The early development of medial coronoid disease in growing Labrador retrievers: radiographic, computed tomographic, necropsy and micro-computed tomographic findings

Medial coronoid disease (MCD) encompasses lesions of the entire medial coronoid process (MCP), both of the articular cartilage and the subchondral bone. To detect the earliest signs of MCD, radiography and computed tomography were used to monitor the development of MCD in 14 Labrador retrievers, from 6 to 7 weeks of age until euthanasia. The definitive diagnosis of MCD was based on necropsy and micro-computed tomography findings. The frequency of MCD in the dogs studied was 50%. Radiographic findings did not provide evidence of MCD, ulnar subtrochlear sclerosis or blunting of the cranial edge of the MCP. Computed tomography was more sensitive (30.8%) than radiography (0%) in detecting early MCD, with the earliest signs detectable at 14 weeks of age. A combination of the necropsy and micro-computed tomography findings of the MCP showed that MCD was manifested as a lesion of only the subchondral bone in dogs <18 weeks of age. In all dogs (affected and unaffected), there was close contact between the base of the MCP and the proximal radial head in the congruent joints. Computed tomography and micro-computed tomography findings indicated that the lesions of MCD probably originated at the base of the MCP

Delayed endochondral ossification in early medial coronoid disease (MCD): a morphological and immunohistochemical evaluation in growing Labrador retrievers

Medial coronoid disease (MCD) is a common joint disease of dogs. It has a multifactorial aetiology, but the relationship between known causal factors and the disease has yet to be elucidated. As most of the published literature is clinical and it reports changes associated with advanced disease, it is not known whether the changes reflect the cause or consequences of the condition. The aim of this study was to investigate early micromorphological changes occurring in articular cartilage and to describe the postnatal development of the medial coronoid process (MCP) before MCD develops. Three litters of MCD-prone young Labrador retrievers were purpose-bred from a dam and two sires with MCD. Comparisons of the micromorphological appearance of the MCP in MCD-negative and MCD-positive joints demonstrated that MCD was initially associated with a disturbance of endochondral ossification, namely a delay in the calcification of the calcifying zone, without concurrent abnormalities in the superficial layers of the joint cartilage. Cartilage canals containing patent blood vessels were only detected in dogs <12 weeks old, but the role of these channels in impaired ossification requires further investigation. Retained hyaline cartilage might ossify as the disease progresses, but weak areas can develop into cracks between the retained cartilage and the subchondral bone, leading to cleft formation and fragmentation of the MCP

Functional Locomotor Consequences of Uneven Forefeet for Trot Symmetry in Individual Riding Horses

ABSTRACT: Left-right symmetrical distal limb conformation can be an important prerequisite for a successful performance, and it is often hypothesized that asymmetric or uneven feet are important enhancing factors for the development of lameness. On a population level, it has been demonstrated that uneven footed horses are retiring earlier from elite level competition, but the biomechanical consequences are not yet known. The objectives of this study were to compare the functional locomotor asymmetries of horses with uneven to those with even feet. Hoof kinetics and distal limb kinematics were collected from horses (n = 34) at trot. Dorsal hoof wall angle was used to classify horses as even or uneven (1.5° difference between forefeet respectively) and individual feet as flat (55°). Functional kinetic parameters were compared between even and uneven forefeet using MANOVA followed by ANOVA. The relative influences of differences in hoof angle between the forefeet and of absolute hoof angle on functional parameters were analysed using multiple regression analysis (P<0.05). In horses with uneven feet, the side with the flatter foot showed a significantly larger maximal horizontal braking and vertical ground reaction force, a larger vertical fetlock displacement and a suppler fetlock spring. The foot with a steeper hoof angle was linearly correlated with an earlier braking-propulsion transition. The conformational differences between both forefeet were more important for loading characteristics than the individual foot conformation of each individual horse. The differences in vertical force and braking force between uneven forefeet could imply either an asymmetrical loading pattern without a pathological component or a subclinical lameness as a result of a pathological development in the steeper foot

Comparative analysis of avian hearts provides little evidence for variation among species with acquired endothermy

