Focused ion beam-SEM 3D study of osteodentin in the teeth of the Atlantic wolfish Anarhichas lupus.

The palette of mineralized tissues in fish is wide, and this is particularly apparent in fish dentin. While the teeth of all vertebrates except fish contain a single dentinal tissue type, called orthodentin, dentin in the teeth of fish can be one of several different tissue types. The most common dentin type in fish is orthodentin. Orthodentin is characterized by several key structural features that are fundamentally different from those of bone and from those of osteodentin. Osteodentin, the second-most common dentin type in fish (based on the tiny fraction of fish species out of ∼30,000 extant fish species in which tooth structure was so far studied), is found in most Selachians (sharks and rays) as well as in several teleost species, and is structurally different from orthodentin. Here we examine the hypothesis that osteodentin is similar to anosteocytic bone tissue in terms of its micro- and nano-structure. We use Focused Ion Beam-Scanning Electron Microscopy (FIB/SEM), as well as several other high-resolution imaging techniques, to characterize the 3D architecture of the three main components of osteodentin (denteons, inter-denteonal matrix, and the transition zone between them). We show that the matrix of osteodentin, although acellular, is extremely similar to mammalian osteonal bone matrix, both in general morphology and in the three-dimensional nano-arrangement of its mineralized collagen fibrils. We also document the presence of a complex network of nano-channels, similar to such networks recently described in bone. Finally, we document the presence of strings of hyper-mineralized small 'pearls' which surround the denteonal canals, and characterize their structure.

The 3D organization of the mineralized scales of the sturgeon has structures reminiscent of dentin and bone: A FIB-SEM study.

Scales are structures composed of mineralized collagen fibrils embedded in the skin of fish. Here we investigate structures contributing to the bulk of the scale material of the sturgeon (Acipencer guldenstatii) at the millimeter, micrometer and nanometer length scales. Polished and fracture surfaces were prepared in each of the three anatomic planes for imaging with light and electron microscopy, as well as focused ion beam - scanning electron microscopy (FIB-SEM). The scale is composed of three layers, upper and lower layers forming the bulk of the scale, as well as a thin surface layer. FTIR shows that the scale is composed mainly of collagen and carbonated hydroxyapatite. Lacunae are present throughout the structure. Fracture surfaces of all three layers are characterized by large diameter collagen fibril bundles (CFBs) emanating from a plane comprising smaller diameter CFBs orientated in different directions. Fine lineations seen in polished surfaces of both major layers are used to define planes called here the striation planes. FIB-SEM image stacks of the upper and lower layers acquired in planes aligned with the striation planes, show that CFBs are oriented in various directions within the striation plane, with larger CFBs emanating from the striation plane. Fibril bundles oriented in different directions in the same plane is reminiscent of a similar organization in orthodentin. The large collagen fibril bundles emanating out of this plane are analogous to von Korff fibrils found in developing dentin with respect to size and orientation. Scales of the sturgeon are unusual in that their mineralized collagen fibril organization contains structural elements of both dentin and bone. The sturgeon scale may be an example of an early evolved mineralized material which is neither bone nor dentin but contains characteristics of both materials, however, the fossil data required to confirm this is missing.

Effect of Perineal Urethrostomy on the Length of the Urethra of the Cat: A Cadaveric Study.

Perineal urethrostomy in cats is indicated for urethral pathologies located distal to the bulbourethral glands. The description of the bulbourethral glands as the cranial landmark when performing a PU is based on the increased urethral diameter at this location, rather than on an anatomical limitation. This suggests that urethral pathologies cranial to the bulbourethral glands could potentially be treated with PU. At present, the extent to which the pelvic urethra can be mobilized is unknown. Characterization and quantification of the effect of PU on the pelvic urethra is required prior to attempting to define the location of the pelvic urethra, cranial to the bulbourethral glands, which can be exteriorized when performing a PU. Our aim was to characterize and quantify the effect of performing a PU on the location and length of the pelvic urethra. METHODS: Ten male feline cadavers were used, and four markers were placed on the pelvic urethra via a ventral approach to the peritoneal and pelvic cavities. Two orthogonal radiographic views were acquired prior and subsequent to performing a PU. The distance of each marker to a predefined landmark/origin and the distances of the markers relative to each other were measured on all radiographs. RESULTS: PU resulted in significant caudal translation of the markers relative to the predefined landmark on all radiographic views; however, PU did not result in a significant change in the distances between the markers. CONCLUSIONS: Performing a PU results in caudal translation and minimal stretching of the mobilized pelvic urethra.

