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Diagnostic Approach to Musculo-Skeletal System:

Recumbent animals with musculoskeletal conditions can present diagnostic challenge to veterinarians. A multitude of metabolic, infectious, toxic, degenerative and traumatic disorder can result in recumbency.

Locomotor system is very much important in maintaining posture and gait of animals. Deformities of this system may be primarily due to involvement of locomotor organs or as a result of generalized deficiency or metabolic derangements.

Examination of musculoskeletal organs is considered as orthopedic examination. For this examination, adequate knowledge of structure and function of locomotor organs is required. following processes may be employed in locating disease:

 

Signalment and History:

  • Examination should begin with determination of affected animal’s signalment, i.e. age, breed, gender, weight, production status and intended use.
  • Age, gender and production status should be carefully considered when developing differential diagnosis.
  • Animal’s age and size often influence the prognosis of disease associated with musculoskeletal system.
  • Description of nature of parturition and size of calf should be obtained for recumbent post-parturient heifers. Dystocia or fetopelvic disproportion can traumatize the lumbar root of the sciatic and obturator nerves, resulting in calving paralysis
  • Pathologic fractures of the pelvis or vertebral column may result from primary or secondary dietary deficiencies of calcium, phosphorus, vitamin D, or copper.
  • Sudden increases in activity, such as turnout of animals onto pasture after a period of confinement, may precipitate clinical signs of myodegeneration caused by vitamin E and/or selenium deficiency.
  • Injuries related to fighting or mounting behavior may be seen when recent social interactions have occurred within the herd (e.g., mixing of groups of animals, introduction of new animals).
  • Assessment of the treatment history and a complete physical examination are necessary to determine whether recumbency likely reflects inadequate treatment, misdiagnosis, relapse, or concurrent disease or injury. For example, inability to stand after treatment with calcium salts is a common complication of refractory periparturient hypocalcemia in dairy cows.
  • Administration of isoflupredone acetate to treat ketosis in dairy cattle has been associated with flaccid muscular weakness and recumbency caused by severe hypokalemia.
  • Cows and heifers in estrus, with cystic ovarian disease, or that have recently been given prostaglandin F2α or hormones for superovulation may be injured when mounted.
  • The location and technique used to administer any recent injections should be determined. The sciatic nerve may be damaged if irritating drugs are deposited between the greater trochanter and the tuber ischiadicum.
  • Cattle that are recumbent for longer periods, particularly if they are on a hard surface and unable to change position, are prone to develop pressure damage on the down-side hindlimb muscles and nerves.
  • Cattle with a history of falling into or being found in sternal recumbency with both hindlimbs in abduction should be carefully evaluated for pelvic fracture, coxofemoral luxation, fracture of the greater trochanter of the femur, and pressure myopathy or rupture of the adductor muscles of the medial thigh.
  • Ice, mud, smooth or wet concrete, and slopes that are steep or have loose soil may cause healthy cattle to slip and fall; ill or debilitated cattle that become recumbent on these surfaces are prone to injuries during attempts to rise. So the site of recumbent animals and nature of surface on which it lies should also be considered.

 

Physical Examination:

  • It is important for veterinarians to consider the possibility of the paralytic form of rabies as a cause of recumbency and to take appropriate caution during handling.
  • Animals should be examined from distance at first. Resting respiratory rate should be recorded.
  • Animals and its visual surroundings should be visually inspected.
  • Animals injured while being mounted frequently have roughened, broken hairs over the rump and tail head.
  • Cattle that are recumbent because of primary musculoskeletal injuries are typically bright and alert. Profound depression in a recumbent animal is often indicative of severe systemic diseases of infectious, toxic, or metabolic origin; a thorough evaluation of the neurologic system is indicated in such cases.
  • an animal’s mental status, ability to eat and drink, and willingness to attempt to rise have significant influence on the outcome and are worthy of consideration when making a prognosis

 

Hindlimb and Pelvis Examination:

