Vet Path B 250-215 Bone Pathology L3 L4

Front 1

metabolic bone disease
- aka
- caused by

Back 1

Osteodystrophy

Nutritional or hormonal imbalances

Front 2

Metabolic bone disease

4 main types

Back 2

Osteoporosis (osteopenia)

Fibrous osteodystrophy

Rickets

Osteomalacia

Front 3

Hormones affecting bone growth

Back 3

Corticosteroids
GH & IGF-I
Thryoid hormone
Sex steroids

Front 4

Increased corticosteroids
- affect on bone

Back 4

Osteoporosis dt decr rate of bone formation

Front 5

Decreased GH & IGF-I
- affect on bone

Back 5

Proportional dwarfism
- progenitor cell differentiation
- chondrocyte proliferation

Front 6

Hyopothyroidism
- affect on bone

Back 6

Neonatal mortality

Postnatal exposure: retarded growth

Front 7

Hyperthyroidism
- affect on bone

Back 7

Osteoporosis prob dt negative metabolic balance

Front 8

Sex steroids
- affect on bone

Back 8

Osteoblasts have both estrogen & progesterone receptors

Hypoestrogenism > osteoporosis (menopause)

Front 9

Define osteoporosis & osteopenia

Back 9

Osteopenia: reduced mass of normal quality bone tissue (can be clinically silent)

Osteoporosis: reduced mass of normal bone quality OF CLINICAL SEVERITY

Front 10

5 general causes of osteoporosis

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1. Starvation - protein/calorie malnutrition
2. Gastrointestinal parasitism
3. Specific deficiency
4. Disuse atrophy
5. Endocrine associated osteoporosis

Front 11

4 specific deficiencies that can lead to osteoporosis

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- calcium
- phosphorus
- copper
- vitamin C

Front 12

Osteoporosis from most causes is due to impaired deposition of bone
- except for which two causes?

Back 12

Disuse atrophy and calcium deficiency lead to ACCELERATED RESORPTION of bone and thus osteoporosis

Front 13

Histology of osteoporotic bone
- what feature indicates whether dt increased resorption or decreased production of bone?

Back 13

Less trabeculae if increased resorption

Normal no. of thin trabeculae if decreased production

Front 14

2 main consequences of osteoporosis

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Pathological fractures & epiphyseal separation

Hypocalcaemic crises
- weaned lambs
- lactating ewes

Front 15

What are you seeing

Back 15

Osteoporotic bone with thinned and porous cortices

Front 16

What might you see in an osteopenic bone during starvation or specific mineral deficiencies?

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Serous atrophy of marrow
Metaphyseal growth arrest lines
Widely spaced trabeculae

Front 17

Why, in some circumstances, doesn't osteoporotic bone return to normal when nutrients balance resumes?

Back 17

Trabeculae surfaces are required for the formation of new bone by apposition

Front 18

What are common sites of epiphyseal separation (4)

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Femoral head
Humeral head
Ischial tuberosity
Vertebrae

Front 19

How does copper deficiency lead to osteoporosis?

Back 19

Copper is required for adequate production of matrix collagen

Front 20

What causes fibrous osteodystrophy

Back 20

Prolonged and excessive exposure to PTH

Front 21

What is the aetiology of fibrous osteodystrophy

Back 21

Prolonged & excessive PTH ->

Increased osteoclastic resorption (>porosity), AND

Proliferation of osteoprogenitor cells to produce excess fibrous and fibro-osseus tissue

Front 22

List the 4 sources of increased PTH secretion

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Tumours of the PTH gland (rare)

Paraneoplastic secretion of PTH-like hormone by malignancies (lymphoma, anal gland tumour)

Secondary nutritional hyperparathyroidism

Secondary renal hyperparathyroidism

Front 23

How can secondary nutritional hyperparathyroidism occur?

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Occurs in response to relative Ca deficiencies (ratio Ca:P = 1:1)
- diet low in Ca, high in P (ratio imbalance)
- bran is high in P (horses)
- carnivores on offal (high P)

Front 24

How does secondary renal hyperparathyroidism occur?

Back 24

Renal failure leads to

- failure to excrete P (thus depression of Ca)

- reduced synthesis of active VitD

Front 25

This horse was fed a diet in bran. What is this disease and cause?

Back 25

Nutritional fibrous osteodystrophy ("Bighead" or "bran disease")
Bran high in P, Ca:P imbalance, PTH oversecretion, increased deposition of fibrous material in bone

Front 26

Some tropical grasses can lead to fibrous osteodystrophy. How?

