using radioactivity measurement in the systemic circulation. Perfusion was then performed without (n = 2) or with cytotoxic drugs (n = 4). At the end of the procedure, all devices were retrieved and angiographic evaluation was performed of the involved vessel segments. RESULTS: In all pigs it was possible to insert, accurately position and retrieve all components of the PILP catheter set without angiographic signs of vessel-wall damage. Leakage rates to the systemic circulation were less than 7% over the course of the perfusion. CONCLUSION: In a porcine model, the PILP system can be safely and accurately positioned, and showed successful vascular isolation of the liver, with a leak rate to the systemic circulation of less than 7%. 01 oktober 2010

The reliability of a silicone double-lumen catheter implanted into the external jugular vein and tunnelled towards the neck region was investigated in eight pigs. Surgery was uneventful without interference with the normal homoeostasis during 8 days. After injection of amoxicillin/clavulanic acid through the distal port of the catheter, analysis of drug components in the simultaneous blood samples obtained by the proximal port and a Venoject system were comparable in one pig. Histological control of the catheterized jugular veins pointed to an acceptable tissue reaction while bacteriological examination of the tip of the catheters was negative in only three animals. A moulding of the intestinal veins was made in a pig cadaver to determine the optimal length of insertion of a silicone portal catheter from the splenic vein towards the portal vein. Surgery was straightforward in four pigs whereby the catheter was exteriorized towards the back region. No complications were encountered during and after surgery for 9 days. The technique of a double-lumen catheter placed into the jugular vein and a transsplenic portal catheter is a useful tool for the study of the pharmacokinetics and also the first-pass effect of drugs in experimental pigs.

The vascular topography in the lumbar region of pig embryos and young fetuses was three-dimensionally reconstructed to study some controversial aspects of the origin and development of the infrarenal part of the caudal vena cava. Contrary to general belief, it was found that the supracardinal veins, which form the azygos veins in the thorax, do not take part in the construction of the caudal vena cava in the lumbar region. These veins do appear in the abdomen, but they are only involved in the formation of the lumbar and ascending lumbar veins. The infrarenal part of the caudal vena cava arises from the lumbar part of the right caudal cardinal vein. Whilst this venous pattern is established, the lumbar part of the left caudal cardinal vein disappears and its former location is occupied by large lymphatic connections between the cysterna chyli and the retroperitoneal mesenteric lymphatic sac. On the basis of these findings, a number of hypotheses on the development of anatomical variations of the caudal vena cava should be reconsidered.

Information on ultrasound examination of equine pulmonary veins is scarce due to a lack of in-depth anatomical information. Each pulmonary vein drains a specific lung lobe region, after which those veins merge into a collecting antrum, before opening into the left atrium through their respective ostia. The aim of this study was, by using anatomical dissection and silicone casting of equine cardiopulmonary sets, to study the venous drainage of both lungs and the position of the ostia and to investigate whether the ostia can be identified and differentiated using ultrasound. Three out of the four ostia could be observed echocardiographically in the standing horse. The ostium draining the most caudal aspects of both lungs showed little variability, while the ostium draining the rest of the right lung could be used as an easily recognisable landmark, since it was located adjacent to the interatrial septum. The identification of the equine pulmonary vein ostia using ultrasound might allow for the determination of size and flow patterns in the assessment of cardiovascular disease.

Background: Ablation procedures, in the context of atrial fibrillation treatment, induce lesions which are difficult to visualize in an acute phase. This study sought to develop an immunohistochemical technique

Due to the growing shortage of donor livers, more patients are waiting for liver transplantation. Efforts to expand the donor pool include the use of living donor liver transplantation (LDLT) and split liver transplantation. LDLT involves a healthy person undergoing a partial hepatectomy to donate a part of his liver to a patient with severe liver failure. Afterwards, the regenerative capacity of the organ allows the livers of both donor and recipient to regrow to normal liver masses. The procedure is not without risk as serious complications may occur (such as cholestasis, ascites, gastrointestinal bleeding and renal impairment). An inadequate liver mass compared to the body mass may result in the small-for-size syndrome (SFSS). In both donor and recipient, LDLT may lead to portal hypertension associated with the elevated intrahepatic resistance of a smaller liver, and an increased portal venous (PV) inflow per gram of liver tissue compared to the total liver before resection. Excessive hyperperfusion and shear stress may damage the sinusoidal endothelial cells and lead to graft dysfunction.Copyright © 2013 by ASME

