Muscle Flashcards
When observing the horse in a PE, what are you looking for when checking the muscles?
size, shape, symmetry. look for muscle fasciculations
What does a high creatine kinase (CK) indicate?
Myonecrosis
How long does it take after an injury for CK to peak in the serum?
4-6 hours
What is the CK elevated to in horses with light training? extreme exercise? colic? rhabdomyolysis?
Light - 400-500 IU/L
Extreme - 1000-8000 IU/L
Colic - <3000 IU/L
Rhabdomyolysis - huge variation (100-100,000’s)
What are other causes besides myonecrosis in an increase in serum AST?
hemolysis, muscle, liver, and organ damage
How long does it take after an injury for AST to peak in the serum?
24 hours
Using clinical pathology skills, what is a good chemistry indicator that myonecrosis is happening?
CK remains persistently elevated
What does elevated AST with decreased to normal CK values indicate?
Myonecrosis is not continuing
What does elevated CK and AST represent?
Recent or active myonecrosis
Besides muscle necrosis, what does an increase in LDH (lactate dehydrogenase) represent?
hepatic necrosis
What urinalysis test is used to suggest myoglobinuria?
Hemastix test (must not have hemolysis or RBC in urine)
What does renal fractions excretions determine?
FEs determine electrolyte balances in blood and urine
What is the purpose of an exercise challenge test?
To see if there is a disease precipitated by exercise
When should serum CK samples be taken in an exercise challenge test?
- ) before
2. ) 4-6 after exercise
What would you typically see in serum CK values in a horse with muscle disease?
over 3x increase in CK
What will horses with muscle abnormalities show on an electromyography?
spontaneous electrical activity
What are electromyographies and nerve conduction velocities used to classify?
Whether the disease is neuropathic or myopathic
What does nuclear scintigraphy help do?
Can find areas of muscle damage, particular deep
What is sweeney?
When the suprascapular nerve is damage and causes shoulder muscle atrophy
How quickly does a denervated muscle lose mass?
2-3 weeks
What is myotonia dystrophica?
When the muscles are progressively getting mroe and more contracted with the slightest stimuli
How do you definitively diagnose myotonia dystrophica?
electromyography
What sound do you hear with EMG in a horse with myotonia dystrophica?
dive bomber sound, high frequency repetitive bursts
What treatment has been reportedto be effective in quarter horses with hyperkalemic periodic paralysis and myotonic dystrophy?
Phenytoin
What is a non-dystrophic myotonia disease?
Hyperkalemic periodic paralysis
What is the cause of HYPP?
inherited defect in the sodium channels of skeletal muscles
What are the clinical signs of HYPP?
from asymptomatic to muscle fasciculations and weakness, sweating
What are some factors to trigger symptoms of HYPP?
Stress, sudden changes, anesthesia
T/F: Exercise does not trigger HYPP clinical signs
True
T/F: you can easily diagnose HYPP due to changes to serum CK
False. barely any changes
What is the definitive diagnosis for HYPP in horses?
DNA encoding of the sodium channel to show its faultiness
How can you control HYPP in a horse?
Decrease potassium in diet and avoid increasing its levels.
What does acetazolamide do for horses with HYPP?
stabilizes BG and potassium via increased insulin secretion, so helps with K levels
What causes muscle cramping to occur?
Hyperactivity of motor units. Repetitive firing of peripheral and central nervous system
What are the dietary issues that may lead to muscle cramping?
Sodium or potassium deficiencies
What are some electrolyte abnormalities seen with muscle cramping?
hypochloremia, metabolic alkalosis with hypokalemia, hypomagnesemia,
T/F: Muscle cramping will lead to increased values CK, AST, and/or myoglobinuria
False.
How do you treat mild muscle cramps?
You don’t, self limiting
What is the inciting cause for synchronous diaphragmatic flutter? (thumps)
Hypocalcemia
What are some causes of thumps?
prolonged exercise, hypocalcemia, GI tract issues, furosemide, trauma, 1ary hypoparathyroidism
How do you treat synchronous diaphragmatic flutters?
Give IV calcium and control with supplements
What organism causes ear tick muscle cramps?
Otobius megnini
T/F: Ear tick muscle cramp cause an increase in serum CK
True. 4000-170,000 IU/L
How do you treat eat tick muscle cramps?
locally with pyrethrins.
ace can help relieve the pain
What are the two forms of nonexertional rhabdomyolysis?
Inflammatory myopathy, nutritional myopathy
What bacteria is responsible for nonexertional rhabdomyolysis?
clostridium
What are the clinical sigs for clostridial myonecrosis?
rapidly progressive tremors, ataxia, dyspnea, recumbence, coma, death (within 24 hours)
Where you see the site of infection with clostridial myonecrosis?
Recent injection sites
T/F: Serum CK and AST are definitive diagnostics for clostridial myonecrosis
False
How do you treat clostridial myonecrosis?
Aggressive specific therapy with supportive care
What organisms causes severe acute generalized rhabdomyolysis?
Streptococcus equi.
Besides muscle disorders, what else is effected with severe acute generalized rhabdomyolysis?
blood cells
How do you control the pain in a horse with rhabdomyolsis associated strep equi?
CRI lidocaine, detomidine, or ketamine
What horse breed is associated with immune-mediated polymyositis?
quarter horses
What organism is associated with IMM?
strep. equi
What is a good treatment for IMM?
corticosteroids
How would you diagnose a seasonal pasture myopathy or atypical myopathy?
Find deficiency in acyl CoA dehydrogenase, or isolate the toxic metabolite methylenecyclopropyl acetic acid (MCPA)
What organisms causes seasonal pasture/atypical myopathy?
Seeds of the Acer tree species
What are the two forms of postanesthetic myoneuropathy?
- ) localized myopathy-neuropathy
2. ) generalized myopathy
T/F: Localized myopathy-neuropathies have complicated recoveries despite treatment
False.
What can you give to prevent the break down of muscle damage in a horse with generalized anesthetic reactions?
Dantrolene
