PRACTICAL: MSK pathology, imaging and diagnostics

Question 1

Appearance - normal joint fluid

Answer 1

• small volume
• clear straw coloured
• viscous b/w fingers d/t HA
• fluid shouldn’t clot but will form gel if left to settle

Question 2

Why do you tend to see neutrophilic inflammation in the horse?

Answer 2

usually with infxn following a penetrating wound. If cell #s are very low, then acute local trauma may also be considered.

Question 3

Tx- septic arthritis (EQ)

Answer 3

• BS AB 4-6 wks
• examine area for wound
• consider contrast rads. to determine if communication b/w wound and joint (remember joint sampling)
• infected joitns should be sx lavaged ASAP to facilitate good recovery and return to work

Question 4

Can infectious diseases show PA?

Answer 4

Yes - test for tick bourne diseases (Ehrlichia, Borrelia)

Question 5

If you suspect RA, what test do you run?

Answer 5

ANA titres

Question 6

T/F: sometimes with degenerative arthropathies, no cytologic changes are seen

Answer 6

True

Question 7

What are commonest sites for OSA?

Answer 7

“away from the elbow and close to the knee”

• proximal humerus and distal radius
• distal femur and proximal tibia

Question 8

How is OSA an unusual sarcoma?

Answer 8

it doesn’t spread in bone from its original location, instead it spreads to the thorax (can and readily do metastasise here)

Question 9

Microscopic appearance - OSA

Answer 9

• extreme cellularity
• pink osteoid b/w cells
• mitotic figures

Question 10

Action for CCLR

Answer 10

• weight management
• exercise
• I/a steroids
• NSAIDs
• neutraceuticals
• sx stabilisation: intra-articular, extra-capsular or osteotomy techniques

Question 11

Outline relationship b/w exercise and OCD

Answer 11

not thought that exercise causes OCD per se but once OCD starts, exercise does exacerbate it

Question 12

Actions - OCD

Answer 12

• radiograph contralateral area
• Tx - arthroscopy and debridement of subchondral bone bed and remove cartilage flap (if present)
• conservative (exercise restriction and analgesics) although less successful than sx

Question 13

Define AE complex

Answer 13

Articular- epiphyseal complex

Question 14

T/F: cartilage thickness varies normally across a joint d/t different pressure gradients

Answer 14

True

Question 15

List radiographic signs of laminitis

Answer 15

• gas showing separation of laminae
• P3 rotation
• foundering (P3 sinking)
• hoof wall separation

Question 16

What may fill a space b/w detached epidermal laminae of inner hoof wall and dorsal surface of P3?

Answer 16

• proliferated epithelium
• necrotic tissue
• areas of inflammation

Question 17

What happens to the outer hood in laminitis?

Answer 17

• shape of weight bearing surface of hoof changed
• external surface of horny sole altered
• turning up and irregular wear of toe region and thickening of the heel of the horny side

Question 18

Radiographic signs - hypertrophic pulmonary osetopathy

Answer 18

• THORAX: nodular interstitial pattern consistent with pulmonary neoplasia
• BONE: irregular periosteal new bone formation along the diaphyses of the long bone

Question 19

Another name - hypertrophic pulmonary osteopathy

Answer 19

Marie’s disease

Question 20

If primary lesion of marie’s disease is removed, will the bone lesions regress

Answer 20

Yes lesions may regress

Question 21

Describe marie’s disease

Answer 21

Periosteal new bone growth occurs on distal limb bones in association with a chronic, usually intrathoracic, inflammatory or neoplastic lesion.
- Pathogenesis unknown but theories include reflex vasomotor changes mediated by vagus increasing blood flow to extremities (periosteal oedema and hyperaemia then cause new bone growth)

Question 22

Cause - White mm disease (WMD)

Answer 22

= a nutritional myopathy

• d/t Se and vitamin E deficiency
• usually FA/ruminants on deficient pasture

Question 23

Dx - WMD

Answer 23

• mm biopsy (more expensive method): shows high # macrophages removing debris of degenerate mm fibres
• CK and AST blood levels (cheaper)