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| − | {{toplink
| + | #REDIRECT[[:Category:Bones - Degenerative Pathology]] |
| − | |backcolour =CDE472
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| − | |linkpage =Musculoskeletal System - Pathology
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| − | |linktext =Musculoskeletal System
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| − | |maplink = Musculoskeletal System (Content Map) - Pathology
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| − | |pagetype =Pathology
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| − | |sublink1=Bones - Pathology
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| − | |subtext1=BONES
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| − | }}
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| − | <br>
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| − | <big>
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| − | [[Bones Metabolic - Pathology|'''Bones and Cartilage - Metabolic diseases''']]
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| − | [[Bones Fractures - Pathology|'''Bones and Cartilage - Fractures''']]
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| − | </big>
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| − | ===Osteoporosis (Atrophy)===
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| − | *Lesion, not a disease
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| − | *Reduction in bone mass due to reduced osteoid (bone atrophy)
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| − | *Bone resorption exceeds formation -> pathological loss of bone
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| − | *Resorbed from:
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| − | **Trabeculae, preserving the weight bearing ones until last
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| − | **Endosteal surface of cortical bone
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| − | **Along vascular channels
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| − | *Longitudinal section
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| − | **Fewer thin trabeculae
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| − | **Enlarged medulla
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| − | **Thin, porous cortex
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| − | *Bone which remains is normally mineralised
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| − | *Can be localised or generalised*Caused by:
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| − | **Starvation - in farm animals due to protein and energy deficiency
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| − | **Nutritional deficiency (calcium) and hypocalcaemia -> bone resorption
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| − | **Senility
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| − | ***Physiological loss of skeletal mass with age
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| − | ***May be excessive in some individuals
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| − | ***Histologically - dead [[Bones - normal#Normal stucture|osteocytes and empty lacunea]]
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| − | **Physical inactivity (disuse) - muscular inactivity and reduced weight bearing, e.g. during limb casting
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| − | **Glucocorticoids
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| − | **[[Intestine - Parasites|Intestinal parasitism]] - in ruminants, malabsorption due to severe infestation
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| − | **[[General Pathology - Congenital and Neonatal Disease#Copper Deficiency|Copper deficiency]] - in lambs, calves, foals, pigs and dogs -> brittle bones
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| − | *May be reversed in young growing animals
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| − | ===Osteosis===
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| − | *Also called '''Aseptic necrosis''' or '''Ischaemic necrosis'''
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| − | *Degeneration and necrosis of osseous tissue
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| − | *Due to bone marrow pressure and ischaemia resulting from
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| − | **[[Bones Fractures - Pathology|Fractures]]
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| − | **Excessive heat e.g. horn disbudding
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| − | **Neoplasia ([[Bones Hyperplastic and Neoplastic - Pathology#Osteosarcoma|osteosarcoma]] and [[Bones Hyperplastic and Neoplastic - Pathology#Lymphosarcoma|lymphosarcoma]])
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| − | *Grossly:
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| − | **Necrotic bone difficult to recognise
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| − | **Sometimes, periosteum becomes dry, dull and detaches easily
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| − | **On longitudinal section
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| − | ***Yellow-white necrotic bone
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| − | ***Scattered cancellous and endosteal bone
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| − | *Histologically:
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| − | **Empty [[Bones - normal#Normal structure|lacunae or contain dead osteocytes]]
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| − | **Matrix remains mineralised
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| − | *Necrotic bone is slowly resorbed, sequstered or covered by new woven bone
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| − | *Persists
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| − | *May not be detected radiographically
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| − | *Associated with [[Joints Degenerative - Pathology#Calve Legg-Perthe's disease|Calve-Legg Perthe's disease]]
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| − | ===Bone cysts===
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| − | [[Image:Bone cysts dog.jpg|right|thumb|100px|<small><center>Bone cysts (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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| − | *May be seen radiographically
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| − | *Must be distinguished from [[Bones Hyperplastic and Neoplastic - Pathology#Neoplastic|neoplasia]]
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| − | *Expansile lytic masses
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| − | *Do not appear aggressive
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| − | *'''Subchondral cysts'''
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| − | **Common in horses and pigs
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| − | **Usually manifestations of [[Joints Developmental - Pathology#Osteochondrosis|osteochondrosis]] and [[Joints Degenerative - Pathology#Degenerative joint disease (DJD)|DJD]]
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| − | *'''Simple cysts'''
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| − | **May contain clear colourless fluid, or serosanguinous
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| − | **Wall of dense fibrous tissue, [[Bones - normal#Bone organisation|woven or lamellar bone]]
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| − | *'''Aneurysmal bone cysts'''
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| − | **Expansie lesions
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| − | **Arise from disturbance of vascular tissue of bone marrow
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| − | **Grossly:
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| − | ***Appear as blood filled sponge
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| − | ***Spaces separated by fibrous trabeculae
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| − | **Histologically:
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| − | ***Proliferation of undifferentiated mesenchymal cell with multinucleated osteoclast-like cells
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| − | ***Haemorrhage and haemosiderosis
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| − | *Radiography is essential to help differentiate with cavity of a neoplasm
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| − | ===Calcium hydroxylapatite deposition disease===
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| − | *Gt Dane puppies with paraplegia
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| − | *Calcium phosphate depositon has been reported in multiple diarthrodial joints of the axial and appendicular skeleton
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| − | *[[More on Calcium hydroxylapatite deposition disease|More about Calcium hydroxylapatite deposition disease]]
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| − | ===Physeal dysplasia with slipped capital femoral epiphysis===
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| − | | |
| − | *Slipped capital femoral epiphysis seen in dogs, foals and calves
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| − | *Associated with severe trauma
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| − | *Pigs – manifestation of [[Joints Developmental - Pathology#Osteochondrosis|osteochondrosis]] with only minimal trauma required
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| − | *Most common type of physeal fracture in small animals and the proximal femur is the most common site
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| − | *In horses, physeal dysplasia is synonymus with [[Bones Developmental - Pathology#Physitis|physitis]]
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| − | *[[More about Physeal dysplasia]]
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