Bone pathology

Question 1

Bone tissue is formed by?

Answer 1

Cells

Osteoblasts makes

Osteocytes

Osteoclasts break

Question 2

What is the organic and inorganci components of osteoid?

Answer 2

Organic component: Osteoid

• 90% type I collagen
• 10% water, non-collagenous proteins, lipids, proteoglycans…

Inorganic component: mineralized tissue (called hydroxyapatite)

• Hydroxylated calcium phosphate

Question 3

What does loss of inorganic matrix and organic matrix mean?

Answer 3

Loss of organic matrix: Brittle bone

Loss of inorganic component: Flexible bone

Question 4

Label osteoblasts, osteoclasts and osteocytes on a histological image?

Answer 4

Question 5

Where does Endochondral ossification of long bones occur?

Answer 5

Metaphyseal growth paltes (physes)

Question 6

Where does Intramembronous ossification of flat bones occur?

Answer 6

Bone formed directly from the periosteum

Question 7

Describe bone remodelling?

Answer 7

Bone (re)modelling: Bone is deposited where needed and resorbed where not (dynamic)

Question 8

What causes alteration in bone mass?

Answer 8

Alterations in bone mass:

Systemic diseases and abnormal use may affect bone mass:

• Increase: hypervitaminosisA
• Decrease: Osteoporosis, disuse

Injured periosteum often responds by forming bone (see picture)

Question 9

Define brachycephalic?

Answer 9

shortening of the head

Question 10

Define Brachygnathia

Answer 10

abnormally short jaw

Question 11

Define Prognathia?

Answer 11

abnormal projection of the jaw

Question 12

Define Kyphosis?

Answer 12

dorsal curvature of the spinal column

Question 13

Define Lordosis?

Answer 13

ventral curvature of the spinal column

Question 14

Define Scoliosis?

Answer 14

lateral deviation of the spinal column

Question 15

Define Amelia?

Answer 15

absence of limb/s

Question 16

Define Hemimelia?

Answer 16

absence of distal limb part

Question 17

Define Polydactyly?

Answer 17

presence of supranumerary digits

Question 18

Define Adactyly?

Answer 18

absence of a digit

Question 19

Define Syndactyly?

Answer 19

fusion of digits

Question 20

Name congenital bone disorders?

Answer 20

• Chondrodysplasias
• Osteopetrosis
• Osteogenesis imperfecta
• Congenital hyperostosis
• Osteochondromatosis

Question 21

Describe chondrodysplasias?

Answer 21

Dysplasia: Disordered development

• Hereditary disorders of bone growth result of primary lesions in growth cartilage
• Defect in bones having endochondral ossification (long bones) but not in bones with intramembranous ossification (flat bones)
• Short-legged and normal-sized heads e.g Basset hound Dachshund
• Spider lamb syndrome

Question 22

What is the congenital disorder osteopetrosis?

Answer 22

• Defect in bone resorption by osteoclasts
• Although bone mineral density is increased, bones can be more fragile

Question 23

Describe metabolic bone diseases?

Answer 23

Usually systemic diseases

Common causes: nutritional, toxic or endocrine

The three main diseases are:

1. Osteoporosis
2. Rickets/Osteomalacia
3. Fibrous osteodystrophy

Question 24

Describe osteoporosis?

Answer 24

• Reduced bone mass (normal bone quality, well mineralized)
• Not commonly diagnosed in veterinary species, but can happen
• Causes: malnutrition, physical inactivity, dietary calcium deficiency, advanced age, glucocorticoid excess, oestrogen or androgen deficiency
• Consequences: Brittle bones, fractures

Question 25

Describe Rickets/osteomalacia?

Answer 25

* Failure of mineralization in growing skeleton (rickets) and adults (osteomalacia) * **Causes:** calcium/vitamin D deficiencies, phosphorus deficiency, chronic renal disease * **Consequences:** Bone deformities, thickening of growth plates and fractures

Question 26

Describe fibrous osteodystrophy?

Answer 26

Increased widespread osteoclastic resorption of bone and replacement by fibrous tissue **Causes:** * Primary hyperparathyroidism * Secondary hyperparathyroidism (renal or nutritional) * Pseudohyperparathyroidism (certain neoplasia) * Lack of UV in reptiles (the disease is usually referred as metabolic bone disease) **Consequences:** Lameness, fractures, deformities

Question 28

What can be seen here?

Answer 28

Fibrous osteodystrophy

Question 29

What can be seen here?

