Development/metabolic Bone Dz Flashcards Preview

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Flashcards in Development/metabolic Bone Dz Deck (19):
1

Osteopetrosis

"-petrosis" = thickening --> diffuse osteosclerosis

-hereditable abnormal osteoclast resorption
--> Primary trabeculae w/ cartilage filled cores in medullary cavity --> obliteration of medullary cavity

2

Osteogenesis Imperfecta

-hereditary mutant Type 1 collagen --> osteopenia
- Dachshund : SERPINh1 gene --> lack of collagen stabilization

-reduced trabecular bone (lack of O-clast activity)
-Woven bone in cortex (delayed compaction

**Teeth = PINK (disorganized dentin)

3

Congenital cortical Hyperostosis

-Disorganized of perichondral ossification grove
--> woven bone perpendicular to long axis of bone

-Neonate pigs

4

Craniomandibular osteopathy

-hereditary thickening of periosteal woven bone in Mandible, Occipital, & Temporal bones

--> Osteoblast prolif --> Trabecular Osteo-sclerosis
-Cortical bone = Thick woven bone + lamellar

-Autosomal recessive = Westies

5

Chondrodysplasias

-Hereditary disorder of Growth plates
- Trabecular bone thickened w/ lateral bridging
- Retained cartilage cores

1. Short-leg, normal head-size
-Basset, Dachshund, Pekingese
-FGF4 mutation

2. Primordial Dwarfism (proportional reduction)
-Mini schnauzers, Min Pins, Miniature poodles

3. Spider Lamb
-mutant FGFR3--> mutant Tyrosine kinase --> lack of inhibition of chondrocyte prolif
-multiple 2ndart centers of ossification in epiphysis

6

Osteochondrosis

-Delay of endochondral ossification
--> retention of growth cartilage OR articular epiphyseal cartilage necrosis

-Always vascular insult
-Other factors contribute:
-rapid growth
-Co deficient
-trauma

- all species --in long bones!
- Cattle: distal talus

7

Pathogenesis of Osteochondrosis

Ischemic necrosis AEC around necrotic vessels (osteochondrosis LATENT) --Trabeculae normal

--> failure of endochondral ossification

--> retention of necrotic epiphyseal cartilage (osteochondrosis MANIFESTA)--myelofibrosis & modeling

--> traumatic clefting through the area of necrosis (osteochondrosis DISSECANS) or replacement of necrotic cartilage by subchondral bone

8

Osteochondrosis manifesta

retention of necrotic epiphyseal cartilage

9

Osteochondrosis dissecans

Cleft formation of necrotic cartilage in Young pigs
--> separation of overlying articular cartilage
--> detachment --> JOINT MOUSE --> degenerative joint dz

Articular Epiphyseal cartilage:
-fibroplasia
-neovascularized
-remodeled

Trabecular bone:
-Fibrosis & woven bone at base of flap

10

Epiphysiolysis

Epiphysis / Metaphysis separate due to abnormal physis
-Trabeculae --> myelofibrosis, woven bone & hemorrhage

Common locations:
Pigs --Femoral head, ischial tuberosity
Dog --Anconeal process
Cats --Femoral head

11

Cervical Stenotic Myelopathy

aka Wobblers
Osteochondrosis of cervical vertebrae --> narrowed spinal canal --> spinal cord compression --> neuro dz in HORSE / Giant breed DOGS

1. Cervical Vertebral Instability
- Dynamic stenosis
- C3-4 & C4-5
- 6-15 mo Horses

2. Cervical Static Stenosis
- C5-6 & C6-7
- 1-4y Horses

12

Osteoporosis ( causes )

Increased O-clasts & decreased O-blasts --> Reduced bone density --> fractures
(thin trabeculae and cortical bone)


Cause:
-Ca deficiency (hyper-PTH)
-starvation
-physically inactive
-hypogonadism
-chronic glucocorticoid
-menopause

13

Estrogen effects on bone

Anabolic
- Increases TGF beta
- Inhibits TGF alpha, IL1, IL6 --> bone formation

14

Rickets
(what is it called in adults?)

Osteomalacia
-failure to mineralize bone

Cause:
1. Vit D/ Phos deficiency
2. Chronic renal dz
3. Fluorosis

- Diffuse irregular thickening of growth plate
- Unmineralized Osteoid in trabeculae and cortex

-sometimes in conjunction w/ Fibrous Osteodystrophy

15

Fibrous Osteodystrophy

Extensive O-clast resorption replaced by primitive fibro-osseous tissue

Trabeculae
- replaced by woven bone & Fibrous CT
- numerous Oclasts
Cortical
-Resorption
-Fibrosis

Cause:
-Hyperparathyroidsm (nutritional / renal)
- bran (horse)
- cereal grain (pig)
- all meat rations (dog)

16

Vitamin D Toxicity

Acute Overdose (increase intestinal absorb, Oclast)
-Widespread soft tissue mineralization

Chronic (suppression of bone resorption)
-Osteosclerosis
-abnormal bone matrix

17

Vitamin A Toxicity

Found in Retinoids --Sweet potatoes and raw liver

Growing animals: (Toxic to chondrocytes, Oblasts)
- Premature growth plate closure
- osteoporosis
- fractures

Adults: (stimulatory in Oblast)
- Osteosclerosis
- Periosteal bone formation

-Soft tissue mineralization

18

Lead Toxicity

Toxic to Oclast--> Osteosclerotic band of bone (parallel to growth plate) = Metaphyseal Lead Lines

19

Fluoride Toxicity

Low levels --> Oblast stimulation + hydroxyapatite w/ fluoride (resistant to Oclasts) --> Osteosclerosis

High levels --> Oblast injury --> Osteopenia and periosteal bone formation