EqMed Q2, M Dz

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  1. what are two enzymes that elevate with muscle injury? which has shorter half life/rises first?
    • CK (quick to rise and 2hr half life; very sensitive for mm damage)
    • AST (peaks 12-24 hr after injury; present for 7-10d)
    • (LDH not specific)
  2. what diagnostic test can evaluate muscle tone?
  3. what is purpose of scintigraphy?
    diagnosing deep muscle disease that is not palpable
  4. what are recommended sites for muscle biopsy?
    • semimebrinous
    • middle gluteal
    • biceps femoris
  5. what is a specific disorder of muscle tone?
    hyperkalemic periodic paralysis
  6. what horses get HYPP?
    • quarter, paint, appaloosas
    • descendants of QH Impressive
  7. how does horse with HYPP present?
    • myotonia, muscle fasciculations, sweating and weakness
    • prolapsed 3rd eyelid
    • dyspnea if resp. muscles affected
  8. what is the physiologic problem that causes HYPP?
    point mutation in the Na channel of skeletal muscle - excess influx of Na/efflux of K so too close to threshold - persistent depolarization of muscle
  9. Can you test a horse for the genetic mutation associated with HYPP?
    • yes, DNA test is definitive (phenylalanine to leucine substitution)
    • electromyography can reveal evidence of HYPP
    • (inducing signs w/oral KCl is not recommended)
  10. If a horse exibits signs of acute episode of HYPP, what should you do?
    • drive potassium back into cells using *Karo syrup or IV dextrose*
    • OR elevate threshold potential with *Calcium* (so harder to cause action potential even w/ the present excess K)
  11. how is HYPP managed long term?
    • Acetazolamide = K+ wasting diuretic
    • avoid diets high in K = no alfalfa, molasses
    • regular exercise and frequent, small meals
  12. what is a syndrome of muscle cramping that occurs during exercise or physical exertion?
  13. what are 4 etiologies of rhabdomyolysis?
    • nutritional
    • inflammatory (clostridial)
    • exertional
    • traumatic (post-anesthesia)
  14. what is common name for nutritional rhabdomyolysis? what is deficient in the diet?
    • white muscle disease
    • deficient vitE or selenium
    • affects skeletal and cardiac muscle; <1 yr old usu.
  15. what are some findings on MDB in horse with nutritional myodegeneration?
    • elevated CK/AST
    • myoglobinuria
    • (can also run tests that measure selenium/E levels)
  16. what is purpose of testing GSH-Px levels?
    levels will be low because it's a selenium dependent glutathione peroxidase that forms in RBCs
  17. How many times does CK need to be increased to indicate rhabdomyolysis?
    5 fold increase
  18. what are necropsy findings suggestive of acute white muscle disease? chronic?
    • acute: coagulative necrosis, white streaks
    • chronic: calcification and IM edema
  19. what form of rhabdomyolysis is associated with fever and systemic toxemia with high mortality rate?
    • inflammatory - clostridial myonecrosis
    • aka: black leg, gas gangrene, malignant edema
  20. how is clostridial myonecrosis treated?
    • aggressive penicillin
    • fasciotomy (filet open tissues, debride and aerate)
    • laminitis prophy
  21. which horses get recurrent exertional rhabdomyolysis or "tying up"?
    • thoroughbreds (autosomal dominant trait)
    • 67% females
  22. what are some predisposing environmental triggers for tying up?
    • >2kg of sweet feed per day
    • exercise duration/intensity and exercising while lame
  23. what are clinical signs of RER?
    • severe cramping of hindlimb muscles
    • sweating, anxiety, tachycardia, tachypnea
    • some become recumbent if severe enough
  24. what will MDB reveal with episode of RER?
    • very high CK >100,000; elevated AST
    • myoglobinuria
    • azotemia (beware of pigment nephropathy)
  25. what are diagnostic findings on muscle biopsy with RER?
    • more centrally located nuclei (should be peripheral)
    • but normal glycogen staining
  26. how is acute RER treated?
    • IV fluids to avoid renal damage from myoglobin
    • NSAIDs with caution
    • sedative/tranquilizers to reduce anxiety and pain
  27. what is involved in long term management of RER?
    • daily exercise
    • minimize stress/use Acepromazine as needed
    • low carbs/high fat (corn oil/rice bran for more calories)
    • give dantrolene (muscle relaxer) as preventive treatment before exercise
  28. What is monday morning sickness? what horses are affected?
    • polysacharide storage myopathy = glycogen storage disorder, store glycogen and polysaccharide in myocytes
    • QH, paints, drafts, warmbloods
  29. if horse has persistently elevated CK/AST, even at rest, what are expected findings with an exercise challenge if he has PSSM?
    at least a 3fold increase in CK within 4-6 hours of exercise
  30. what is needed for definitive diagnose of PSSM? what are expected results?
    • biopsy semimem/semitendinous muscle
    • abnormal glycogen staining using PAS
  31. what is a horse with PSSM's ability to synthesize glycogen?
    • increased ability and increased sensitivity to insulin
    • glycogen branching synthase 1 deficiency
  32. how is PSSM managed?
    • do not confine to stall; plan exercise routine
    • decrease CHO, incr. fats
    • *diet alone is not enough, must combo with exercise*
  33. what are the two types of post anesthetic myoneuropathy?
    • malignant hyperthermia = systemic
    • localized
  34. what is etiology of post general anesthesia myoneuropathy?
    • hypoperfusion/ischemia
    • PaO2 <60mmHg
  35. what is "thumps"?
    synchronous diaphragmatic flutter in horses suffering fluid/electrolyte imbalance
  36. how does metabolic alkalosis lead to synchronous diaphragmatic flutter?
    causes hypocalcemia because it promotes binding of Ca to proteins (decr. ionized calcium)
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EqMed Q2, M Dz
2013-04-10 02:41:54
EqMed Q2 Dz

EqMed Q2, M Dz
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