MSK 2

Question 1

What are the five toxic conditions of bone pathology?

Answer 1

1. Fluorosis (chronic fluoride toxicity)
2. Lead toxicity
3. Vitamin A toxicity
4. Vitamin D toxicity
5. Other (Verratrum californicum)

Question 2

What leads to fluorosis?

Answer 2

Chronic ingestion of excess fluoride (chronic fluoride toxicity)

Question 3

What is the bone lesion called in fluorosis?

Answer 3

Osteofluorosis (periosteral new bone formation/periosteal hyperostosis)

Question 4

When is the only circumstance where dental lesions with fluorosis can occur?

Answer 4

If there is a toxicity in the animal during tooth development (young animals)

Question 5

Why are teeth with fluorosis more prone to chip fractures?

Answer 5

Because of the chalky, less mineralized consistency of teeth, there is accelerated wear

Question 6

What lesions does fluorosis cause in older animals?

Answer 6

Bone lesions only (no longer developing teeth, so no dental lesions)

Question 7

What type of lesion does lead toxicity cause? What is this an example of?

Answer 7

A ‘lead line’. It is an example of a growth retardation lattice

Question 8

What is a lead line?

Answer 8

A band of sclerosis within the metaphysis of developing bones

Question 9

What is the difference between a growth arrest line and a growth retardation lattice?

Answer 9

A growth arrest line is a reduction in longitudinal growth caused by debilitating disease or malnutrition.
A growth retardation lattice is a failure of trabecular modelling caused by impaired osteoclast function due to lead toxicity or viral infection.

Question 10

What are the three causes of Vitamin D toxicity?

Answer 10

1. Accidental overdose in diet
2. Consumption of cholecalciferol rodenticides
3. Consumption of plants high in Vitamin D

Question 11

What are the three routes of infection to the bone?

Answer 11

1. Direct implantation
2. Extension from adjacent soft tissues (periodontitis or severe otitis media)
3. Hematogenous (septicemia or bacteremia)

Question 12

What is the medical term for inflammation of the periosteum?

Answer 12

Periostitis

Question 13

What are three main features of capillaries in bone? Why are these features important?

Answer 13

1. Hairpin loops
2. Fenestration of endothelium
3. Slow blood flow in sinusoidal system

Because of these three features, bacteria are more likely to lodge and colonize here.

Question 14

In young, growing animals, where does bacteria tend to localize in the bone and why?

Answer 14

Bacteria like to localize in the metaphysis of bone due to unique features of the microanatomy.

Question 15

What is the classic veterinary example of bacterial osteomyelitis? What bacteria causes this?

Answer 15

Lumpy jaw in cattle. It is caused by Actinomyces bovis.

Question 16

Infection of the jaw results in big necrotic tracts of which type of inflammation?

Answer 16

Pyogranulomatous inflammation

Question 17

What are the four most important fungal species?

Answer 17

1. Blastomyces dermatitidis
2. Cryptococcus spp (neoformans and gatii)
3. Coccidioides immitis
4. Histoplasma capsulatum

Question 18

What type of inflammation do fungal bone infections cause? What would you see histologically?

Answer 18

Pyogranulomatous to granulomatous inflammation. You’ll see macrophages, +/‐ neutrophils, and intra-lesional fungal organisms on histology.

Question 19

What leads to the development of growth retardation lattices?

Answer 19

Several viruses or toxins attack osteoclasts and inhibit or stop their activity.

Question 20

What is the medical term for excessive bone formation?

Answer 20

Hyperostosis

Question 21

What is hypertrophic osteopathy?

Answer 21

Hyperostosis (excessive bone growth) of limb bones

Question 22

What is metaphyseal osteopathy?

Answer 22

Suppurative osteomyelitis (occurs in young, large breed dogs)

Question 23

What is hypertrophic osteopathy characterized by?

Answer 23

Periosteal new bone formation

Question 24

What other illnesses is hypertrophic osteopathy associated with (two)?

Answer 24

It is associated with chronic inflammation or neoplasia within the thoracic cavity.

Question 25

Benign masses end in __________ and malignant masses end in __________.

Answer 25

'‐oma' and '‐sarcoma'

Question 26

What is the difference between primary and secondary bone tumours?

Answer 26

Primary bone tumours arise in the bones and secondary bone tumours originate somewhere else in the body and metastasize to the bones.

Question 27

What is the most common primary bone tumour of dogs and cats?

Answer 27

Osteosarcoma

Question 28

True or False: Osteosarcomas is rapidly progressive, often with early metastasis to the heart.

Answer 28

False, it is rapidly progressive, often with early metastasis to the lungs.

Question 29

True or False: Osteosarcomas almost never cross a joint to involve adjacent bones.

Answer 29

True

Question 30

True or False: Chondrosarcomas almost never cross a joint to involve adjacent bones.

Answer 30

False. Chondrosarcomas can cross joints.

Question 31

In dogs, where is the specific site predilection of osteosarcomas?

Answer 31

In the appendicular skeleton. Remember: 'Away from the elbow, towards the knee.'

Question 32

What do osteosarcomas produce? What does this look like histologically?

Answer 32

A matrix of osteoid. It looks like pink lakes on histology.

Question 33

What is the key diagnostic feature of chondrosarcomas? What does this look like histologically?

Answer 33

Production of chondroid matrix (blue material under microscope).

Question 34

What is a classic example of a metastatic (secondary) bone disease in cats? What is the main neoplasm?

Answer 34

Lung‐digit syndrome in cats. The main disease is feline pulmonary adenocarcinoma (an epithelial lung tumor).

Question 35

What is a characteristic site for metastasis of the pulmonary adenocarcinoma?

Answer 35

The bones of the feet.

Question 36

What should make you suspicious of a primary lung tumour in cats?

Answer 36

Detection of digit lesions in an older cat (order thoracic radiographs to look for a primary lung tumor!).

Question 37

What is chondrodysplasia?

Answer 37

A hereditary (autosomal recessive) disorder characterized by a defect in the formation or growth of cartilage, usually leading to disproportionate dwarfism.