Answer 29

Normal bone, normal mass, Normal bone mineralisation

Question 30

What can be seen here?

Answer 30

**Osteoporosis** * Decreased bone mass * Normal mineralisation

Question 31

What can be seen here?

Answer 31

**Rickets/Osteomalacia** Reduce bone mineralisation

Question 32

What can be seen here?

Answer 32

**Fibrous osteodystrophy** * Decreased bone mass * Fibrous replacement

Question 33

Compare normal, osteoporitic, rickets/osteomalacic and fibrous dystrophic bone?

Answer 33

Question 34

Compare normal, osteoporitic, rickets/osteomalacic and fibrous osteodystrophic bone?

Answer 34

Question 35

Discuss hypervitaminosis D?

Answer 35

**Typical causes:** * Ingestion of plants calcinogenic plants (e.g. Solanum sp., Trisetum flavescens ) (herbivores) * Feed overdoses (pigs and horses) * Ingestion of certain drugs (e.g. rodenticide) * Produce hypercalcemia and/or hyperphosphatemia and consequently metastatic mineralization * Typical places of mineralization: vessels, lung, kidney and stomach

Question 36

Define Periostitis?

Answer 36

Inflammation of bone with involvement of periosteum

Question 37

Discuss scurvy?

Answer 37

Vitamin C is required for collagen synthesis Guinea pigs, some primates, and some bats cannot synthetize vitamin C **Consequences:** **Osteopenia:** bone fragility, fractures Metaphyseal, articular, muscular and subcutaneous haemorrhages

Question 38

Define osteitis?

Answer 38

Inflammation of bone

Question 39

Define Osteomyelitis?

Answer 39

Inflammation of bone with bone marrow involvement can be infectious or non-infectious in origin

Question 40

What are the routes of infection for Infectious inflammatory diseases?

Answer 40

Routes of infection: 1. Haematogenous 2. Trauma 3. Inflammation of adjacent tissues (e.g. periodontitis – maxilla/jaw, otitis –tympanic bulla)

Question 41

What are common infectious causes of inflammatory bone disease?

Answer 41

**Infectious causes:** Bacteria. * Most common. Pyogenic bacteria ( Trueperella pyogenes , Streptococcus spp., Staphylococcus spp., Escherichia coli , Salmonella spp..) Fungi * Coccidioidesimmitis , Blastomycesdermatitidis Virus * (Canine distemper virus (CDV) , Bovine viral diarrhea virus (BVDv) Haematogenous bacterial osteomyelitis is common in young farm animals and foals

Question 43

What is this?

Answer 43

Chronic pyogranulomatous osteomyelitis, Actinomyces bovis “lumpy jaw”

Question 44

What can be seen here?

Answer 44

Radius, dog, Canine distemper Growth retardation lattice

Question 45

Describe the non-infectious inflammatory disease metaphyseal osteopathy?

Answer 45

* Young dogs (2-6 months) * Usually large breeds **Presentation:** * Lameness * fever * swollen * painful metaphyses in multiple long bones * Suppurative and fibrinous osteomyelitis of the trabecular bone of the metaphysis Most cases resolve completely Unknown aetiology

Question 46

Describe the non-neoplastic proliferative lesion **Hypertrophic Osteopathy?**

Answer 46

* Dogs * Progressive, bilateral periosteal new bone formation in the diaphyses of distal limbs * Usually associated to intrathoracic neoplasms or inflammation

Question 47

Describe the non-neoplastic proliferative lesions **Craniomandibular Osteopathy** (“lion jaw”)?

Answer 47

* Hereditary condition * West Highland white terrier (WHWT) * Thickening of mandibles, occipital and temporal bones

Question 48

Discuss bone neoplasia?

Answer 48

* Malignant neoplasia more common * Imaging is highly important for diagnosis, since bone biopsies often contain reactive periosteum * Secondary (metastatic) bone tumours are rare. Mainly carcinomas. e.g. pulmonary carcinomas in cats can metastasise to digits (to the 3rd phalanx, sloughing claws)

Question 49

Create a table for primary bone neoplasms?

Answer 49

Question 50

Discuss osteosarcomas?

Answer 50

* Most common primary bone neoplasia in dogs and cats, rare in other species * Malignant neoplasm in which neoplastic cells form bone and/or osteoid * More common in medium and large breed dogs * **Most commonly:** arises from metaphysis and is close to the knee, away from the elbow * Do not affect joint * Haematogenous pulmonary metastasis is common

Question 51

What can be seen here?

Answer 51