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High in oxalates which band Ca++ in the gut and prevent absorption leading to hyperparathyroidism

Front 27

Osteomalacia

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Softening of bone (can be cut with a knife) dt deficiency of phosphrous or of vitamin D -> failure of bone matrix to mineralise

Front 28

Rickets

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Deficiency of phosphrous or of vitamin D -> failure of cartilage AND bone matrix to mineralise

Front 29

How are osteomalacia and rickets similar and different

Back 29

Both are dt vit D or P deficiency
- Osteomalacia: bone affected
- Rickets: cartilage AND bone fail to mineralise

Osteomalacia is aka adult rickets

Front 30

What are the two main causes of osteomalacia in cattle & sheep?

Back 30

VitD deficiency in pastured animals where winter sun is low on the horizon (sheep more susceptible)

Phosphorous deficiency dt grazing deficient pastures (uncommon: cattle more susceptible)

Front 31

List 4 sequential changes in rickets

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1. Failure of mineralisation & vascular invasion of the hypertropic zone

2. Failure of replacement of the growing cartilage with woven bone

3. Formation of osteoid (not bone) on persistent cartilage with irregular osteochondral junctions

4. Metaphyseal compression fractures with fibrosis & deformities of the shape & structure of bone

Front 32

What is the simplest and earliest anatomic manifestation of rickets

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Widening of the physis

Front 33

What condition is this most likely to be? What processes can be seen?

Back 33

Front 34

What's this? Why?

Back 34

Rachitic rosary

Enlarged joints at the costo-chondral junctions.

Front 35

What are the causes of rickets in calves, sheep, pigs, puppies & kittens and Alpaca crias?

Back 35

Calves: P-deficient pastures, sunlight deficiency

Young sheep: sunlight deficiency, green feed low in VitD

Pigs: sunlight deficiency, VitD deficiency (feed errors), insufficient activation of VitD in kidney

Puppies & kittens: same as pigs

Crias: common bouts of severe GI disease -> electrolyte loss (Ca & P)

Front 36

What is florid rickets?

What is it commonly seen in pigs?

Back 36

"Florid" = quick, flamboyant

Occurs in pigs as they are frequently weaned early and the grow rapidly

Front 37

What animal species is mostly affected by osteomalacia?

Back 37

?

Front 38

What is scurvy?

Back 38

Vitamin C deficiency in animals requiring an exogenous source (guinea pigs, primates)

Front 39

What is the aetiology of scurvy?

Back 39

Vit C required for collagen formation

Thus failure of osteoid formation

Cartilage calcification is unaffected leading to a distinctive line of calcified cartilage spicules without newly formed osteoid "SCORBUTIC LATTICE"

Front 40

Review physis biology

Back 40

Front 41

Causes of toxic osteodystrophies (3)

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Fluorosis

VitD toxicity

VitA toxicity

Front 42

Fluorosis
- how?
- who's affected?
- What's affected?
- CS?

Back 42

Chronic exposure to excess fluoride leading to lack of mineralisation of teeth and bones

Herbivores

Teeth (toxic to odontoblasts) & bones (toxic to osteoblasts)

Teeth: mottling enamel, rapid wear, chipping
Bones: compensatory periosteal bone formation -> shifting lameness. Also spontaneous fractures

Front 43

VitD toxicity
- 3 sources
- increased by?

Back 43

Dietary supplementation
Plants
Rodenticides

VitD toxicity increased with high dietary levels of calcium

Front 44

VitD toxicity
- acute responses

Back 44

Hypercalcaemia & hyperphosphatemia (dt incr osteoclast activity initially)

Metastatic mineralisation of soft tissue

Renal failure

Front 45

VitD toxicity
- chronic responses

Back 45

Early: incr. osteoclast activity -> removal of primary spongiosa

Then: incr. osteoblast activity and incr mineralisation -> osteosclerosis ("hardening")

Front 46

VitA
- role in bone

Back 46

Stimulate osteoclast activity

Front 47

VitA deficiency
- causes in LA & SA

Back 47

Cattle, pigs: unsupplemented rations or old hay

Carnivores: lean meat (no liver)

Front 48

VitA deficiency
- main effects

Back 48

Defective remodelling of membranous bone in skull & spine -> cerebellar herniation into foramen magnum

Also blindness, deafness, CNS signs

Front 49

VitA toxicity
- how?

