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| + | *Almost exlusively in small dogs, particularly terriers and poodles |
| − | Also known as: '''''Avascular Necrosis of the Femoral Head — Femoral Head Necrosis — Legg Perthes disease — Osteochondritis juvenilis — Coxa plana'''''
| + | *Clinical signs appear at age of 4-11 months |
| − | | + | *Grossly: |
| − | ==Introduction==
| + | **[[Osteosis|Aseptic ischaemic necrosis]] in central parts of femoral head |
| − | This condition describes the '''avascular aseptic necrosis of the femoral head and neck in dogs''', which leads to collapse of the coxofemoral joint and [[osteoarthritis]].
| + | ***Possibly due to occlusion of blood vessels |
| − | | + | **Fragmentation of [[Bones - Anatomy & Physiology|trabecular bone]] |
| − | The precise cause is unknown and a specific vascular lesion has not been identified.
| + | **Collapse of femoral head |
| − | | + | **Revascularisation of femoral head |
| − | '''Pathophysiology''' of the disease, is that interruption of the blood to the femoral head leads to death of osteocytes and collapse and deformation of the femoral head during normal loading. The articular cartilage becomes thickened, clefts develop and there is fraying of the superficial layers.
| + | **Formation of new bone and [[Musculoskeletal Terminology - Pathology|osteophyte]] formation around femoral head and acetabular rim prior to old bone reabsorption |
| − | | + | **-> severe degenerative arthropathy |
| − | It occurs most commonly in '''small and miniature breeds of dogs''' such as the Yorkshire Terrier, Chihuahua and miniature Poodle, between '''4 and 11 months of age'''.
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| − | The condition is '''usually unilateral''' but can be bilateral.
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| − | ==Clinical Signs==
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| − | There is usually a '''gradual-onset pelvic limb lameness''' which is usually weight-bearing.
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| − | There may be '''muscle atrophy''' in the affected limb.
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| − | '''Pain on palpation''' and manipulation of the hip joint is severe and '''crepitation''' may be noted.
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| − | The animal is usually otherwise normal.
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| − | ==Diagnosis==
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| − | History and clinical signs are suggestive.
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| − | '''Radiography''' allows a definitive diagnosis to be made, and findings include:
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| − | :Irregular areas of lysis at the femoral head and neck
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| − | :Irregular density of the head and neck
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| − | :Widening of the articular space
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| − | :Flattening and collapse of the subchondral bone of the head
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| − | :Evidence of degenerative joint disease around the femoral head and acetabular rim such as osteophytes | |
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| − | '''Histological findings''' include: [[Osteosis|Aseptic ischaemic necrosis]] in central parts of femoral head, fragmentation of [[Bones - Anatomy & Physiology|trabecular bone]].
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| − | ==Treatment==
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| − | '''Conservative treatment''' involving cage confinement and analgesia may be successful in a minority of patients.
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| − | '''Femoral head and neck excision''' is the treatment of choice and is tolerated very well by small dogs. '''Passive physiotherapy''' should be started 3 days after surgery, and '''swimming''' can be helpful once the sutures have been removed. Analgesic and anti-inflammatories can help in the post-operative period.
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| − | If the disease occurs in a large dog, '''total hip replacement''' can be considered.
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| − | ==Prognosis==
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| − | Prognosis is '''good to excellent for full recovery''' in small dog breeds as they respond well to surgery.
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| − | Affected animals should not be used for breeding as a heritable component is suspected.
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| − | {{Learning
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| − | |flashcards = [[Small Animal Orthopaedics Q&A 13]]
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| − | ==References==
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| − | Pasquini, C. (1999) '''Tschauner's Guide to Small Animal Clinics''' ''Sudz Publishing''
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| − | Shires, P. (2005) '''The 5-minute veterinary consult: muscoloskeletal disorders''' ''Wiley-Blackwell''
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| − | {{review}}
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| − | {{OpenPages}}
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| − | [[Category:Musculoskeletal Diseases - Dog]] | |
| − | [[Category:Expert Review - Small Animal]]
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| | [[Category:Joints - Degenerative Pathology]] | | [[Category:Joints - Degenerative Pathology]] |