EqMed Q2, M Dz
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EqMed Q2, M Dz
EqMed Q2 Dz
EqMed Q2, M Dz
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)
what diagnostic test can evaluate muscle tone?
what is purpose of scintigraphy?
diagnosing deep muscle disease that is not palpable
what are recommended sites for muscle biopsy?
what is a specific disorder of muscle tone?
hyperkalemic periodic paralysis
what horses get HYPP?
quarter, paint, appaloosas
descendants of QH Impressive
how does horse with HYPP present?
myotonia, muscle fasciculations, sweating and weakness
prolapsed 3rd eyelid
dyspnea if resp. muscles affected
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
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)
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)
how is HYPP managed long term?
Acetazolamide = K+ wasting diuretic
avoid diets high in K = no alfalfa, molasses
regular exercise and frequent, small meals
what is a syndrome of muscle cramping that occurs during exercise or physical exertion?
what are 4 etiologies of rhabdomyolysis?
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.
what are some findings on MDB in horse with nutritional myodegeneration?
(can also run tests that measure selenium/E levels)
what is purpose of testing GSH-Px levels?
levels will be low because it's a selenium dependent glutathione peroxidase that forms in RBCs
How many times does CK need to be increased to indicate rhabdomyolysis?
5 fold increase
what are necropsy findings suggestive of acute white muscle disease? chronic?
: coagulative necrosis, white streaks
: calcification and IM edema
what form of rhabdomyolysis is associated with fever and systemic toxemia with high mortality rate?
inflammatory - clostridial myonecrosis
: black leg, gas gangrene, malignant edema
how is clostridial myonecrosis treated?
fasciotomy (filet open tissues, debride and aerate)
which horses get recurrent exertional rhabdomyolysis or "tying up"?
thoroughbreds (autosomal dominant trait)
what are some predisposing environmental triggers for tying up?
>2kg of sweet feed per day
exercise duration/intensity and exercising while lame
what are clinical signs of RER?
severe cramping of hindlimb muscles
sweating, anxiety, tachycardia, tachypnea
some become recumbent if severe enough
what will MDB reveal with episode of RER?
very high CK >100,000; elevated AST
azotemia (beware of pigment nephropathy)
what are diagnostic findings on muscle biopsy with RER?
more centrally located nuclei (should be peripheral)
but normal glycogen staining
how is acute RER treated?
IV fluids to avoid renal damage from myoglobin
NSAIDs with caution
sedative/tranquilizers to reduce anxiety and pain
what is involved in long term management of RER?
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
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
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
what is needed for definitive diagnose of PSSM? what are expected results?
biopsy semimem/semitendinous muscle
abnormal glycogen staining using PAS
what is a horse with PSSM's ability to synthesize glycogen?
increased ability and increased sensitivity to insulin
glycogen branching synthase 1 deficiency
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*
what are the two types of post anesthetic myoneuropathy?
malignant hyperthermia = systemic
what is etiology of post general anesthesia myoneuropathy?
what is "thumps"?
synchronous diaphragmatic flutter in horses suffering fluid/electrolyte imbalance
how does metabolic alkalosis lead to synchronous diaphragmatic flutter?
causes hypocalcemia because it promotes binding of Ca to proteins (decr. ionized calcium)