Your dog's skeletal system works in conjunction with the muscles, tendons and ligaments, allowing the dog to move freely. When your dog suffers an injury to its shoulder joint or to the adjacent tendons from a jumping impact, muscle strain or a trauma to the joint, it may limp or refuse to put pressure on its front legs.
Unlike humans, dogs have no collarbones connecting to its shoulder blades. The humerus bone fits directly into the shoulder socket and provides a greater range of angulation, allowing the dog to stretch its front legs out when leaping forwards or running. The front of the shoulder joint in most healthy breeds is in vertical alignment with the dogs' forepaws. Numerous muscles connect the shoulder blades to the forelegs, the spine, the exterior ribcage and the neck.
When the dog's shoulder joints and surrounding muscles are functioning normally, it moves with ease. As a dog increases speed, its gait changes from a trot to a run and its forelegs extend to their full range, and as a result, the dog will lower its head to just above back level and extend it slightly. This allows increased shoulder angulation. If the dog is not accustomed to quick running bursts, it may suffer muscle strain that results in shoulder pain.
Injury to the shoulder joint will cause limping that may appear as though the injury is lower on the foreleg. The dog may put slight pressure or no pressure at all on the paw. Stand in front of your dog and view its entire body, noting whether its shoulders are even. In addition, gently run your hands over the shoulder to check for swelling or an external injury.
If you witnessed the cause of the injury, you're a step ahead. However, most of the time, the dog owner doesn't realise anything is wrong until the dog begins to limp. Think back to the most recent activities. If your dog jumped even a short distance or ran quickly, it could be suffering from a stress injury to the muscles and tendons or to the shoulder joint itself. If the pain is severe, your veterinarian will want to know what activity occurred prior to the injury.
Your veterinarian may take X-rays to determine the extent of the injury. In a number of dogs, Osteochondrosis (OCD), a condition in which the cartilage of the shoulder develops incorrectly, mimics injury to the shoulder joint, and relatively small jumps result in pain and swelling. Shoulder injuries are more common in larger dogs.
Most shoulder injuries that involve muscle stress or small tears resolve themselves within a week or two without treatment, but a veterinarian should examine any dog who is in severe or even mild pain that lasts longer than 2 weeks.