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What is osteochondrosis?
failure of endochondral ossification
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What is OCD?
failure of endochondral ossification with a cartilage flap (portion of bone in joint margin that has a lucency)
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What animals are most likely to get OCD?
rapidly growing large breed dogs (6-9 months old)
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What are predilection sites for OCD in dogs? (4)
- caudal humeral head
- medial humeral condyle
- femoral condyles
- trochlear ridges of the talus
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What are the radiographic signs of OCD? (4)
- flattening, concavity of the bone surface
- apparent joint space widening focally
- cartilage flap- only seen on rads if mineralized, seen on arthrogram or MRI
- degenerative joint disease
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If you diagnose OCD in the limb of a dog, your next step should be...
do rads of the contralateral leg.... it's commonly bilateral!
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What are common sites of OCD in horses? (5)
- medial femoral condyle
- lateral trochlear ridge of femur
- intermediate ridge of the tibia (DIRT)
- lateral trochlear ridge of the talus
- medial malleolus
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What are the major 3 developmental elbow diseases in dogs and what results from them?
- Ununited anconeal process
- Medial humeral osteochondrosis
- Fragmented medial coronoid process
- Result in joint incongruity
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What animals are most likely to present with UAP?
large breed dogs (GSD)
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What is UAP?
no fusion of anconeal process after 150 days old
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How is UAP best diagnosed?
irregular radiolucent line between anconeal process and proximal ulna on flexed lateral radiographs
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What are radiographic signs of humeral condyle OCD?
concave radiolucent defect on medial humeral condyle on the craniocaudal projection
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What are the 3 common sites for OCD in the equine tarsus?
- medial malleolus of tibia
- lateral trochlear ridge of the talus
- intermediate ridge of the distal tibia
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What is the most common cause of elbow dysplasia in dogs?
- fragmented medial coronoid process
- medium to large breed dogs
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How is FMCP diagnosed?
- rule out UAP and OCD first
- it is very hard to see fragmented coronoid radiographically
- CT is useful
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What are radiographic signs of FMCP? (5)
- blunting of coronoid on lateral projection (superimposed on radial head)
- rounding of coronoid on craniocaudal view
- joint incongruity- widened humeral-ulnar joint, slightly widened humeral-radial joint
- DJD
- subtrochlear sclerosis
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Describe the process of aseptic necrosis of the femoral head.
- some insult causing loss of blood supply to the femoral head/ epiphysis
- articular cartilage growth continues (without ossification)
- revascularization
- incomplete removal of necrotic bone
- invasion of granulation tissue
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What are radiographic findings of avascular necrosis of the femoral head?
- [varies with duration]
- early- linear lucencies
- flat, irregular epiphysis and metaphysis
- apparent joint space widening
- muscle atrophy and DJD
- eventually, lysis of the femoral head and neck
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Describe panosteitis and its most common signalement.
- self-limiting bone disease
- more common in males
- GSDs
- 5-12 months old
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What are radiographic findings with panosteitis? (2)
- increased intramedullary bone opacity (solitary, multifocal- often near nutrient foramen)
- +/- smooth periosteal reaction
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What are 3 self-limiting bone diseases?
- panosteitis
- hypertrophic osteodystrophy
- cranial mandibular osteopathy
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What is the most common signalment for hypertrophic osteodystrophy?
- large and giant breed dogs
- 2-7 months of age
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How do dogs present with hypertrophic osteodystrophy? (7)
- systemic illness
- possibly related to distempter virus
- fever, diarrhea, leukocytosis, anemia, pneumonia
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How is hypertrophic osteodystrophy treated?
- the bone disease is self-limiting
- supportive care for diarrhea, anemia, etc signs
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What are radiographic signs of hypertrophic osteodystrophy? (3) What bones do we most commonly see this in? (3)
- transverse, lucent lines in the metaphysis= "double physis sign"
- irregular periosteal bone around the metaphysis
- +/- regional soft tissue swelling
- most common in distal radius, ulna, and tibia
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Describe craniomandibular osteopathy.
- irregular bony proliferation along the mandible +/- base of the skull
- may bridge the TMJ and cause pain on opening mouth--> stops eating
- self-limiting, supportive care if not eating
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What are the types of secondary hyperparathyroidism? (2)
- nutritional: calcium deficient or Ca/Ph imbalance
- renal: chronic renal disease leads to systemic calcium deficiency
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What are radiographic signs of secondary hyperparathyroidism? (3)
- generalized decreased bone opacity
- thin cortices
- prone to pathologic fractures
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What is a good body location to radiograph when looking for secondary hypoparathyroidism?
skull radiographs; teeth mineral is not resorbed as much so you can compare mandible and teeth, whereas in the axial skeleton, all the bones will be affected similarly and you won’t see the major differentiation
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What are radiographic signs of rickets (vit D deficiency)? (2)
- widening of the physes (dysplasia of the metaphysis)
- decreased opacity of bones
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What is disuse osteopenia?
resorption of bone because of decrease or lack of stress on that bone
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What are radiographic findings with disuse osteopenia? (3)
- decreased bone opacity
- thin cortices
- coarse medullary cavity
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Metaphyseal dysplasia is __________ and can lead to ___________.
retained cartilage core of physis; angular limb deformity
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What types of patellar luxation are common in large and small dogs?
- Medial: small and toy breeds
- Lateral: large breeds
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What is the hallmark radiographic sign of laminitis?
thickened dorsal hoof wall (usually thicker distally than proximally with laminitis)
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What measurements do you take when evaluating a radiograph for laminitis? (3)
- thickness of dorsal hoof wall (proximal thickness and distal thickness)
- length of P3
- dorsal hoof wall thickness divided by length of P3: ratio 25% or less is normal; 30% or greater is laminitis
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What abnormalities are seen with premature closure of the distal ulnar growth plate? (3)
- valgus deformity of the distal radius
- cranial bowing of the distal radius
- supination torsion
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What surgical method can be used for treatment of PCDUP?
medial transphyseal bridging of the radius and release of the ulna
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Describe hip dysplasia.
- inherited
- usually bilateral
- minimum age to evaluate coxofemoral joints to certify hips= 24 months, PennHip 4 months
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What are radiographic signs of hip dysplasia? (4)
- coxofemoral subluxation (<50% of femora head in acetabulum)
- shallow acetabulum
- osteophytes of acetabulum and/or femoral neck- DJD
- thigh and gluteal muscle atrophy
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