Therapeutic efficacy and pharmacokinetics of liposomal-cannabidiol injection: a pilot clinical study in dogs with naturally-occurring osteoarthritis.

Introduction: Osteoarthritis is a common disease in dogs resulting in chronic pain and decreased wellbeing. Common analgesics such as non-steroidal anti-inflammatories may fail to control pain and can produce major adverse effects. Study objectives were to evaluate pharmacokinetics, therapeutic efficacy, and safety of subcutaneous liposomal-cannabidiol (CBD) as an additional analgesic therapy in dogs suffering from naturally-occurring osteoarthritis. Methods: Six such dogs were recruited following ethics approval and owner consent. Dogs were administered a single subcutaneous injection of 5 mg/kg liposomal-CBD. Plasma concentrations of CBD, blood work, activity monitoring collar data, wellbeing questionnaire (owners) and pain scoring (veterinarian) were performed at baseline and monitored up to six weeks following intervention. Data overtime were compared with baseline using linear-regression mixed-effects. P-value was set at 0.05. Results: CBD plasma concentrations were observed for 6 weeks; median (range) peak plasma concentration (Cmax) was 45.2 (17.8-72.5) ng/mL, time to Cmax was 4 (2-14) days and half-life was 12.4 (7.7-42.6) days. Median (range) collar activity score was significantly increased on weeks 5-6; from 29 (17-34) to 34 (21-38). Scores of wellbeing and pain evaluations were significantly improved at 2-3 weeks; from 69 (52-78) to 53.5 (41-68), and from 7.5 (6-8) to 5.5 (5-7), respectively. The main adverse effect was minor local swelling for several days in 5/6 dogs. Conclusion: Liposomal-CBD administered subcutaneously produced detectable CBD plasma concentrations for 6 weeks with minimal side effects and demonstrated reduced pain and increased wellbeing as part of multimodal pain management in dogs suffering from osteoarthritis. Further placebo-controlled studies are of interest.

Determination of Isometric Points in the Stifle of a Dog Using a 3D Model.

OBJECTIVE: The aim of this study was to develop a three-dimensional (3D) model to identify the isometric component of the cranial cruciate ligament (CCL) in dogs. METHODS: A static 3D model of the specimen was generated from a computed tomography scan of the stifle of a dog and a kinematic model was generated from data collected, every 5 degrees from full extension (131 degrees) through 80 degrees of stifle flexion, from four sensors attached to the tibia. Kinematic data were superimposed on the static model by aligning the points of interest, which were defined for both models. This allowed the tibia to rotate and translate relative to the femur based on the kinematic data. The contours of the distal femur and proximal tibia were converted into point clouds and the distance between each point in the femoral point cloud and all the points in the tibial point cloud were measured at each of the 15 positions. The difference between the maximum and minimum distances for each pair of points was calculated, and when it was less than 0.2 mm, points were illustrated as two red dots connected by a line at their locations on the femur and tibia. RESULTS: A total of 3,681 pairs of isometric points were identified and were located at the origin and insertion of the CCL and on the lateral aspect of the stifle. CONCLUSION: Isometric areas are present at the origin and insertion of the CCL and lateral aspect of the stifle. Better understanding of these locations may lead to refinements in techniques to replace the ruptured CCL.

The effect of joint orientation on passive movement of the dog's stifle.

