Osteoporosis (Atrophy)
Osteosis
- Also called Aseptic necrosis or Ischaemic necrosis
- Degeneration and necrosis of osseous tissue
- Due to bone marrow pressure and ischaemia resulting from
- Fractures
- Excessive heat e.g. horn disbudding
- Neoplasia (osteosarcoma and lymphosarcoma)
- Grossly:
- Necrotic bone difficult to recognise
- Sometimes, periosteum becomes dry, dull and detaches easily
- On longitudinal section
- Yellow-white necrotic bone
- Scattered cancellous and endosteal bone
- Histologically:
- Empty lacunae or contain dead osteocytes
- Matrix remains mineralised
- Necrotic bone is slowly resorbed, sequstered or covered by new woven bone
- Persists
- May not be detected radiographically
- Associated with Calve-Legg Perthe's disease
Bone cysts
- May be seen radiographically
- Must be distinguished from neoplasia
- Expansile lytic masses
- Do not appear aggressive
- Subchondral cysts
- Common in horses and pigs
- Usually manifestations of osteochondrosis and DJD
- Simple cysts
- May contain clear colourless fluid, or serosanguinous
- Wall of dense fibrous tissue, woven or lamellar bone
- Aneurysmal bone cysts
- Expansie lesions
- Arise from disturbance of vascular tissue of bone marrow
- Grossly:
- Appear as blood filled sponge
- Spaces separated by fibrous trabeculae
- Histologically:
- Proliferation of undifferentiated mesenchymal cell with multinucleated osteoclast-like cells
- Haemorrhage and haemosiderosis
- Radiography is essential to help differentiate with cavity of a neoplasm
Calcium hydroxylapatite deposition disease
- Gt Dane puppies with paraplegia
- Calcium phosphate depositon has been reported in multiple diarthrodial joints of the axial and appendicular skeleton
- More about Calcium hydroxylapatite deposition disease
Physeal dysplasia with slipped capital femoral epiphysis
- Slipped capital femoral epiphysis seen in dogs, foals and calves
- Associated with severe trauma
- Pigs – manifestation of osteochondrosis with only minimal trauma required
- Most common type of physeal fracture in small animals and the proximal femur is the most common site
- In horses, physeal dysplasia is synonymus with physitis
- More about Physeal dysplasia