Reasons for performing study In man, pulmonary veins (PV) are of major importance in atrial fibrillation pathophysiology as ectopy often originates in atrial myocardial sleeves extending in the PV wall. In addition, PV size on ultrasound is used to assess left atrial volume overload. In horses, PV anatomy and ultrasound have hardly been studied. Objectives To study PV anatomy and establish a standard approach for echocardiographic identification of the PV from a right and left parasternal view. Study design Anatomical and echocardiographic description. Methods Firstly, post mortem left atrial and PV silicone corrosion casts were made in 10 horses to investigate normal PV anatomy. Secondly, left and right parasternal ultrasound images and silicone casts were made in 3 horses, to compare images and casts. Results Four major PV ostia were identified on the casts, draining specific lung areas. From a right parasternal longitudinal view, ostium III was identified between the right atrial wall and right pulmonary artery, and ostium II left-dorsal to it. From a left parasternal oblique short-axis view, ostium III, its antrum and side-branches were used as anatomical landmarks (adjacent to the right atrial wall). Slightly more caudal, ostium II was visualised with, in one horse, its antrum and 2 branches. Ostium I was only seen in one horse, slightly ventral to ostium II. Ostium IV was always identified in cross-section on a left short-axis view, left to the pulmonary artery bifurcation. Conclusions A standard echocardiographic approach allows identification of pulmonary veins in adult horses. Left oblique and short axis views were superior although right long-axis views also showed ostiums II and III. These data allow reference values to be established for pulmonary venous size and flow, and to investigate new treatment strategies for atrial fibrillation. Ethical animal research: Post mortem study with owner's informed consent; ultrasound with owner's informed consent. Study performed following the local ethical guidelines. Source of funding: Ghent University (institutional). Competing interests: None declared.

The perfusion of the liver is complex, especially at the microcirculatory level. The functional units of the liver are often schematized as hexagonal lobules (Fig. 1a), which receive blood from the peripheral portal triads (PT; including hepatic arterioles and portal venules). A part of the PT blood drains into the vascular septa (VS), which are the vascular beds delineating the lobule boundaries in between successive portal triads. Subsequently, the blood enters the interconnected network of tortuous sinusoids, where the metabolic exchange with neighboring hepatocytes takes place. Afterwards, blood drains radially into the central vein. Despite this well-known conceptual model, liver microcirculation is still not fully understood. Previously, the liver microhemodynamics have been modeled using simplified (2D) geometries and/or a porous media approach with an isotropic permeability. However, the validity of these assumptions has never been assessed. Therefore, the aim of this study was threefold. First, the (an)isotropic permeability behavior of an image-based 3D sinusoidal network was quantified using computational fluid dynamics (CFD). Secondly, the resulting permeability tensor was applied to build a 3D CFD porous medium model of a liver lobule. Thirdly, the role of VS in hepatic microperfusion was investigated by comparing a porous lobule model with and without VS.Copyright © 2012 by ASME

A two-year-old Chihuahua was presented on day 58 of pregnancy due to very marked abdominal distension. A cesarean section was performed and five normal and one clearly abnormal puppy were delivered. Examination of the abnormal puppy revealed a combination of congenital anomalies including epigastric heteropagus twinning. The autosite showed focal cranial aplasia cutis, anasarca, lissencephaly, palatoschisis, sternal agenesis and eventeratio (gastroschisis/schistocoelia). The partly formed parasitic twin was attached at the sternal region of the autosite and demonstrated four formed limbs, atresia rectum, atresia ani, a single kidney, tail agenesis and atresia vulvae. To the authors’ knowledge, this is only the third reported case of heteropagus conjoined twinning in the dog and the first reported case of canine epigastric heteropagus twinning. In addition, there appear to be no reports in the veterinary literature noting an association with conjoined twinning in the dog with focal cranial aplasia cutis, eventeratio, lissencephaly, palatoschisis and anasarca. An in-depth literature review was hampered by the lack of a uniform nomenclature to identify this type of conjoined twinning.

