What Are Some Diseases of the Skeleton?Congenital diseases.
Certain congenital and developmental bone diseases occur in the dog. Examples include the following: Panosteitis is an inflammation in the marrow cavity of the long bones. It affects primarily young, large- or giant breed dogs. Affected animals show signs of pain in the bone, lameness, fever and lethargy.
Hip dysplasia is abnormal development of the hip joint that causes the ball and socket of the joint to be looser than normal. Hip dysplasia occurs primarily in large breed dogs. Clinical signs may occur in young dogs or arise later in life as degenerative arthritis develops. Affected dogs may develop lameness, a bunny-hopping gait in their rear legs, a reluctance to walk, and stiffness in the rear legs.
Osteochondrosis dissecans (OCD) is a defect in the smooth cartilage surface within one or more joints, especially in the shoulder, elbow, hock and knee (stifle). It occurs primarily in young, growing, large breed dogs.
Hypertrophic osteodystrophy (HOD) is an inflammation in the growth plates of the long bones. It usually causes swelling and pain of the bone just above the joints, and primarily affects young, growing, large- and giant breeds of dogs.
Multiple cartilaginous exostoses are abnormal proliferations of bone in certain areas, such as the long bones, ribs, and vertebrae. They occur in young dogs and may cause lameness and discomfort.
Numerous other developmental abnormalities of joints may affect young dogs, such as aseptic necrosis of the head of the femur, dislocation of the knee cap (patella), and elbow dysplasia.
Osteomyelitis. Osteomyelitis is an inflammation of bone that is usually caused by a bacterial infection. Infections of the bone may also arise with certain fungal infections and in the presence of bone implants, such as bone plates and pins.
Nutritional disorders. Some disorders that cause abnormalities in the circulating levels of calcium, phosphorous and certain vitamins can adversely affect bones. Examples include:
Rickets is severe weakening of the bone due to calcium deficiency or imbalances in the diet. It arises most often in young dogs fed an all meat diet. In puppies it causes lameness, deformities and fractures of the bone.
Chronic kidney failure affects bone by altering the amount of phosphorus and vitamin D in the body. The bones become soft, thin, and weak.
A deficiency in vitamin D in the diet, or low conversion of vitamin D in the body from a lack of exposure to sunlight, can affect the development of bone. Lameness, bony deformities and fractures may occur.
Trauma. Trauma to bones is perhaps the most common skeletal disorder encountered in the dogs, especially dogs allowed to roam free. Dogs that are injured through falls, automobile accidents or fights can experience a variety of bony fractures and dislocations.
Cancer. Neoplasia or cancer of bone occurs in the dog. Tumors may arise within the tissues of the bone or may invade bones from the surrounding soft tissues. Large breed dogs develop more bone cancer than do small breed dogs. Dogs may also develop cancers of the bone marrow, such as lymphosarcoma.
What Types of Diagnostic Tests Are Used to Evaluate the Skeleton?
Physical examination and palpation of bones. The initial evaluation of the skeleton involves a thorough examination, with palpation of the bones and joints. The animal may be observed in the examination room for signs of lameness and abnormalities in gait.
Radiography. Cortical and cancellous bone and some forms of cartilage show up very well on plain x-rays. For this reason, plain x-rays are an important tool in evaluating the skeleton. Some x-rays may be taken with the animal awake and sedated, while other x-rays may require that the animal be completely anesthetized.
Routine laboratory tests. A complete blood count and biochemistry profile may be taken to look for signs of infection and abnormalities in circulating levels of calcium and phosphorus. These tests are also helpful to detect other disorders that may affect the bones, such as kidney disease, anemia and leukemia.
Special laboratory tests. If an infection of bone is suspected, then samples may be collected for bacterial and fungal cultures. Serologic tests for fungal diseases may also be submitted. Occasionally the levels of vitamin D and parathyroid hormones are measured in the blood.
Bone biopsy. Identification of the type of bone disease present may require a bone biopsy. This is especially true in cases of congenital and developmental bone diseases, osteomyelitis and tumors of bone.
Bone marrow biopsy. Biopsy of the bone marrow cavity is done via passage of a needle into the red bone marrow of one or more bones and aspiration of a sample of the bone marrow. The bone marrow sample is then sent to a veterinary pathologist for microscopic examination.
Advanced imaging techniques. CT and MRI are very useful in examining bones and their adjacent soft tissues, such as cartilage, ligaments, and tendons. Radioisotope bone scans are also helpful in some cases. To arrange these tests often requires that your dog be referred to a veterinary orthopedic specialist or a veterinary radiologist.
Chest x-rays. Chest x-rays may be taken to look for evidence of infection or tumors that have spread to the lungs, and to identify abnormalities in the ribs or vertebrae of the chest.