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42 Cards in this Set
- Front
- Back
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Bone is __% mineral with a _:_ Ca:P ratio
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90; 5:3
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Bone matrix is composed of:
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Collagen (mostly type I) - required for tensile strength
Alk Phos - Isoenzyme produced by osteoblasts |
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Cementum is
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mineralized glue between new and old bone
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Chondrodysplasia is due to abnormal __.
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Fibroblast growth factor 4
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Abnormal FGF-4 predisposes to:
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IVDD - premature degeneration of the Nucleus pulpous
DJD - d/t abnormal limb angulation |
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Chondrodysplasia in Scottish folds is weird because:
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Autosomal incomplete dominance
Heterozygotes - folded ears, short limbs, stiff gait Homozygotes - thick, stiff tails, lameness, distal limb bone proliferation |
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About osteogenesis imperfecta...
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Rare inherited defect of collagen --> fragile bones
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Pathogenesis of Osteogenesis imperfecta
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Pathogenesis: Collagen defect > brittle bones > fractures > decreased weight bearing > decreased bone mineralization/density (often difficult to separate primary from secondary lesion) difficult to diagnose, even microscopically
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Physeal dysplasia most common in __ and leads to __.
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Young large male cats
Atraumatic unilateral or bilateral slipped capital femoral epiphyses (although all physes affected) Due to persistent disorganized growth plates |
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Amelia is ___
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- absence of limb
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Spinal anomalies include:
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Spinal anomalies: lordosis = lean straighter , kyphosis = humpback , scoliosis = S
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About Vitamin A Toxicity
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a. Due to over supplementation or abnormal diet (liver)
b. Deforming cervical spondylosis in cats (rare today) c. Vitamin A is toxic to osteoclasts |
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Primary Hyperparathyroidism
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Primary - uncommon; idiopathic parathyroid hyperplasia or tumor secretes excess PTH osteoclastic bone resorption replacement with fibrous tissue and woven bone
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All about the 2ndary types of HyperPTH
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i. Renal secondary hyperparathyroidism = renal rickets, rubber jaw
Renal disease decreased phosphorus excretion and decreased activation of vitamin D “hypocalcemia” parathyroid gland hyperplasia excess PTH osteoclastic bone resorption replacement with fibrous tissue and woven bone (fibrous osteodystrophy) Young dogs - enlarged very firm maxilla Older dogs - “rubber jaw” ii. Nutritional secondary hyperparathyroidism - rare in dogs and cats Big head or bran disease of horses; metabolic bone disease of reptiles Low calcium/high phosphorus diet excess PTH fibrous osteodystrophy |
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2 types of vitamin D deficiency
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a. Osteomalacia (bone softening) - adult animals; rare
b. Rickets - growing animals; especially primates |
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Osteoporosis leads to__.
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thin trabeculae and cortices
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About FQ arthropathy
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Articular cartilage necrosis with vesicle formation
Quinolone antibiotics (such as Baytril) contraindicated in growing animals |
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About LCP DZs
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Necrosis and collapse of femoral capital epiphysis; due to ischemia
Young small breed dogs, especially terriers and poodles Necrotic bone has empty lacunae; the osteocytes are dead |
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Stages of Fracture repair (6):
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1. Hematoma
2. Inflammation 3. Granulation tissue 4. Soft callus: fibroblasts collagen osteoblasts osteoid chondroblasts cartilage 5. Hard callus >2 weeks primary callus - mineralized woven bone secondary callus - mature (lamellar) bone 6. Remodeling - months to years, return to original shape |
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What is a callus, really?
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connective tissue that bridges fracture fragments
1. Forms both inside (internal; endosteal callus) and outside (external; periosteal callus) 2. Movement and low oxygen favors chondrocyte differentiation (cartilage within callus) Cartilage within a fracture site can look histologically very scary; history is important |
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Pathologic fractures are typically due to one of the following:
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Osteogenesis imperfecta
Osteoporosis (disuse, starvation, advanced age) Metabolic bone diseases Osteomyelitis Neoplasia (lytic osteosarcoma or other tumor) |
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Complications of fracture healing:
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1. Osteomyelitis - most common in open fractures
Inflammation does not indicate infection 2. Sequestrum - necrotic bone fragment too big to be resorbed Necrotic bone has empty lacunae; the osteocytes are dead 3. Malunion - bony union in an abnormal position 4. Nonunion - repair has ceased, but only fibrous tissue bridges fragments 5. Premature physeal closure - due to trauma that injures germinal layer of physeal cartilage Distal ulnar physis in large breed dogs continued growth of radius causes bowing |
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Cartilage fibrillation
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fraying of the articular cartilage due to excessive friction and wear
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Cartilage erosion
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loss of cartilage due to excessive friction and wear
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Osteophytes
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periarticular bony proliferations
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Eburnation
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polishing and osteosclerosis of subchondral bone after the cartilage has been completely lost; literally “to become ivory like”
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Thickened joint capsule
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increased fibrous connective tissue and synovial proliferation
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Cranial cruciate rupture
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Very common; Large breed middle aged dogs
Osteophytes common, with and without repair May predispose to histiocytic sarcoma in some breeds |
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Luxating patella. All the fun stuff.
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Medial luxation most common
Shallow trochlear groove (result, not cause) plus osteophytes |
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DJD in Cats
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90% of cats over 11 years old have DJD
DJD of shoulders and/or stifles in Siamese should raise suspicion of mucopolysaccharidosis |
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Name the cells.
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Describe this bone.
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Woven and cancellous
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Describe this bone.
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Lamellar and compact.
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What's wrong with this picture? What does it lead to? What breeds are most common?
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Chondrodysplasia.
Leads to IVDD (degen of nucleus pulposus) and DJD (d/t abnormal angulation of limb) Common in Basset, Corgi, Dachshund |
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What is the significance of this cat?
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It is a heterozygotic Scottish fold. The trait is autosomal incomplete dominant and leads to chondrodysplasia
Hetero - short limb, stiff gait, fold ears Homo - thick tail, lame, periosteal bone proliferation on distal limb |
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What is this and what is its pathogenesis?
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Osteogenesis Imperfecta.
Genetic Collagen defect causing fragile bones. Collagen defect>brittle bones>fractures>decr. weight bearing>decreased bone density |
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Differentiate between lordosis and kyphosis.
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This is an example of what? How is it caused?
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Cervical spondylosis from Vitamin A toxicosis.
Caused by all liver diet or over-supplementation. The vitamin A kills the osteoclasts (which normally clean up the old bone) |
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What is this? What would it lead to and how?
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Parathyroid Adenoma.
Would cause extreme increase in PTH > Fibrous Osteodystrophy |
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Mechanism for Renal 2ndary HyperPTH
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What's the difference in FOD in an old vs. young animal?
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Young - swollen muzzle
Older - rubber jaw |
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What is the pathway for Calcium absorption?›
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