Examination of Musculo-Skeletal System:

It comprises of following special examinations:

Analysis of Gait and Conformation:

• Inspection of gait of animals is necessary to localize the site of lameness.
• Changes in gait and conformation relating to nervous system are discussed under disease of nervous system.
• Computer-assisted analysis of gait (kinematics) and hoof loading (via force plates) are commonly used in equine practice.

Close physical examination:

• Close detailed physical examination of the affected area is necessary to localize lesion.
• Passive movements of limbs are carried out to identify fracture, dislocation and pain on movement.
• Muscles can be palpated for evidence of enlargement, pain or atrophy.

Radiography:

• It is an extremely useful diagnostic method for disease of bones and joints, swelling of soft tissues of limbs which cannot be easily detected in physical examination.
• Detailed radiographic information about the joint capsule, joint cavity, or articular cartilage can be obtained using negative (air), positive, or double-contrast arthrography

Ultrasonography:

• Use of ultrasonographic machines with a 5.0- or 7.5-MHz linear transducer provides a rapid on-farm method for evaluating musculoskeletal, tendon, and joint diseases.
• USG is cheaper method and provides different information than that provided by radiography
• The main indication for ultrasonography of the bovine stifle is evaluation of acute septic and traumatic disorders of the region, when specific radiographic signs are often nonspecific or absent.
• Ultrasonographic imaging can be used to differentiate the pathologic changes in the soft tissue structures of digital flexor tendon sheaths of cattle.
• Ultrasonography is a valuable diagnostic aid for septic arthritis.

Arthrocentesis and synovial fluid interpretation:

• Joint fluid is collected by needle puncture of the joint cavity (arthrocentesis) and examined for the presence of cells, biochemical changes in the joint fluid, and the presence of infectious agents.
• Analysis of synovial fluid is a fundamental requirement for differentiating septic arthritis from degenerative arthritis
• Leukocyte count and differential, erythrocyte count, total protein concentration, and an index of viscosity usually provide sufficient information for clinical use.
• Angled needle insertion reduces joint contamination relative to perpendicular insertion.
• Insertion of a spinal needle with the stylet in place also reduces joint contamination with hair, relative to insertion without the stylet.

Arthroscopy:

• Special endoscopes are available for inspection of the joint cavity and articular surfaces (arthroscopy).
• Diagnostic and surgical arthroscopy are now common place in specialized equine practice.
• Surgical arthroscopy is rapidly replacing conventional arthrotomy for the correction of several common surgical conditions of the musculoskeletal system of the horse.

Serum Biochemistry and Enzymology:

• When disease of bone or muscle is suspected, the serum concentration of calcium and phosphorus, the serum alkaline phosphatase activity, and the serum activity of two muscle-derived enzymes, creatinine kinase (CK) and aspartate aminotransferase (AST), also known as serum glutamic oxaloacetic transaminase (SGOT), may be useful.
• CK and AST are sensitive indicators of muscle cell damage, with CK also being specific.
• Other serum biochemical indicators of muscle damage that have been used in experimental studies include myoglobin, a low molecular-weight protein that is an early marker of muscle damage, and two indices of muscle damage: myosin, a high-molecular weight protein, and 3-methylhistidine, a post translationally modified amino acid released after myosin or actin degradation.

Muscle biopsy:

• It may be useful for microscopic and histochemical evaluation.

Infrared thermography:

• Infrared thermography has been increasingly applied to the diagnosis of inflammatory conditions of muscles and tendons, in that acute inflammation is associated with localized heat that can be detected by using a camera capable of imaging the infrared spectrum.

Nuclear scintigraphy:

• Scintigraphy is a technique in which radioisotope attached to drugs are travelled to specific organ or tissues to obtain image or record of its functioning.
• Use of nuclear scintigraphy has declined with the increased availability and resolution of ultrasonographic and magnetic resonance imaging (MRI) units.
• Scintigraphy is still a valuable diagnostic method for bone diseases such as osteomyelitis of the vertebral column in adult horses and cattle when the lesion is surrounded by a large mass of superimposing muscle

Magnetic Resonance Imaging (MRI):

• MRI is a cross-sectional imaging modality that provides outstanding tissue contrast and multiple views of the region of interest.
• It is being increasingly used for diagnosis of musculoskeletal disease and related research studies.
• Availability is only limited to referral centre due to high cost of equipment and specially structured tables have to be made.
• It is anticipated that rapid advances will be made in the clinical application of MRI to the diagnosis of specific musculoskeletal injuries, such as evaluating cartilage damage and navicular disease in horses.

Computed Tomography:

• CT scan images can be used to see the position, size and shape of muscles, bones and organs.
• CT scan shows muscle damage and bone abnormalities.
• It has not been used much in clinical analysis of musculoskeletal tissue due to rapid advancement in MRI imaging technique.

Nutritional History:

• Because most important osteodystrophies and myopathies are nutritional in origin, complete nutritional history must be obtained.
• It includes analysis of feed and determination of total amount of intake of each nutrient, including ratio of one nutrient to another in diet.

Environment and Housing:

• When outbreaks of lameness occur in housed cattle, sheep, goats, and pigs, the quality of the floor must be examined to evaluate the possibility of floor-related injuries.