Pain, stiffness or weakness in the dog's hind legs are the most common symptoms of hip dysplasia, according to WebMD. However, mild cases may not affect the dog in daily life but still be apparent on X-rays or other diagnostic tests.
Hip dysplasia is a common genetic disease, although it can also be caused by diet, as described by VCA Animal Hospitals. The hip joint is where the femur connects with the pelvis. In dogs with hip dysplasia, the head of the femur does not form properly, so it does not fit into the socket correctly. This leads to other complications, such as degenerative joint disease or osteoarthritis. In dogs with mild hip dysplasia, these changes may not be noticeable until late in life, but in severe cases, even young puppies show signs of pain.
Some signs of hip dysplasia may be subtle, according to PetMD. Early in the disease, the most notable symptoms may be loose joints during physical exams. As the disease progresses, painful symptoms, such as stiffness and an altered gait, may become evident after exercise. The dog may be more reluctant to climb stairs or perform other activities that require the joints to extend. Some dogs may stand with their hind legs very close together, and there may be a noticeable loss of muscle in the hind limbs.