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[[Image:Hypertrophic osteodystrophy.jpg|right|thumb|100px|<small><center>Hypertrophic osteodystrophy (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
[[Image:Hypertrophic osteodystrophy.jpg|right|thumb|100px|<small><center>Hypertrophic osteodystrophy (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
*Also called - '''metaphyseal osteopathy'''
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Also known as: '''''Metaphyseal Osteopathy — HOD'''''
*Young (usually 3-6 months old), fast growing '''dogs''' of large or giant breeds
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*'''Distal radius and ulna''' most severely affected
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==Introduction==
*Clinical signs:
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This is a '''developmental disease''' of '''young, large, rapidly-growing large and giant breeds''' such as the Great Dane, St Bernard, Irish Setter, Labrador, German Shepherd, Doberman and Weimaraner.
**Fever
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**Anorexia
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It most frequently presents at the age of '''3-4 months''' (range 2-8) and '''males''' are affected more commonly than females.
**Severe lameness
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**Swelling in '''metaphyses''' of long bones corresponding with neutrophilic infiltrate
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The disease occurs at the metaphysis of long bones, especially the '''distal ulna and radius'''.
*Radiologically:
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**Increased lucency and increased density areas in metaphyses
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The aetiology of the condition is '''unknown''', but theories include: an excessive plane of nutrition, calcium/phosphate imbalance, vitamin C deficiency or an '''infectious agent'''.
**Enlarged metaphyses
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*Usually bilaterally symmetrical
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==Clinical Signs==
*Histologically:
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Respiratory or gastrointestinal illness may precede the onset of skeletal disease.
**Haemorrhage and necrosis of [[Bones - Anatomy & Physiology|osteoblasts]] in the growth plates and primary spongiosa
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**Intense infiltration by [[Neutrophils|neutrophils]]
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Clinical signs vary from '''mild lameness to severe systemic illness''', pyrexia, depression, inappetance, weight loss and inability to stand.
**Periosteal reaction + formation of new bone on external surface above the lesion
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*Many resolve spontaneously with complete remodelling and healing of the bone
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'''Pain''' can be elicited by digital pressure on the metaphysis.
*Can progress to '''periosteal bone proliferation'''
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*Cause is unknown
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The condition is usually '''bilaterally symmetrical''' and may affect all four limbs.
**Unlikely to be dietary deficiency
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**Likely to be infectious cause
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In severe cases, the long bone metaphyses are visibly '''swollen, hot and painful on palpation'''.
*Contrast with [[Panosteitis|'''canine panosteitis''']]
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Active periods of disease may last for several days and '''relapses''' may occur at intervals of 1-6 weeks.
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Some severely suffering dogs may '''die''' or may be euthanised on owner's request.
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==Diagnosis==
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The clinical signs and presentation are suggestive.
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'''Radiography''' can confirm the diagnosis. Findings include:
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:irregular radiolucent line (double physeal line) in the metaphysis, parallel to the normal radiolucent physeal line
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:the physis may appear widened
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:subperiosteal new bone formation at the metaphysis forming a collar of bone, also known as bone cuffing
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:evidence of growth deformities
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Bone '''scintigraphy''' may reveal increased uptake of agent at the metaphysis.
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Haematology and biochemistry are usually unremarkable.
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'''Histology''' of the area would reveal: haemorrhage and necrosis of [[Bones - Anatomy & Physiology|osteoblasts]] in the growth plates and primary spongiosa, intense infiltration by [[Neutrophils|neutrophils]], periosteal reaction and formation of new bone on external surface above the lesion.
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==Treatment==
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HOD is usually '''self-limiting''' and mildly affected dogs '''recover within a few weeks'''.
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Treatment involves '''supportive care with proper nutrition, fluids and analgesia'''.
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Buffered aspirin is the preferred analgesic.
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In severe cases, '''corticosteroids and antibiotics''' may be indicated, depending on blood culture results. Recumbent puppies should be turned every 4 hours and placed in a well-padded cage.
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Correction of '''angular limb deformities''' may be necessary.
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==Prognosis==
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This is related to disease severity.
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'''Mildly affected dogs''' have a '''good prognosis''' and many recover spontaneously. Diaphyseal deformities can be severe but are usually not debilitating.
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'''Severely affected dogs''' have a '''poor prognosis''' and some dogs can succomb to '''hyperthermia or acidosis'''. Euthanasia may also be performed on the worst cases.
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{{Learning
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|flashcards = [[Small Animal Orthopaedics Q&A 04]]
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}}
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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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Dunn, J. (1999) '''Textbook of small animal medicine''' ''Elsevier Health Sciences''
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Hosgood, G. (1998) '''Small animal paediatric medicine and surgery''' ''Elsevier Health Sciences''
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[[Category:To Do - Helen]]
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[[Category:To Do - Review]]
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[[Category:Bones - Hyperplastic Pathology]]
 
[[Category:Bones - Hyperplastic Pathology]]
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