Due to the growing shortage of donor livers, more patients are waiting for transplantation. Living donor liver transplantation may help expanding the donor pool, but is often confronted with the small-for-size syndrome. Since the hemodynamic effects of partial hepatectomy are not fully understood, we developed an electrical rat liver model to compare normal with resected liver hemodynamics. Detailed geometrical data and 3-D reconstructions of the liver vasculature of two rats were gathered by combining vascular corrosion casting, micro-CT scanning, and image processing. Data extrapolations allowed obtaining a total liver pressure-and flow-driven electrical analog. Subsequently, virtual resections led to 70%, 80%, or 90% partial hepatectomy models. Results demonstrated hyperperfusion effects such as portal hypertension and elevated lobe-specific portal venous flows (11, 12, and 24 mmHg, and 1.0-3.0, 1.8-3.5, and 7.4 ml/min for 70%, 80%, and 90% hepatectomy, respectively). Comparison of two 90% resection techniques demonstrated different total arterial flows (0.28 ml/min versus 0.61 ml/min), portal (24 mmHg versus 21 mmHg), and sinusoidal pressures (14 mmHg versus 9.5-12 mmHg), probably leading to better survival for lower portal and sinusoidal pressures. Toward the future, the models may be extrapolated to human livers and help us to optimize hepatectomy planning.

Background: Anatomical studies of the rabbit paranasal cavities are impelled by the increasing interest in the rabbit model to investigate human sinusitis. Although several such studies have already been performed, the topography of the rabbit dorsal conchal and maxillary sinuses is described ambiguously and the existence of the ethmoidal, frontal and sphenoidal sinuses is controversial. Methodology: The paranasal cavities were investigated using corrosion casting, gross and his- tological cross-sectioning, and micro-CT scanning of rabbit noses followed by computerized three-dimensional reconstruction. Results: Micro-CT scanning was most useful to illustrate the dorsal conchal sinus, the large maxillary sinus consisting of a dorsal and a ventral recess, and the sphenoidal sinus. All these sinuses are paired and symmetrical. A large connection is present between the dorsal conchal sinus and the maxillary sinus resulting in one large conchomaxillary cavity. The sphenoidal sinus lies most caudal and is surrounded by the presphenoid bone. The openings from the nasal cavity into the conchomaxillary cavity and the sphenoidal sinus are very small. Conclusions: The absence of frontal and ethmoidal sinuses in any of the rabbits examined is a major difference between the rabbit and human sinuses. The rabbit maxillary sinus seems most appropriate for experimental work. SUMMARY

Machine perfusion (MP) is experiencing a revival in organ preservation due to the limitations of static cold storage and the need for better preservation methods for expanded criteria donors. Liver MP prototypes, however, face problems such as potential damage to sinusoidal endothelial cells, and heterogeneous perfusion related to the complex hepatic microcirculation.Copyright © 2010 by ASME

Adactyly (terminal transverse hemimelia) is a rare condition in the cat. The clinical and radiographic findings in a one-year-old cat with bilateral hindlimb adactyly are described. The cat was treated conservatively and appeared to cope well with its deformity.

Several items of the development of the caudal vena cava in domestic animals are still controversial. In particular, the origin of the lumbar segment of the caudal vena cava is equivocally described. According to different theories it originates from the right-sided supracardinal, caudal cardinal, sacrocardinal, lateral sympathetic or subcardinal veins. In this review, all five theories are compared with each other and discussed in the light of anatomical variations observed in eight dogs. Species-specific diversity, erratic observations because of technical artefacts, and biased interpretation of the original data are three major reasons for the dissimilarity between the five theories, but they cannot explain all differences. Further studies by using modern techniques such as microvascular corrosion casting and non-invasive three-dimensional microtomography are necessary to better understand the normal development and to explain the variations in domestic animal species.