Back 49

Esp cats fed almost exclusive diet of raw liver

Front 50

VitA toxicity
- effect on growing animals & adults

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Growing animals:
- degeneration & necrosis of chondrocytes & osteoblasts
- premature closure of growth plates, deformity, OSTEOPOROSIS

Adults
- paradoxical stimulation of osteoblasts
-> OSTEOSCLEROSIS, periosteal bone formation, exostoses, spondylosis

Front 51

Fused cervical vertebrae, cat: Name and likely cause

Back 51

Deforming cervical spondylosis: VitA toxicity

Front 52

From here on, have given a definition of each term.

Back 52

May expand later

Front 53

Osteonecrosis
- 6 causes
- 1 potential consequence of importance

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1. Inflammatory diseases
2. Infiltration neoplasma
3. Peripheral vasoconstriction
4. Emboli (gas or fat)
5. Impaired lipid metabolism

Bone infarction can lead to OSTEOSARCOMA

Front 54

Aseptic necrosis of bone
- aka ?
-cause?

Back 54

Osteonecrosis
- bone death dt ischaemia (infarction)

Front 55

Legg-Calve-Perthes disease
Which is the affected side?

Back 55

Left (avascular)

Front 56

Legg-Calve-Perthe disease
- what is it?
- who's most affected

Back 56

Avascular necrosis of the femoral head

Poodles, Westies, Yorkies

Front 57

Canine hypertrophic osteodystrophy (HOD)
- aka
- what is it?
- who's affected?

Back 57

Metaphyseal Osteopathy
Initial lesion - neutrophilic osteomyelitis of metaphysis
Young, fast-growing large breeds
Most resolve spontaneously

Front 58

Consequence of metaphyseal osteopathy?

Back 58

Subphyseal infraction

Front 59

Craniomandibular osteopathy
- aka
- who?
- what?

Back 59

Lion jaw
- terriers (4-7mo)
- endosteal & periosteal proliferation of woven bone in mandible, occipital & temporal bones

Front 60

Canine panosteitis
- who?
- what?
- effect?

Back 60

Young, fast growing, large breed dogs (esp male GSD)
Inflammatory process, unknown cause
Waxes 7 wanes -> mild-severe lameness

Front 61

Marie's disease
- aka
- commonly associated with?
- effects? why?

Back 61

Hypertrophic osteopathy
Commonly assoc with a space occupying lesion of thorax (lung or chest wall) esp Spirocerca in dogs

Primarily a vascular disease leading to deposition of periosteal bone

Front 62

Osteochondritis dissecans
- who?
- aetiology

Back 62

Young, fast growing animals

Multifactorial (genetic, trauma, nutrition, excess dietary ca, cu def, hormones) but

underlying pathogenesis is ISCHAEMIC DAMAGE TO GROWING CARTILAGE

Front 63

Main histological features of osteochondrosis

Back 63

Persistence of hypertrophic cartilage at physis

Front 64

Name different types of bone tumours

Back 64

Osteoma
Ossifying fibroma
Osteosarcoma
Fibroblastic osteosarcoma
Giant cell osteosarcoma
Chondroma
Osteochondroma
Chondrosarcoma
Fibrosarcoma
Haemangiosarcoma
Plasma cell myeloma
Lymphosarcoma
Enzootic bovine leukosis

Front 65

What cells type can lead to primary neoplasms of bone

Back 65

Bone
Cartilage
Fibrous
Adipose
Vascular
Myeloid cell lineages
Lymphoid cell lineages

Front 66

Osteoma

Back 66

?

Front 67

Ossifying fibrtoma

Back 67

?

Front 68

Osteosarcoma
- frequency?
- progression

Back 68

Most common pirmary neoplasm of dogs & cats

Rapidly progressive - 14-22w survival

Front 69

Osteosarcoma
- classification

Back 69

6 histological categories
- poorly differentiated (agressive)
- osteoblastic
- chondroblastic
- fibrobalstic (last aggressive)
- telangiectatic (most aggressive)
- giant cell

Front 70

Ostesarcoma
- common sites in dogs

Back 70

Away from the elbow, towards the knee

Front 71

Name 2 cartilage forming tumours

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Chondroma

Chondrosarcoma

Front 72

Chondroma
- what?
- where?

Back 72

Benign tumour of cartilage
Mainly flat bones (scapula, ribs)
From articular cartilage?

Front 73

Chondrosarcoma
- what?
- where?

Back 73

Malignant tumour of cartilage
Arise from existing growth plate cartilage or metaplastic cartilage NOT articular cartilage

Front 74

Some more to do briefly

Back 74

Some more to do briefly