Introduction: The cranial cruciate ligament (CCL) is one of numerous structures which determine the path of the tibia relative to the femur when passively flexing/extending the stifle of the dog. The effect of cutting the CCL on passive motion with the hind limb in different orientations, is unknown. The aim of this study was to describe passive movement of the tibia relative to the femur in dogs, with the hind limb in three different orientations, and with CCL intact and cut. Methods: Ten cadaveric hind limbs were obtained from dogs weighing between 20 kg and 25 kg and prepared for testing in a custom-built joint testing machine. Each hind limb was tested in three different orientations with data collected, using an electromagnetic tracking system, during 2 cycles of flexion/extension with the CCL intact and cut. Each cycle was initiated with the stifle in full extension (0°) and data was collected at 0°, 20°, 30°, 40°, 45°, and 55° of stifle flexion/extension. Results: Flexion of the stifle resulted in caudal translation and internal rotation of the tibia relative to the femur, with cranial translation and external rotation occurring during extension along the identical path. Cutting the cranial cruciate ligament did not result in significant differences in translation or rotation when the stifle was orientated to approximated the standing position of a dog. Discussion: Isometric points at the origin and insertion of the CCL can potentially be identified in CCL deficient stifles using a technique based on passive motion of an intact stifle.

Show Me Your Teeth And I Will Tell You What You Eat: Differences in Tooth Enamel in Snakes with Different Diets.

Teeth are composed of the hardest tissues in the vertebrate body and have been studied extensively to infer diet in vertebrates. The morphology and structure of enamel is thought to reflect feeding ecology. Snakes have a diversified diet, some species feed on armored lizards, others on soft invertebrates. Yet, little is known about how tooth enamel, and specifically its thickness, is impacted by diet. In this study, we first describe the different patterns of enamel distribution and thickness in snakes. Then, we investigate the link between prey hardness and enamel thickness and morphology by comparing the dentary teeth of 63 species of snakes. We observed that the enamel is deposited asymmetrically at the antero-labial side of the tooth. Both enamel coverage and thickness vary a lot in snakes, from species with thin enamel, only at the tip of the tooth to a full facet covered with enamel. There variations are related with prey hardness: snakes feeding on hard prey have a thicker enamel and a lager enamel coverage while species. Snakes feeding on softer prey have a thin enamel layer confined to the tip of the tooth.

Armed to the teeth: The underestimated diversity in tooth shape in snakes and its relation to feeding behavior and diet.

The structure, composition, and shape of teeth have been related to dietary specialization in many vertebrate species, but comparative studies on snakes' teeth are lacking. Yet, snakes have diverse dietary habits that may impact the shape of their teeth. We hypothesize that prey properties, such as hardness and shape, as well as feeding behavior, such as aquatic or arboreal predation, or holding vigorous prey, impose constraints on the evolution of tooth shape in snakes. We compared the morphology of the dentary teeth of 63 species that cover the phylogenetic and dietary diversity of snakes, using 3D geometric morphometrics and linear measurements. Our results show that prey hardness, foraging substrate, and the main feeding mechanical challenge are important drivers of tooth shape, size, and curvature. Overall, long, slender, curved teeth with a thin layer of hard tissue are observed in species that need to maintain a grip on their prey. Short, stout, less curved teeth are associated with species that undergo high or repeated loads. Our study demonstrates the diversity of tooth morphology in snakes and the need to investigate its underlying functional implications to better understand the evolution of teeth in vertebrates.

The use of subchondral bone topography to approximate the center of rotation of the elbow joint in dogs.

OBJECTIVES: The aim of this study was to compare the approximate center of rotation in normal and diseased elbows in dogs. STUDY DESIGN: Cross-sectional study SAMPLE POPULATION: Computer tomography scans of nine dogs with unilateral fragmented medial coronoid process (FMCP). METHODS: A board certified radiologist confirmed that each dog had unilateral FMCP, and a normal contralateral elbow. Digital 3D models of all elbow joints were uploaded into a surgical planning software package. Four axes approximating the center of rotation (COR) of elbow joints were generated using five geometric shapes based on subchondral topography of the humeral condyle radius and ulna. Images showing the locations where axes exited the medial and lateral cortex of the humeral condyle were captured and imported into a second software package, for measurement of distances between exit points and the origin of a system of axes. RESULTS: In normal joints 20/27 (74%) axes exited the medial cortex, and 25/27 (93%) axes exited the lateral cortex cranial and distal to the medial and lateral epicondyles, respectively. In diseased joints 22/27 (81%) axes exited medial cortex and 19/27 (70%) axes exited the lateral cortex, caudal and distal to the medial and lateral epicondyles, respectively. CONCLUSION: Based on CT- derived geometry, the COR of elbow affected with FMCP was generally more caudal than normal. CLINICAL SIGNIFICANCE: External landmarks approximating the location of the elbow COR are provided, and while not validated, may assist in planning, creation, and assessment of procedures for FMCP.