Mammals and birds acquired high performance hearts and endothermy during their independent evolution from amniotes with many sauropsid features. A literature review shows that the variation in atrial morphology is greater in mammals than in ectothermic sauropsids. We therefore hypothesized that the transition from ectothermy to endothermy was associated with greater variation in cardiac structure. We tested the hypothesis in 14 orders of birds by assessing the variation in 15 cardiac structures by macroscopic inspection and histology, with an emphasis on the atria as they have multiple features that lend themselves to quantification. We found bird hearts to have multiple features in common with ectothermic sauropsids (synapomorphies), such as the presence of three sinus horns. Convergent features were shared with crocodylians and mammals, such as the cranial offset of the left atrioventricular junction. Other convergent features, like the compact organization of the atrial walls, were shared with mammals only. Pacemaker myocardium, identified by Isl1 expression, was anatomically node-like (Mallard), thickened (Chicken), or indistinct (Lesser redpoll, Jackdaw). Some features were distinctly avian, (autapomorphies) including the presence of a left atrial antechamber and the ventral merger of the left and right atrial auricles, which was found in some species of parrots and passerines. Most features, however, exhibited little variation. For instance, there were always three systemic veins and two pulmonary veins, whereas among mammals there are 2-3 and 1-7, respectively. Our findings suggest that the transition to high cardiac performance does not necessarily lead to a greater variation in cardiac structure

Comparative analysis of avian hearts provides little evidence for variation among species with acquired endothermy

Mammals and birds acquired high performance hearts and endothermy during their independent evolution from amniotes with many sauropsid features. A literature review shows that the variation in atrial morphology is greater in mammals than in ectothermic sauropsids. We therefore hypothesized that the transition from ectothermy to endothermy was associated with greater variation in cardiac structure. We tested the hypothesis in 14 orders of birds by assessing the variation in 15 cardiac structures by macroscopic inspection and histology, with an emphasis on the atria as they have multiple features that lend themselves to quantification. We found bird hearts to have multiple features in common with ectothermic sauropsids (synapomorphies), such as the presence of three sinus horns. Convergent features were shared with crocodylians and mammals, such as the cranial offset of the left atrioventricular junction. Other convergent features, like the compact organization of the atrial walls, were shared with mammals only. Pacemaker myocardium, identified by Isl1 expression, was anatomically node-like (Mallard), thickened (Chicken), or indistinct (Lesser redpoll, Jackdaw). Some features were distinctly avian, (autapomorphies) including the presence of a left atrial antechamber and the ventral merger of the left and right atrial auricles, which was found in some species of parrots and passerines. Most features, however, exhibited little variation. For instance, there were always three systemic veins and two pulmonary veins, whereas among mammals there are 2-3 and 1-7, respectively. Our findings suggest that the transition to high cardiac performance does not necessarily lead to a greater variation in cardiac structure

Trabecular bone of precocials at birth; Are they prepared to run for the wolf(f)?

Bone is a dynamic tissue adapting to loading according to "Wolff's law of bone adaptation." During very early life, however, such a mechanism may not be adequate enough to adapt to the dramatic change in environmental challenges in precocial species. Their neonates are required to stand and walk within hours after birth, in contrast to altricial animals that have much more time to adapt from the intrauterine environment to the outside world. In this study, trabecular bone parameters of the talus and sagittal ridge of the tibia from stillborn but full-term precocials (calves and foals) were analyzed by micro-CT imaging in order to identify possible anticipatory mechanisms to loading. Calculated average bone volume fraction in the Shetland pony (49-74%) was significantly higher compared to Warmblood foals (28-51%). Bovine trabecular bone was characterized by a low average bone volume fraction (22-28%), however, more directional anisotropy was found. It is concluded that anticipatory strategies in skeletal development exist in precocial species, which differ per species and are most likely related to anatomical differences in joint geometry and related loading patterns. The underlying regulatory mechanisms are still unknown, but they may be based on a genetic blueprint for the development of bone. More knowledge, both about a possible blueprint and its regulation, will be helpful in understanding developmental bone and joint diseases. J. Morphol., 2016. © 2016 Wiley Periodicals, Inc

Dietary Vitamin D Supplementation during Early Growth is not Protective for Medial Coronoid Disease Development in Labradors

