Bones 7

• For wobbles syndrome in horses where does the defect in articular facets occur 


  Horse - C3-C5
• For wobbler syndrome in dogs where does the defect in the articular facet occur 


  Dog - C6 to C7
• Describe the 3 types of bone fractures

  1.impacted -one segment of bone is driven into another

  2.green stick -periosteum of bone is still intact

  3.avulsion- bone fragment torn away with ligament or tendon
• Explain the process of fracture repair 


  1.henatoma forms at the site of the fracture

  2.ischemic necrosis of the adjacent bone occurs

  3.primitive mesenchymal cells proliferate to form a layer of periosteum

  4. external and internal Callus formation occurs

  5. Callus matures

  6. Callus modeling occurs to restore the original shape and strength
• What causes osteochondrosis 


  Damage to articular epiphyseal complex cartilage blood supply during early growth is the first step
• Second step in osteochondrosis 


  Necrosis occurs because of lack of nutrients to the area

  Then as it continues to bear weight on the necrotic cartilage it eventually forms a cleft
• Third step in osteochondrosis 


  Clefts may join with articular surface to form a flap or may separate entirely from loose bodies this is called osteochondritis dissecans
• What is common cause for osteochondrosis in young animals 


  Ischaemic damage to growing cartilage
• Aeitology of hip dysplasia 


  Genetic component -heritibility varies frin 0.2 to 0.6

  Environmental effects-overfeeding

  Indiscriminate Breeding-small country limited gene pool

  Lesions in puppies are most sever because of fast growth in first few weeks of life
• What is hip dysplasia characterized by 


  Subluxation of hip joint due to lack of conformity between acetabulum and femoral head
• Predisposing factors of hip dysplasia 


  • Low pelvic muscle mass eg German Shepherd
  • Hypotrophy of pectineus muscle shortened muscle upward force of femoral head on dorsal rim of acetabulum