Musculoskeletal Pathology III Flashcards

1
Q

Name three cytoarchitectural changes of degeneration

A
  1. Vacuolar change
  2. Internal nuclei
  3. Whorled and ring fibres
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2
Q

What is the chronic myopathic change?

A
  • Excessive fibre size
  • fat infiltration and fibrosis
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3
Q

What is segmental necrosis?

A
  • Sarcoplasm begins to fragment
  • Fragmented cytoplasm can mineralise
  • Circulating monocytes infiltrate and mature to macrophages
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4
Q

In what animals does true muscular dystrophy occur?

A

Golden Retriever, Rottweilers

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5
Q

What is myotonia?

A

inability of skeletal muscle to relax

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6
Q

What causes malignant hyperthermia?

A

defective ryanodine receptor

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7
Q

What does malignant hyptherthermia look like?

A

fatal, produces pale, soft, ‘parboiled’ looking muscle

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8
Q

What does toxic myopathy cause?

A

causes monophasic or polyphasic necrosis

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9
Q

What is ionophore toxicity?

A

class of antibiotics used as feed additives

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10
Q

What is exertional myopathy?

A
  • ionic and physical events associated with myofibre contraction can lead to myofibre necrosis in certain conditions
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11
Q

What is bacterial myosistis?

A

fairly common in livestock, response similiary

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12
Q

What occurs when there is decreased muscle loading?

A

atrophy

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13
Q

What is cachexia

A

weakness and wasting of the body due to insufficient dietary energy

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14
Q

What causes the hypercortisolism ‘pot belly’?

A

abdominal muscle atrophy

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15
Q

What is physiological hypertrophy?

A

normal response to exercise

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16
Q

What is compensatory hypertrophy?

A

occurs due to conditions that decrease the number of working mycofibres

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17
Q

What can compensatory hypertrophy lead to?

A

fibre splitting, which reduces diffusion distance

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18
Q

What is chronic myopathic change

A
  • excessive fibre size
  • fat infiltration and fibrosis- may result in increased muscle size
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19
Q

What is dystrophic
calcification?

A

A type of mineralisation that occurs in damaged or necrotic tissue in the body

e.g Ca2+ entering the sarcolemma

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20
Q

What is an innervation based anatomic defect

failure of innervation

A

congenital defects in lower motor neurons

such as arthrogryposis

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21
Q

What is the most common genetic defect?

A

defect in the myostatin gene

Congenital muscle hyperplasia due to increased number of myofibres

22
Q

What are the most common failures of muscle development?

A
  1. Myofibrils fail to develop
  2. Congenital defects in diaphragmatic muscle
23
Q

What is myotonia?

A

inability of the skeletal muscle to relax

results in spasmodic contraction

hyperkalemic periodic paralysis in quarter horses

24
Q

What causes malignant hyperthermia?

A

defective ryanodine receptor

25
Q

What is occlusion of a major artery?

A

aortilliac thrombosis

26
Q

How does a nutritional deficiency cause muscle damage?

A

high metabolic activity of muscle makes it sensitive to free radical damage, needs antioxidants as a defence mechanism

27
Q

What is the most common nutritional deficiency?

A

Selenium

Selenium protects cells from oxidative injury

28
Q

What does muscle affected by nutritional deficiency look like?

A

Pale ‘white muscle disease’

29
Q

When are livestock most prone to ingesting toxins

A

pasture, hay or processed feed

30
Q

What is ionophore toxicity?

A

class of antibiotics used as feed alternatives

31
Q

What is exertional myopathy?

A

ionic and physical events associated with myofibre contraction leads to myofibre necrosis in certain conditions

32
Q

What is bacterial myositis?

A

fairly common in livestock, the response is similiar to response in bacterial infection anywhere else in the body

diffuse infection without an abscess

33
Q

What do endocrine diseases lead to?

A

type 2 myofibre atrophy

34
Q

What can electrolyte abnormalities cause?

A

profound weakness and myofibre necrosis

35
Q

What is the definition of a neuromuscular disease?

A

Conditions with clinical signs primarily of muscle dysfunction

36
Q

What can happen with compensatory hypertrophy?

A

Fibre splitting in order to reduce diffusion distance

37
Q

What is global necrosis?

A

Necrosis of the entire fibre

37
Q

What is segmental necrosis?

A

Necrosis of part of the muscle fibre

38
Q

What mineral usually causes necrosis of muscle fibres

A

Ca2+ which can also go on to trigger necrosis in all cell types
* as a result, muscles are prone to mineralisation

39
Q

What is an example of a disease caused by failure to innervate?

A

arthrogryposis in ruminants

severe alteration in myofibre innervation

40
Q

What does a defect in the myostatin gene cause?

A

Congenital muscle hyperplasia due to an increased number of myofibres

41
Q

What is the pathogenesis of true muscular dystrophy in dogs?

A
  • Defect in the dystrophin gene allows gaps in the sarcoplasm
  • Causes Calcium to enter the cell
  • regulated necrosis and regeneration
  • progressive cardiomyopathy and skeletal muscle wasting
42
Q

What causes fainting goats?

A

Chloride Channel defect

43
Q

What is exertional myopathy?

A

ionic and physical events that are associated with myofibre contraction that lead to myofibre necrosis
* often there is also a pre-existing condition

44
Q

What does exertional myopathy relate to in horses?

A

Equine Polysaccharide storage myopathy

45
Q

What introduces bacterial myositis?

A
  • Direct penetration from wounds
  • Haematogenous spread
  • Spread from mearby cellulitis
46
Q

What does Haemorrhagic myonecrosis look like?

A
  • Red/ black areas with gas bubbles
  • Clostridial species release toxins that are often acute, often fatal
47
Q

What does pyogenic bacteria muscle disease look like?

A
  • Localised suppurative and necrotising myosistis
  • may resolve completely or become an abscess
48
Q

What occurs in immune-mediated myositis?

A

Cytotoxic T lymphocytes damage myofibres

49
Q

What does endocrine disease lead to?

A

Endocrine disease leads to type II myofibre atrophy
* neuropathy and denervation atrophy (resulting altered fibre type pattern)

50
Q

What do electrolyte abnormalities cause?

A
  • Profound weakness, sometimes myofibre necrosis