The gelatinases, matrix metalloproteinases 2 and 9, play individual roles in skeleton development.

The gelatinases, a subgroup of the matrix metalloproteinases (MMPs) superfamily are composed of two members; MMP2 and MMP9. They are known to degrade gelatin among other components of the extracellular matrix. Recently, the two gelatinases were found to be necessary for neural crest cell migration and to compensate for each other loss in these cells. To characterize their involvement in the skeletal system, and to better reveal their individual or common roles, we have generated double knockout (dKO) mice, lacking both MMP2 and MMP9. Comprehensive analysis of the skeleton morphological and mechanical parameters at postnatal day (P) 0, P21, 3 months (M) and 8M of age, revealed an unexpected distinct role for each gelatinase; MMP2 was found to be involved merely in intramembranous ossification which led to a smaller skull and inferior cortical parameters upon its loss, while MMP9 was found to affect only the endochondral ossification process, which led to shorter long-bones in its absence. Importantly, the dKO mice demonstrated a combination of both the skull and long bone phenotypes as found in the single-KOs, and not a severer additive phenotype. Transcriptome analysis on the cortical bone, the growth plate and the skull frontal bone, found many genes that were differentially expressed as a direct or indirect result of MMP-loss, and reinforced the specific and distinct role of each gelatinase in each bone type. Altogether, these results suggest that although both gelatinases share the same substrates and are highly expressed in flat and long bones, they are indispensable and control separately the development of different bones.

A rare case of a double vagina in a young American Staffordshire Terrier bitch (Canis lupus familiaris). A case report.

The presence of congenital urogenital malformations is relatively common in bitches. However, cases of double vagina in the literature are scarce, and the ones reported usually accompany other urogenital defects. The vaginal anomaly was an incidental finding in the present case during a routine spay and was not accompanied by any other malformations. A detailed presentation of the diagnosis and surgical management of the double vagina is presented in the current paper. A 1-year-old nulliparous American Staffordshire Terrier bitch was presented for dysuria in the past 24 h. After inspection and palpation, a distended abdomen was noticed. Biochemistry, hematology, and urinalysis were performed. No other laboratory findings were noted besides mild hypocalcemia, hypoproteinemia, hypobilirubinemia, and increased lipase. During the ultrasonographic examination, a hypoechoic fluid accumulation was observed caudal to the urinary bladder in what seemed to be hydrocolpos. Exploratory laparotomy was recommended. Ovariohysterovaginectomy was performed, and the gross and histological findings were highly suggestive of a double vagina. The dog recovered from surgery uneventfully, and it was free of clinical signs six months after the surgery. To the extent of our knowledge, this is the first case of double vagina, without any other congenital defects, ultrasonography documented and surgically corrected, in a young bitch.

Modified Tibial Tuberosity Advancement Rapid in a Dog with One Contralateral Amputated Limb.

Cranial cruciate ligament disease (CCLD) is one of the most frequent causes of hindlimb lameness in dogs. Tibial tuberosity advancement (TTA) is a common surgery performed for CCLD. A modified, simplified technique (TTA Rapid) is also reported to have very good clinical outcomes. In this paper, we report a modified TTA Rapid technique to treat a CCLD in a dog with an amputated contralateral hindlimb. A 5-year-old mixed breed dog presented with amputated right hindlimb and difficulty walking. Pain and positive drawer sign were present at manipulation of left stifle joint. Radiographic findings of the stifle joint confirmed the presence of moderate osteoarthritis associated with CCLD, and modified TTA Rapid procedure was performed. Recovery from surgery was uneventful, and the dog was able to stand by his own by the second day postoperative. At three months follow-up evaluation, the dog was free of lameness and the osteotomy site was completely healed. This paper describes the first modified TTA rapid osteotomy technique performed in a dog with a contralateral amputated hindlimb.

The Effect of Increasing Tibial Tuberosity Advancement and Quadriceps Muscle Force on Cranial Translation of the Tibia in the Cranial Cruciate Deficient Stifle Joint in Dogs.

