Evaluation of functional muscle anatomy scalability in the canine hind limb.

In contrast to other mammals, the large variation in dog sizes is not accompanied by any significant genetic re-organization. In order to study the relationship between body mass, limb length and the functional anatomical muscle parameters of the canine hind limb, a large dataset comprising of muscle masses, optimal muscle fibre lengths and physiological cross-sectional area's (PCSA) were acquired for twenty-five muscles in ten dogs of sizes varying between 20 kg and 52 kg. The potential of body mass and limb length for reliably scaling individual muscle masses, optimal muscle fibre lengths and PCSA's were examined. For the majority of the muscles of the canine hind limb, neither body mass nor limb length were reliable scaling parameter for either muscle masses, PCSA's and optimal fibre length. These results indicate the need of a breed-specific approach to musculoskeletal modelling in future canine musculoskeletal research.

Spatial Subchondral Bone Density Reflecting Joint Loading of the Talus in Different Canidae.

OBJECTIVE: Subchondral bone density distribution can be used to study joint biomechanics non-invasively. Differences in joint loading between related species can aid in the understanding of joint loading and the development of certain types of orthopaedic pathology. This study was conducted to evaluate density distribution in the subchondral bone of the talus of different Canidae species, as a parameter reflecting the long-term joint loading in the tarsocrural joint. MATERIALS AND METHODS: The tarsal joints of cadaveric dogs of different breeds were included, that is, German Shepherd (n = 5), Bouvier des Flandres (n = 3) and Labrador Retriever (n = 6).Additionally, golden jackals (n = 5) (Canis aureus) and wolves (n = 5) (Canis lupus) were included. Consecutive computed tomography slices were made and the subchondral bone density distribution was evaluated using computer tomographic osteoabsorptiometry. Different breeds and species were visually compared. RESULTS: Differences were found in the subchondral bone density distribution of the talus between breeds and between species (Canis familiaris, Canis lupus and Canis aureus). DISCUSSION AND CONCLUSION: Based on the density distribution, there are differences in loading conditions of the tarsocrural joint in different species of Canidae. The joint loading distribution is very similar between dogs of the same breed and within the same species. Although between-breed differences can be explained by conformational differences, the between-species differences remain subject to further research.

Musculoskeletal modelling in dogs: challenges and future perspectives.

Musculoskeletal models have proven to be a valuable tool in human orthopaedics research. Recently, veterinary research started taking an interest in the computer modelling approach to understand the forces acting upon the canine musculoskeletal system. While many of the methods employed in human musculoskeletal models can applied to canine musculoskeletal models, not all techniques are applicable. This review summarizes the important parameters necessary for modelling, as well as the techniques employed in human musculoskeletal models and the limitations in transferring techniques to canine modelling research. The major challenges in future canine modelling research are likely to centre around devising alternative techniques for obtaining maximal voluntary contractions, as well as finding scaling factors to adapt a generalized canine musculoskeletal model to represent specific breeds and subjects.

An heuristic filtering tool to identify phenotype-associated genetic variants applied to human intellectual disability and canine coat colors.

BACKGROUND: Identification of one or several disease causing variant(s) from the large collection of variants present in an individual is often achieved by the sequential use of heuristic filters. The recent development of whole exome sequencing enrichment designs for several non-model species created the need for a species-independent, fast and versatile analysis tool, capable of tackling a wide variety of standard and more complex inheritance models. With this aim, we developed "Mendelian", an R-package that can be used for heuristic variant filtering. RESULTS: The R-package Mendelian offers fast and convenient filters to analyze putative variants for both recessive and dominant models of inheritance, with variable degrees of penetrance and detectance. Analysis of trios is supported. Filtering against variant databases and annotation of variants is also included. This package is not species specific and supports parallel computation. We validated this package by reanalyzing data from a whole exome sequencing experiment on intellectual disability in humans. In a second example, we identified the mutations responsible for coat color in the dog. This is the first example of whole exome sequencing without prior mapping in the dog. CONCLUSION: We developed an R-package that enables the identification of disease-causing variants from the long list of variants called in sequencing experiments. The software and a detailed manual are available at https://github.com/BartBroeckx/Mendelian.

Computed Tomographic and Low-Field Magnetic Resonance Arthrography: A Comparison of Techniques For Observing Intra-articular Structures of the Normal Canine Shoulder.

OBJECTIVE: To compare low-field magnetic resonance arthrography (MRA) and computed tomographic arthrography (CTA) for identification of intra-articular ligaments and joint cartilage in the normal canine shoulder with the aid of cross-sectional anatomy. ANIMALS: Normal adult Foxhounds (n = 3) and 4 Foxhound cadaver shoulders. METHODS: CTA of 3 dogs was performed after intra-articular administration of contrast medium in both shoulders. Transverse slices and reformatted sagittal and dorsal images were obtained. Later, an MRA study of all 6 shoulder joints was performed using a low-field system. T1- and T2-weighted images were made in 3 planes, arthrography performed, and T1-weighted images repeated. Unrelated cadaver shoulder joints were injected with red methylmethacrylate, frozen, and sectioned into dorsal, sagittal, and transverse sections. Representative anatomic images were compared with the CTA, MRA, and T2-weighted images. RESULTS: The joint cartilage was identified on all CTA images. The glenohumeral ligaments were clearly visible on the transverse and dorsal CTA and MRA images but were not detected on the T2-weighted sequences. The biceps tendon could be evaluated on all images. The supraspinatus, infraspinatus, and subscapularis muscle tendons were most easily identified on the MRA and T2-weighted MR images. CONCLUSIONS: CTA was useful for seeing articular cartilage and both CTA and MRA were useful for seeing the normal glenohumeral ligaments; however, further research is needed to examine each technique's sensitivity for diagnosing the pathology of these ligaments and any associated lesions of the capsule, tendon, and bone, and for determining the clinical importance of CTA for evaluating loose fragments or osteochondral lesions.

Comparison of clinical and computed tomographic features between medial and lateral trochlear ridge talar osteochondrosis in dogs.

OBJECTIVE: To evaluate clinical and subchondral bone lesion differences between medial (MTRT-OC) and lateral trochlear ridge tarsocrural osteochondrosis (LTRT-OC). STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 66) with MTRT-OC or LTRT-OC. METHODS: Medical records (1997-2010) of dogs with MTRT-OC or LTRT-OC were reviewed. Clinical data (breed, age, gender, weight, and duration of clinical signs) were retrieved. Computed tomographic examinations of the tarsocrural joints were performed. Length, width, and depth of the subchondral bone lesions on the computed tomographic images, and surface and volume of the lesions were estimated. The location of the OC lesion on the trochlear ridge (proximal, dorsal, or distal) was determined. Data collected from dogs with MTRT-OC (n = 56) were compared with data from dogs with LTRT-OC (n = 10). RESULTS: Length, width, depth, surface, and volume of LTRT-OC lesions were significantly (P < .01) larger than those of MTRT-OC lesions. Dogs with LTRT-OC were significantly younger at the time of diagnosis (P < .01). CONCLUSIONS: OC lesions on the lateral trochlear ridge are significantly larger than those on the medial trochlear ridge. Dogs with lesions on the lateral trochlear ridge are significantly younger at the time of diagnosis, and tend to have a shorter duration of lameness before presentation.