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Flashcards in Large animal muscle disease Deck (86)
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1

List muscle diseases causing muscle pain/cramping

- Equine rhabdomyolysis syndrome (sporadic or chronic)
- Atypical myoglobinuria
- Malignant hyperthermia

2

List the muscle diseases causing muscle weakness in horses

- Muscle atrophy (disuse, neurogenic, cachexia)
- Equine motor neurone disease

3

List the muscle diseases causing collapse in horses

- Myotonia
- Hyperkalaemic periodic paralysis

4

List muscle disease in horses other than those causing weakness, collapse, or muscle pain/cramping

- Fibrotic myopahty
- Muscle rupture
- Aorto-iliac thrombosis
- Spastic paralysis
- Stringhalt
- PPID

5

List the possible clinical signs of muscle disease in large animals

- Muscle atrophy
- Muscle stiffness/pain
- Myoglobinuria
- Recumbency/collapse
- Hyperthermia
- Exercise intolerance
- Abnormal contraction
- Non-specific signs

6

What are the differentials for myoglobinuria in the horse?

- Muscle disease
- Haematuria
- Haemoglobinuria

7

Explain why hyperthermia may occur with muscle disease

- Inflammation leading to pyrexia
- May also increase heart production from contracting muscles

8

What aspects of the history are particularly relevant for investigation of muscle disease in horses

- Temperament, diet
- Occurrence: acute, recurrent, chronic
- Progression of signs
- Other diseases

9

Which parameters may be raised on biochemistry, indicating muscle disease in a large animal?

- Creatine kinase
- Aspartate aminotransferase (AST)
- Lactate dehydrogenase 5 (skeletal muscle isoenzyme)
- +/- urea

10

Explain the interpretation of creatine kinase in an animal with suspected muscle disease

- Can be cardiac or skeletal, where there are clinical signs of muscle disease can decide whether MSK
- Short half life, good for identification of acute conditions or ongoing pathology

11

Explain the interpretation of AST in an animal with suspected muscle disease

- Produced in skeletal muscle, bone, liver
- If both CK and AST are elevated can be fairly certain is due to muscle pathology
- If CK normal but AST high, may be due to longer half life (7-8days vs 2hrs) of AST but need to rule liver disease

12

Explain the interpretation of myoglobinuria in an animal with suspected muscle disease

- Suggestive of significant disease
- Is toxic to renal tubules
- In all cases need to administer fluids

13

Why might urea be elevated in muscle disease?

Concurrent renal disease

14

Outline the exercise test used where muscle disease is suspected

- Used to determine chronic recurrent pathology
- Biochemistry following 15mins mild exercise e.g. trot lung
- Normal: CK<200% increase between 2-6 hours, and AST <50% increase at 24 hours

15

Which parameters are assessed in the diagnosis of muscle disease on urinalysis?

- Myoglobinuria (urine dipstick)
- Fraction excretion of electrolyte

16

Explain the significance of fractional excretion of electrolytes in muscle disease in the horse

- May increase with recurrent rhabdomyolysis due to myoglobinuria causing damage to the renal tubules
- Generally more indicative of intracellular ions than serum measurement

17

Where are muscle biopsy samples taken from in the horse for the investigation of the different muscle disease in the horse?

- RER, PSSM: semitendinosus
- EMND: sacrodorsalis caudalis medialis
- RER: gluteal

18

Outline the assessment of muscle biopsies for the diagnosis of muscle diseases

- Confirmation of disease by assessing degeneration, necrosis and regeneration vs lysis or oedema
- Identify underlying mechanisms
- Estimate % of fibres affected

19

What advise should be given to a horse owner following a muscle biopsy?

- Likely to be uncomfortable, esp. gluteal biopsy
- Box rest will reduce use of this muscle and thus reduce discomfort perceived by the horse

20

List the diagnostic tools used in the diagnosis of equine muscle disease

- Physical examination and palpation
- Blood biochemistry
- Urinalysis
- Exercise test
- Muscle biopsy

21

What is equine rhabdomyolysis syndrome also known as?

Tying up

22

What is equine rhabdomyolysis syndrome usually precipitated by?

Exercising beyond their level of fitness

23

What are the different presentations of equine rhabdomyolysis syndrome?

- Sporadic: exertional rhabdomyolysis (exhausted horse syndrome)
- Chronic: Recurrent equine rhabdomyolysis (RER), Polysaccharide storage myopathy (PSSM)

24

Outline the clinical signs of equine rhabdomyolysis syndrome and when might these occur?

- May occur before, during or after exercise
- Exercise intolerance
- Stiff gait
- Reluctance to move
- Recumbency
- Muscle pain, hard muscles
- Myoglobinuria
- Pain - sweating, tachycardia, tachypnoea
- Hyperthermia

25

what are the potential consequences of myoglobinuria in thehorse?

- Pre-renal azotaemia: often hypovolvaemic (dehydration from intense exercise)
- Renal azotaemia: pigmenturia, damage to kidney, can be life threatening

26

When does recurrent/chronic equine rhabdomyolysis syndrome commonly occur?

- Before, during or after only light exercise
- Agitation prior to exercising

27

Describe the pathology that occurs with equine rhabdomyolysis syndrome

Lysis of muscle fibres esp type II (fast twitch) fibres

28

List the trigger factors for sporadic exertional rhabdomyolysis in the horse

- Overexertion
- Heat exhaustion
- Dietary imbalance (high non-structural carb feeding, vit E/selenium deficiency)
- Electrolyte imbalance
- Viral, immune mediated (rare - viral myositis)

29

Describe the signalment for sporadic exertional rhabdomyolysis in the horse

- No underlying muscle defect
- Any age, breed, sex

30

Outline the problems related to sporadic exertional rhabdomyolysis in the horse

- Hypovolaemia
- Hyperthermia
- Low muscle pH (high speed exercise)
- Depleted glycogen (endurance exercise)
- Impaired membrane pump function leading to electrolyte imbalances and ATP deficiency
- Increased sarcoplasmic Ca2+
- Ileus, cardiac dysrhyhmias
- Synchronous diaphragmatic flutter (thumps)