Summary In this report, two cases of brachymelia in related neonatal cats are described. The malformations are described in view of normal limb development, which is illustrated by scanning electron microscopic images. Hypoplasia and aplasia of the distal limb segments were the main disorders in both kittens. Additional malformations in the second case included fusion of the radius and ulna, congenital patella luxation and a shortened tail. Brachymelia and similar cases of feline dysmelia are poorly documented in the existing literature. Possible causes and terminology of these developmental deformations are discussed.

THE occurrence of a retrocaval ureter is a well-known condition of clinical relevance in human beings (Bass and others 2000), and has also been experimentally induced in rabbits (Scortichini 1986). In human medicine, cases of a retrocaval or circumcaval ureter have a reported prevalence of 0·1 per cent at postmortem examination, with a three-fold male predominance (Singh and others 2001). The anomaly almost always occurs on the right side (Bass and others 2000), except for specific situations such as situs viscerum inversus, a genetic defect characterised by left-right inversion of asymmetric organs (Brook 1962, Mitchell and others 2003) and persistence of the left inferior vena cava (Gramegna and others 2003), in which a left retrocaval ureter can occur. In 20 per cent of cases, a retrocaval ureter is associated with other congenital defects such as hypospadia, supernumerary lumbar vertebrae, syndactylism and other abnormalities mainly of the cardiovascular or urogenital systems (Perimenis and others 2002, Friebel and others 2004). In human beings, most of these malformations remain asymptomatic (Friebel and others 2004). Clinical manifestation of pathology related to retrocaval ureter usually occurs in the third or fourth decade of the patient’s life, although some exceptional cases have been described in children (Kakanou and others 2001, Soundappan and Barker 2004). Symptoms are due to ureteral obstruction and the resulting hydronephrosis (Uthappa and others 2002). They include abdominal pain in the right flank, recurrent urinary infections, haematuria in varying degrees, urolithiasis and hypertension (Bass and others 2000, Kakanou and others 2001, Uthappa and others 2002, Soundappan and Barker 2004). Diagnosis can be made by an intravenous urogram, which demonstrates a medially deviated, inversed ‘J’-shaped or ‘S’-shaped ureter, with varying degrees of hydronephrosis (Soundappan and Barker 2004). Computer tomography and magnetic resonance imaging can also be used to diagnose clinical and asymptomatic cases of a retrocaval ureter (Uthappa and others 2002). Significant obstruction of the retrocaval ureter requires surgical correction. Transperitoneal laparotomy or laparoscopy is performed, and the ureter is sectioned, relocated in its normal anatomical position and sutured by end-to-end anastomosis (Gramegna and others 2003, Soundappan and Barker 2004). In many cases, the retrocaval segment of the right ureter is stenotic or hypoplastic and must be resected (Kakanou and others 2001). Severe hydronephrosis requires nephrectomy (Soundappan and Barker 2004). This short communication describes a rare case of retrocaval ureter in a cat. During routine dissection for educational purposes at the Department of Morphology, Faculty of Veterinary Medicine, Ghent University, a retrocaval ureter was found in an adult, entire male cat (Fig 1). The anomaly was characterised by a medial deviation of the right ureter, which crossed the caudal vena cava dorsally at the level of the fifth lumbar vertebra. The right ureter subsequently emerged between the caudal vena cava and the abdominal aorta, and coursed back in a lateral direction across the ventral surface of the caudal vena cava. It resumed its normal anatomical location along the psoas musculature, and continued caudally towards the urinary bladder. Neither a dilation of the proximal part of the right ureter nor apparent signs of urinary tract inflammation were present. The animal was thoroughly checked for other urogenital, skeletal and cardiovascular congenital malformations, but none was found. No antemortem clinical information was available for the animal. b