Morphology of the Canine Stance (2005)

A study was conducted to measure the morphology of dogs while standing. The research accomplished by this project will create a basic database for canine morphology at a stance, including standing joint angles, limb circumferences, and bone lengths for the front and rear limbs. This database represents a variety of dogs of various sizes and breeds. The results indicated that dogs of different sizes have different limb lengths and circumferences, but do not have characteristically larger or smaller joint angles based on their respective size. Introduction: Previous studies have examined various aspects of canine orthopedics, and many studies have focused on specific joints or diseases. Goniometry has been developed to measure range of motion and was used to obtain the data for this study. Research has shown that some breeds and sizes of dogs are more prone to developing joint problems, with large dogs and certain breeds often having a greater risk. It is possible that larger dogs may have different joint angles as compared with smaller dogs, and this may make them more susceptible to certain conditions. However, there may not be a significant difference in the morphology of standing joint angles between small, medium, and large dogs because many factors playa role in joint problems and other differences exist between various breeds of dogs. Previous literature regarding canine orthopedics has provided information for normal standing angles that are used to surgically fuse joints when necessary as a result of severe injury or disease. Some of these can be used to compare to the results found in this study. The angles previously published were: carpus: 1 0-15° (equivalent to the carpal joint angle measured in this study plus 180°),1 stifle: 135-140°,2 and hock: 135145°.3 These angles were recommended for either immobilization of a joint or for fusing ajoint, and are used to compare with our data. The dogs used in this study included beagles, hounds, retrievers, and other large mixedbreed dogs. Individual breeds vary in their conformation because some dogs have different body shapes; for example, bulldogs have a chondrodystrophic body type with angular limb conformation, while others, such as greyhounds, have longer, straighter legs. Therefore, the dogs cannot be compared only by size. In this study, standing angles and range of motion were obtained using a goniometer. Corresponding bone lengths and circumferences of the femur, tibia, metatarsals, humerus, antebrachium (combined radius and ulna) and metacarpals were also measured using a measuring tape. Limb circumference for each bone was determined at 50% of the bone length. Results were obtained from a variety of dog breeds and sizes to provide a broader range for the usefulness of the information obtained. The purpose of this study, then, was to evaluate standing joint angles in dogs to establish standard reference information that can be used in future studies and research. I hypothesized that although there would significant differences in limb length and limb circumference, there would not be a significant difference in the morphology of standing joint angles between small, medium, and large dogs. Experimental Procedure: Since the purpose of this study was to create a standard, measurements were only made on healthy animals. Microsoft Excel was used to record and organize the data, shown in Figure 1. The procedure of measuring a dog began with selecting a side to measure and obtaining basic information of weight, age, and name. If the dog had one abnormal or injured leg, then the opposite normal side was chosen; otherwise, the right side was arbitrarily chosen. (1) Standing Angles The joint angles were recorded while the dog was standing in a normal position as squarely as possible, with each fore and rear limb symmetrically placed. The joints measured included the hip, stifle, hock, shoulder, elbow, and carpus. Figure 2 is a diagram of the angles that were measured. The same landmarks on the bones were used for measuring each time.