  • Animals that are recumbent due to musculoskeletal disease should be examined first from distal aspect of both hindlimb with assessment of digits.
  • Severe, acute laminitis occasionally makes an affected animal unable or unwillingness to rise.
  • Because of a lack of thick overlying muscle, the bones distal to the stifle and proximal to the coronet can be readily assessed by inspection and palpation
  • Manipulation of the stifle, hock, fetlock, and digital joints into full flexion and extension should be performed. During manipulation, examiners should feel for crepitus in each joint and observe the animal’s response to manipulation.
  • The integrity of collateral ligamentous support can be assessed by palpating the medial and lateral aspects of these joints during abduction and adduction, respectively. Each joint should be palpated for effusion and heat.
  • Rupture of the gastrocnemius muscle or tendon may occur when recumbent cattle struggle to rise. Rupture most commonly occurs at the junction of the muscle and tendon, approximately 8 to 12 cm proximal to the hock. Hematoma formation around the muscle tear results in a warm, nonpainful swelling surrounding the gastrocnemius at the caudal aspect of the crus. The tendon of the gastrocnemius remains relaxed during hock flexion. If an animal attempts to bear weight on the affected limb, the hock remains flexed, the point of the hock drops, and the plantar aspect of the metatarsus may contact the ground.
  • Rupture of the cranial cruciate ligament results in marked effusion of the femoropatellar joint. Increased craniocaudally movement of the tibia relative to the femur (a positive drawer sign) may be evident with cranial cruciate ligament injury.
  • Examiners can test the integrity of the cranial cruciate ligament by placing one hand on the tuber calcanei and the other on the tibial crest and rotating the tibia internally. If the cranial cruciate ligament is ruptured, increased laxity and crepitus may be evident when the tibia is rotated internally.
  • Collateral ligament rupture of the stifle also results in significant effusion in the femoropatellar joint. In animals with medial collateral ligament rupture, increased medial laxity of the stifle (manifested as widening of the femorotibial joint) can be induced with the limb placed in abduction.
  • Increased lateral laxity of the stifle during adduction of the limb is expected with rupture of the lateral collateral ligament.
  • The hindlimb muscles should be palpated for swelling and pain. Firm swelling and pain in multiple muscle groups may be evident in recumbent animals affected with acute nutritional myodegeneration (white muscle disease)
  • Subcutaneous emphysema, which may accompany certain types of bacterial myositis, may produce crepitus during muscle palpation.
  • To evaluate muscle tone, the limb musculature should be palpated and the hindlimb’s resistance to flexion and extension assessed.
  • The muscles of the crus and caudal thigh are susceptible to pressure myopathy, which results from prolonged sternal recumbency with a hindlimb maintained beneath the animal.
  • The sciatic nerve may be damaged at the caudal aspect of the femoral neck by pressure to the down-side hindlimb. Palpation and inspection of the cranial tibial, peroneus tertius, biceps femoris, semitendinosus, and semimembranosus muscles of the up-side hindlimb can give an examiner a basis of comparison for subsequent examination of these muscles in the down-side hindlimb.
  • Muscles damaged by pressure may be visibly and/or palpably swollen, although the absence of swelling does not rule out pressure damage.
  • The quadriceps muscle group may be torn or ruptured in cattle that fall with the hindlimbs abducted or if the hindlimbs are forcefully extended.1 Measurement of serum creatine phosphokinase and aspartate aminotransferase activity may aid in determining the severity of recent or ongoing muscle damage.
  • Recumbent cattle should be carefully evaluated for coxofemoral luxation and fractures of the pelvis and femur. Spatial relationship of tuber coxae, tuber ischiadicum and greater trochanter of femur is evaluated. In normal animals, they form triangle. This triangular spatial relationship may be disrupted in animals with fractures of the proximal femur or pelvis or coxofemoral luxation.
  • Placing one hand on the greater trochanter, examiners should manipulate the hindlimb into full abduction and adduction and move the coxofemoral joint through its full range of flexion and extension. While moving the hindlimb, examiners may feel or hear coarse crepitus in animals with femoral or pelvic fractures or ligamentous stifle injury.
  • Excessive mobility of the greater trochanter during movement of the coxofemoral joint may be present in animals with coxofemoral luxation, which is difficult to distinguish from a fracture of the proximal femur during physical examination. Radiographs are often necessary to distinguish between these conditions, particularly if surgical repair is being considered.
  • The greater trochanter is displaced dorsally from its normal position in animals with craniodorsal or caudodorsal luxation of the coxofemoral joint resulting in disruption of the normal triangular relationship between the tuber coxae, tuber ischiadicum, and greater trochanter on the affected side. If such an animal is placed in lateral recumbency, the hindlimbs can be extended and their lengths compared; the affected limb may appear to be shorter than the normal side.
  • Rectal examination should be performed after external examination of the hindlimbs is completed.
  • The symmetry of the internal surfaces of the pubis, ilium, sacrum, and ischium should be evaluated on each side. An assistant may perform hindlimb manipulation or may rock the animal’s pelvis back and forth as the examiner feels for crepitus suggestive of pelvic fractures.
  • A hematoma may be palpable in the soft tissue surrounding fractures of the sacrum, iliac shaft, or pubis.
  • The femoral head may be palpable within the obturator foramen in animals with caudoventral luxation of the coxofemoral joint.