Introduction: Medial coronoid disease (MCD) is a common heritable disease in young large-breed dogs and is characterized by fissures and/or fragmentation of the medial coronoid process (MCP), cartilage, and/or subchondral bone. MCD development has also been attributed to disturbed endochondral ossification. Vitamin D influences skeletal development and endochondral ossification by stimulating the terminal differentiation of chondrocytes and the mineralization of cartilage and the newly formed osteoid. The aim of this study was to investigate whether vitamin D supplementation of the standard puppy diet given to puppies after weaning can prevent the development of medial coronoid disease (MCD) by stimulating endochondral ossification, including terminal differentiation of chondrocytes, and mineralization of the cartilaginous template of the developing medial cornoid process (MCP). Animals, material and methods: A litter of Labrador puppies was on purpose bred by mating a dam and a sire with MCD; these dogs are known to produce offspring with MCD. The puppies received a diet supplemented with 50,000 IU vitamin D per kg as fed. Development of MCD was monitored by computed tomography (CT) and plain radiographs every two weeks, and post-mortem by microCT, necropsy, histology, and immunohistochemistry and compared with data from a previous study. Results and discussion: Vitamin D supplementation did result in increased plasma levels of 25- vitamin D and 1.25-vitamin D, but did not prevent development of MCD in growing Labradors. Instead, vitamin D supplementation resulted in increased collagen X staining ofthe MCP and irregular costal growth plates, demonstrating disturbed endochondral ossification. Conclusion: Vitamin D supplementation does not prevent MCD development. Other causes for MCD rather than relative vitamin D deficiency causing disturbed endochondral ossification are more likely

Dietary Vitamin D Supplementation during Early Growth is not Protective for Medial Coronoid Disease Development in Labradors

Introduction: Medial coronoid disease (MCD) is a common heritable disease in young large-breed dogs and is characterized by fissures and/or fragmentation of the medial coronoid process (MCP), cartilage, and/or subchondral bone. MCD development has also been attributed to disturbed endochondral ossification. Vitamin D influences skeletal development and endochondral ossification by stimulating the terminal differentiation of chondrocytes and the mineralization of cartilage and the newly formed osteoid. The aim of this study was to investigate whether vitamin D supplementation of the standard puppy diet given to puppies after weaning can prevent the development of medial coronoid disease (MCD) by stimulating endochondral ossification, including terminal differentiation of chondrocytes, and mineralization of the cartilaginous template of the developing medial cornoid process (MCP). Animals, material and methods: A litter of Labrador puppies was on purpose bred by mating a dam and a sire with MCD; these dogs are known to produce offspring with MCD. The puppies received a diet supplemented with 50,000 IU vitamin D per kg as fed. Development of MCD was monitored by computed tomography (CT) and plain radiographs every two weeks, and post-mortem by microCT, necropsy, histology, and immunohistochemistry and compared with data from a previous study. Results and discussion: Vitamin D supplementation did result in increased plasma levels of 25- vitamin D and 1.25-vitamin D, but did not prevent development of MCD in growing Labradors. Instead, vitamin D supplementation resulted in increased collagen X staining ofthe MCP and irregular costal growth plates, demonstrating disturbed endochondral ossification. Conclusion: Vitamin D supplementation does not prevent MCD development. Other causes for MCD rather than relative vitamin D deficiency causing disturbed endochondral ossification are more likely

Number of even and uneven footed horses and modified AAEP lameness scores 0/5 trot for walk and for trot separately.

<p>Number of even and uneven footed horses and modified AAEP lameness scores 0/5 trot for walk and for trot separately.</p

Photograph and three-dimensional reconstruction of one uneven footed horse showing the marker set used in the study.

<p>a) A photograph showing the anatomical and tracking markers used for the study. The photograph illustrates the definition of a horse with uneven feet where the right forelimb has a lower hoof angle (LHA) and the left forelimb has a higher hoof angle (HHA). b) An example of the functional consequences of unevenness in one horse with a difference in dorsal hoof wall angle of 8 degrees. Three-dimensional reconstruction of the left and right forelimbs in the position of maximum vertical MCPJ displacement. The blue and yellow circles show the position of the MCPJ and the blue line originating from the centre of the foot is the resultant force vector. The hoof on the left is the lower hoof angle (LHA; blue: RF) and the hoof on the right is the higher hoof angle (HHA; yellow: LF).</p