Background: Cranial cruciate ligament (CCL) disease is a well-known pathology that generates both rotational and translational instability of the stifle joint that leads to osteoarthritis in dogs. Tibial tuberosity advancement (TTA) is a common surgical technique used to dynamically neutralize the tibiofemoral shear forces to achieve stifle joint stability. However, significant persistent instability has been documented in clinical cases. The purpose of this study was to evaluate the effect of increasing quadriceps load, increasing tibial tuberosity advancement, and increasing joint flexion angle on the cranial translation of the tibia relative to the femur in the cranial cruciate ligament deficient stifle joint. Methods and Results: Six cadaveric hind limbs were collected from six healthy mixed breed dogs of medium build and prepared for biomechanical testing. The specimen was placed into a custom-made joint testing machine, and translation of the tibia relative to the femur was measured at stifle angles of 135°, 120°, and 105°. Cranial tibial thrust was generated by applying a vertical load to the metatarsal pad and the quadriceps muscle was simulated with loads of 0, 5, and 10 kg applied to the patella via a system of weights and pulleys. All specimens were tested with the CCL intact and cut, both of which served as controls. The tibial tuberosity was then advanced using both 6 mm and 9 mm cages, and the specimen was tested using the identical technique. Each specimen was loaded to failure by increasing the load applied to the pes until the sudden marked cranial translation of the tibia. Tibial tuberosity advancement with an applied quadriceps load was successful in limiting cranial tibial translation in 54/62 tests. Under similar loading conditions, TTA failed to limit cranial translation in 8 tests. The failures occurred at all angles of flexion examined. In the cases that failed cranial translation could be limited by either increasing the quadriceps load or increasing the amount of tibial tuberosity advancement. Conclusion: This study showed that TTA with an applied quadriceps load is effective at decreasing cranial tibial translation at functional joint angles.

Coxofemoral luxation as a complication of localised tetanus in a cat.

Case summary: A 9-month-old male neutered domestic shorthair cat presented 2 weeks after castration with a 48 h history of acute-onset lateral recumbency and severe hindlimb rigidity. Physical examination findings included hyperthermia, tachypnoea, hindlimb rigidity and a healed orchidectomy site. Neurological examination of the head and forelimbs was normal; however, there was a spastic, non-ambulatory paraparesis of the hindlimbs, which was more severe on the left. Abnormal findings included mildly elevated serum creatine kinase levels and on electromyography there was bilateral pathological spontaneous activity of the biceps femoris muscles. A tentative diagnosis of tetanus was made based on clinical presentation. Treatment was initiated with tetanus antitoxin, diazepam, metronidazole, buprenorphine and physiotherapy of the hindlimbs. There was an improvement over the following 20 days. Twenty-five days later the cat presented with acute, painful, non-weightbearing lameness of the left hindlimb. Physical examination was suggestive of craniodorsal coxofemoral joint luxation, which was confirmed radiographically. This was treated with analgesia and rest. A marked clinical improvement was observed at the 3-month follow-up. Relevance and novel information: To our knowledge, there have been no previously published reports of spontaneous coxofemoral joint luxation as a complication of hindlimb localised tetanus infection in cats. This report suggests that coxofemoral luxation should be considered as a possible complication in young cats with hindlimb localised tetanus.

Osteodentin in the Atlantic wolffish (Anarhichas lupus): Dentin or bone?

The teeth of actinopterygian fish, like those of mammals, consist of a thin outer hyper-mineralized layer (enamel or enameloid) that surrounds a core of dentin. While all mammalian species have a single type of dentin (called orthodentin), various dentin types have been reported in the teeth of actinopterygian fish. The most common type of actinopterygian fish dentin is orthodentin. However, the second most common type of actinopterygian fish dentin, called osteodentin, found in several teleost species and in many Selachians, is structurally radically different from orthodentin. Osteodentin, comprising denteons and inter-denteonal matrix, is characterized by an appearance that is similar to mammalian osteonal bone, however, it lacks cells and a lacuno-canalicular system. The current consensus is that although osteodentin is morphologically different from orthodentin, it is a true dentinal material, the product of odontoblast cells. We present the results of a study of osteodentin found in the teeth of the Atlantic wolffish, Anarhichas lupus. Using a variety of microscopy techniques, high-resolution microCT scans, and micro-indentation we describe the three-dimensional structure of both its components (denteons and inter-denteonal matrix), as well as their mineral density distribution and mechanical properties, at several length-scales. We show that wolffish osteodentin is remarkably similar to the anosteocytic bone of the swords of several swordfish species. We also describe the three-dimensional network of canals found in mature osteodentin. The high density of these canals in a metabolically inactive, acellular tissue casts doubt upon the accepted paradigm, that the canals house a vascular network.