 

Forelimb Examination:

  • Examination of the forelimbs may reveal significant injuries that occurred because of recumbency.
  • Cattle that remain in lateral recumbency for long periods may develop secondary compression damage to the brachial plexus and/or radial nerve of the down-side forelimb, particularly if the limb is trapped beneath an animal’s thorax.
  • Abrasions or lacerations on the dorsum of the carpi are a common complication in cattle that struggle to rise on rough cement, and these injuries occasionally result in open wounds of the carpal joints.

 

Vertebral Column Examination:

  • Palpation of the vertebral column can be difficult in well-muscled or overconditioned cattle.
  • Beginning at the tailhead, examiners should palpate the spinous processes of the thoracolumbar vertebral column. Focal depression, elevation, or lateral deviation of the spinous processes may indicate fracture or subluxation.
  • Displaced fractures of the vertebral column located between the second thoracic and sacral vertebrae may result in hindlimb paresis or paralysis; affected cattle may acquire dog-sitting posture when attempting to rise
  • Displaced fractures in the cervical spine usually result in tetraparesis and/or tetraplegia; affected animals typically lie in lateral recumbency and are unable to right themselves into sternal recumbency.
  • As vertebral injuries result in nerve damage, spinal cord damage, examination of spinal reflexes is necessary for complete physical examination of vertebral column.
  • The hindlimb withdrawal (flexor) response should be evaluated by pinching the skin over the coronet with forceps, pliers, or hoof testers. The withdrawal response tests the integrity of the sensory and motor components of the sciatic nerve and the sixth lumbar and first and second sacral segments of the spinal cord.
  • The patellar response tests the integrity of the femoral nerve, the response arc involving the fourth and fifth lumbar spinal cord segments, and the quadriceps muscle group.
  • Exaggerated patellar response may be present in cattle with diffuse disease of spinal cord white matter or with focal cord lesion cranial to mid-lumbar region.
  • In the perineal response, pinching of the perianal skin normally results in closure of the anus and flexion of the tail, which requires intact function of both the sacral and caudal components of the spinal cord.
  • Skin sensation over the rump, lumbar region, and thorax can be tested by pinching the skin with forceps or poking the skin with the tip of a needle and observing for a behavioral response indicative of perception of the stimulus.
  • Stimulation of the skin over the thorax and cranial lumbar region elicits contraction of the cutaneous trunci muscle, which results in twitching of the skin of the trunk. It is important to note that the cutaneous trunci response may not be triggered in normal animals when the noxious skin stimulus is applied caudal to the midlumbar region
  • Flexion of the fetlock, carpus, elbow, and shoulder normally occurs when the skin is pinched near the coronet. This response arc tests the integrity of sensory fibers in the radial, median, and ulnar nerves; motor fibers in the axillary, musculocutaneous, median, and ulnar nerves; and the neuromuscular junctions and muscles of the forelimb.
  • To test the triceps response, examiners should strike the triceps tendon with a heavy plexor and observe for elbow extension. It may be difficult to demonstrate in heavy cattle.

 

Inspection of animal

  • Animals are observed for their gait and posture in this examination.
  • Posture of animals should be noted in recumbent and standing position.
  • Gait of animals is observed during walking. Animals are made to walk in various directions and walking animals should be observed from both front and rear view to recognize the activity of all locomotion.
  • Lameness may be graded as follows:
    • Grade- I Mild
    • Grade-II Moderate
    • Grade-III Pronounced
    • Grade- IV Severe
    • Grade- V Highly Severe

 

Clinical Pathology:

  • Blood count and urine analysis should be performed.
  • Synovial fluid examination is carried out.
  • Cytologic examination of impression smears or needle aspirate
  • Culture and in-vitro sensitivity of joint fluids to initiate antibacterial therapy

Normal synovial fluid:

  • Small in amount, clear, doesnot coagulate, protein content <2g/100 ml, cells are upto 300 per mm3 with few or no RBC and neutrophils.

 

Radiography:

  • Radiography of bones and joints is valuable diagnostic tools to evaluate conditions of bone and joints.
  • USG is done to know the condition of soft tissues
  • Other procedure involved in diagnosis are arthroscopy, bone scintigraphy, electromyography, thermography and muscle biopsy.
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