The Use of Sixty Degree Rotation of the Acetabulum for Treatment of Dogs With Canine Hip Dysplasia. A Short Case Series.

Triple pelvic osteotomy (TPO) is a prophylactic surgical procedure performed on dogs with canine hip dysplasia. The procedure is indicated in skeletally immature dogs without secondary osteoarthritis (OA). It has been suggested that 60° of rotation is excessive and is associated with poor outcome. The objective of the study was to assess the medium term outcome in dogs having undergone triple pelvic osteotomy (TPO) using 60° dedicated plates. Nine TPOs were performed in seven dogs with hip dysplasia. Eight of nine hips had 72-100% osseous union at the time of revisit. The mean time to final radiographic recheck was 200 days (range, 185-229 days). The mean time to follow-up was 11.5 months (range 11-12 months). All 7 dogs had regained full function and did not require supplemental analgesia. Pelvic canal narrowing was noted in the two dogs with bilateral surgeries, but no clinical consequences were noted according to owner's statement.If more than 40 degrees reduction angles at Ortolani test, 60° of rotation of the acetabulum can be used successfully in dogs with hip dysplasia. At the time of mid-term follow-up, all dogs in this case series had full function.

The effect of the interosseous ligament and selected antebrachiocarpal ligaments on rotation of the radius during extension of the carpus.

OBJECTIVE: To evaluate the effect of the interosseous ligament and selected antebrachiocarpal ligaments on the internal rotation of the radius relative to the ulna, during carpal extension. STUDY DESIGN: Cadaveric study. SAMPLE POPULATION: Twenty-four cadaveric canine forelimbs. METHODS: Twenty-four forelimbs were disarticulated at the elbow joint and the antebrachia were prepared for testing. The forelimbs were divided to 6 groups, defined by the order in which ligaments were transected. All specimens were tested intact and after transecting each of the ligaments with the order defined by the group. Rotation of the radius relative to the ulna, caused by extension of the carpus, was measured using a sensor connected to the radius. RESULTS: The mean(±sd) maximum internal rotation of the radius (5.94° ± (1.23°)) with all the ligaments intact was significantly greater (p < 0.012) than the mean(±sd) maximum internal rotation of the radius (3.13° (± 1.13°)) after transecting the interosseus ligament. Transecting the interosseous ligament subsequent to one of the other ligaments caused a decrease in internal radial rotation (p = 0.629), while, transecting the short radial collateral ligament caused an increase in radial rotation (p = 0.629). Transecting the palmar radiocarpal and ulnocarpal ligaments had no effect on radial rotation. CONCLUSION: The interosseous ligament was stretched with internal rotation of the radius due to carpal extension. Carpal flexion resulted in external rotation of the radius. This effect was lost when the interosseus ligament was transected. CLINICAL SIGNIFICANCE: Rotation of the radius is associated with carpal extension, and is likely an intrinsic part of forelimb biomechanics.

Force Distribution in the Canine Proximal Radio-Ulnar Joint on Extension of the Carpal Joint: A Cadaveric Study.

OBJECTIVE: The aim of this study was to measure the load on the lateral and medial aspects of the proximal radio-ulnar joint during extension of the carpus. STUDY DESIGN: This was an ex vivo biomechanical study. SAMPLE POPULATION: Twenty-two cadaveric Greyhound thoracic limbs were used. METHODS: Twenty-two paired thoracic limbs were used. The olecranon was attached to a custom jig with the foot resting on a stationary anvil. Load sensors were inserted into the proximal radio-ulnar joint, between the radial head and the lateral coronoid process, and between the radial head and the medial coronoid process. Specimens were tested under compression with measurements taken at 0, 4, 9 and 13.5 mm of axial displacement. Data collected at each point included forces on the specimen and medial and lateral coronoid processes as well as the angle of carpal joint extension. RESULTS: A linear mixed effects model relating load on the specimen and carpal joint extension angle had an R-squared value of 0.66, and load at the level of the medial coronoid process and angle of carpal extension had an R-squared value of 0.61. There was a significant difference in the loads measured on the lateral and medial coronoid processes at all angles (p < 0.0001). CONCLUSION: Extension of the carpus results in asymmetric loading of the proximal radio-ulnar joint. CLINICAL SIGNIFICANCE: The findings of this study show that loading of the medial coronoid process may be more complex than originally thought and supports the future investigation of novel management and therapeutic options for affected patients.

Use of bilateral superficial gluteal muscle flaps for the repair of ventral perineal hernia in dogs: A cadaveric study and short case series.

OBJECTIVE: To describe bilateral mobilization of the superficial gluteal muscle (SGM) to treat ventral perineal hernias in dogs. STUDY DESIGN: Cadaveric study and short case series. SAMPLE POPULATION: Male dog cadavers (n = 10) weighing between 5 and 42 kg and three dogs treated for ventral perineal hernia. METHODS: Cadavers were positioned in right and left lateral recumbency to free the origin and insertion of the ipsilateral SGM except for muscle fibers originating on the first tail vertebra and sacrotuberous ligament. The dogs were placed in ventral recumbency to approach the perineum and rotate the muscle flaps. The insertions of the SGM were sutured together ventral to the anal sphincter muscle. The dorsal border of the overlapping tendons was sutured to the anal sphincter muscle, and the ventral border was sutured to the ischiourethralis muscle. The amount of overlap between bilateral flaps was measured. The SGM flaps were used to revise recurrent perineal hernias in three dogs. RESULTS: Superficial gluteal muscle flaps were created without damage to the blood supply in all dogs. The overlap between the bilateral flaps ventral to the anal sphincter measured 0 to 2.4 cm. No recurrence was detected at follow-up (6-12 months) in the three dogs treated with these flaps. CONCLUSION: Superficial gluteal muscle flaps were mobilized without damage to the blood supply and crossed the midline ventral to the anal sphincter. Flaps were used successfully to repair ventral perineal hernias in three dogs. CLINICAL SIGNIFICANCE: Bilateral SGM flaps can be considered to repair ventral perineal hernias.

Small vs. Large Suture Bite-to-Stitch Interval for Closure of Midline Celiotomy in Cats: A Biomechanical Study.

Objective: The objective of this study was to compare the bursting strength and characterize the mode of failure of cranial and caudal midline celiotomies closed with 2 suture patterns and an absorbable monofilament suture material. Design: Randomized, cadaveric, ex- vivo mechanical testing. Sample: Feline cadavers (n = 32). Methods: Specimens were randomized into two groups based on the closure technique (small 2 × 2 mm or large 5 × 5 mm suture-bite-stitch-interval [SBSI] groups). Cranial or caudal midline celiotomies, 7.5 cm long, were created. A custom-made polyurethane bladder was inserted into the abdomen, and the celiotomies were closed in a simple continuous pattern using 3-0 polydioxanone. The repair was loaded to failure by inflating the bladder with compressed air. Bursting strength and mode of failure were recorded. Effects of body weight, gender, thickness and width of linea alba, suture-bite-stitch-interval, and location of celiotomy were analyzed using a mixed model analysis and an independent t- test, with P < 0.05 considered statistically significant. Results: There was no difference in bursting strength between cranial and caudal celiotomies. Bursting strength was lower for celiotomies closed with a large SBSI (P = 0.003). Bursting strength was greater in males compared to females (P = 0.003). Twenty five specimens failed distant from celiotomy closure, while 4 failed by fascial tearing at the site of needle penetration. Failure by loosening of the suture line with intact knots only occurred in 3 caudal celiotomies closed with a large SBSI. Gender, body weight and SBSI accounted for 61.5% of variability in bursting strength (P = 0.005). Conclusions: Small SBSI technique was mechanically superior to large SBSI when tested under these loading conditions. Clinical relevance: Supraphysiological pressures were required to cause failure in all specimens. Both small and large SBSI may be clinically applicable for midline celiotomy closure in domestic cats.