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85 Cards in this Set
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What are the 4 major categories of musculoskeletal disorders?
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(1) Abnormal electral conductions resulting in fasiculations or abnormal tone
(2) Muscle atrophy (3) Rhabdomyolysis (4) Muscle dysfunction w/normal CK |
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Usually myopathies are characterized into which three divisions?
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Exertional, non-exertional, or miscellaneous
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What are some signs to look for on physical exam for a myopathy?
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Lameness or pain
Alterations in muscle texture/tone Symmetry Atrophy Muscle response to percussion |
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How long does it take CK to peak? Elevated CK indicates damage within what time period?
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CK peaks in 4-6 hours.
Indicates damage within 3 days. |
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How long does it take AST to peak? Elevated AST indicates damage within what time period?
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AST peaks in 24-48 hours.
Indicates damage within 14 d. |
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How may significant muscle damage manifest in the urine? What is the "CK cutoff" for this?
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Myoglobinuria occurs when CK >20000.
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How high must the CK be before brown urine is seen?
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CK>40000
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Which tube type and blood fraction is best for measuring vitamin E? Selenium?
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Serum or plasma in a plain or heparin tube for vitamin E.
Whole blood in EDTA for Se. |
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When performing a muscle biopsy, should the sample be formalin fixed or frozen?
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Frozen provides better results!
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Where is a good place to take a muscle biopsy in the horse?
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Semimembranousus halfway between tuber ischii and achilles tendon
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How should normal muscle behave in electromyography?
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Minimal spontaneous activity
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Abnormal EMG can confirm:
a) myopathy b) neuropathy c) denervation d) HYPP |
a) myopathy
b) neuropathy c) denervation d) HYPP |
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What are some clinical signs of exertional rhabdomyolysis?
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Sweating
Stiff & reluctant to move fasiculations Firm muscles Brown-red urine (other non-specific signs) |
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What are the two types of exertional rhabdomyolysis?
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Chronic and Sporadic
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Which muscle fibers are affected in equine ER?
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Type II fibers
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Which drug is great for preventing further muscle damage? What is a possible side effect?
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Dantrolene (can induce hyperkalemia)
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Predict the relative electrolyte levels in a horse with exertional rhabdomyolysis.
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K and P UP
Ca, Na, and Cl DOWN |
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What are the 2 forms of chronic equine exertional rhabdomyolysis? How can they be differentiated?
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Recurrent ER
Polysaccharide Storage Myopathy (differentiate by biopsy) |
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PSSM is more common in which horse breeds?
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Drafts, QH related breeds, warmbloods
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Recurrent ER is more common in which horse breeds?
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Thorobreds, Arabs, Standardbreds
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What is the typical signalment for RER?
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Nervous 2yo thoroughbred filly
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What is the pathogenesis for RER?
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Abnormal intracellular Ca regulation
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How can RER be prevented?
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Reduce stress
Good warm-up b4 exercise Good quality grass hay Electrolyte supplement Address lameness |
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How is RER transmitted?
a) ticks b) flies c) autosomal recessive d) autosomal dominant |
d) autosomal dominant
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What is a common presentation of a draft horse with PSSM?
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Asymptomatic w/normal CK
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What is a common presentation of a QH with PSSM?
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Classic ER signs; persistent increase in muscle enzymes
Occasional epaxial wasting |
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What mutation causes PSSM in draft horses? In quarterhorses?
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Glycogen Synthase 1 mutant in BOTH (just different signs)
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How can PSSM be diagnosed?
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Genetic testing for GYS1 gene (type I)
Biopsy (type I or type II) |
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What are the two types of PSSM and how do they differ?
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Type I (has mutant GYS1 gene)
Type II (no mutated gene but positive biopsy) |
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What is seen on a positive PSSM biopsy?
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High muscle glycogen (purple)
Amylase-resistant PAS-positive inclusions Subsarcolemmal vacuolations |
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How can PSSM be managed?
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Regular exercise + low starch, high fiber, and fat supplemented diet.
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What are the categories of non-exertional myopathies of large animals?
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Inflammatory
Trauma Toxic Nutritional Metabolic Idiopathic |
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Clostridial myositis is often associated with:
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IM banamine or ivermectin
Also vaccines, furosemide, xylazine, and vitamin B acupuncture |
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What are signs of clostridial myositis?
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Rapid onset of pain (48hrs)
Fever gas pockets in affected region Tachycardia/tachypnea lame discolored membranes sometimes cool region develops |
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How can clostridial myositis be diagnosed?
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Clinical signs mostly
Ultrasonography (fluid pockets, gas, edema) Mild to moderate CK/AST increase Toxemia and inflammation Anaerobic culture Cytology |
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What organisms cause clostridial myositis? What is the prognosis for each?
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C. perfringens (better prognosis but higher degree of IMHA)
C. septicum (worse prognosis) |
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How can the urine fractional excretion be determined?
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Measure serum and urine creatinine along with electrolyte concentration in serum and urine. Normalize ratio using creatinine.
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Which drugs are currently used to treat clostridial myositis in horses?
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Metronidazole
Oxytetracycline Choramphenicol |
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How can clostridial IMHA be determined?
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See autoagglutination in the blood after venipuncture
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What are some non-pharmaceutical management techniques for clostridial myositis?
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Debride and flush
IV fluids hydrotherapy topical wound therapy fly control |
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What go-home antibiotics should be given to a horse with clostridial myositis?
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Metronidazole or doxycycline
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What is the prognosis for clostridial myositis?
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68% mortality!
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What is the common signalment for a ruminant with clostridial myositis?
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Dead feedlot cow.
If they're alive, then fever, tachypnea, anorexia, depression with swelling and pain at affected site |
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How can clostridial myositis be prevented in ruminants? In horses?
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Ruminants (vaccinate)
Horses (no vaccine; avoid inappropriate IM injections) |
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What are two causes of viral myositis in horses?
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EHV1 and Equine Influenze A2
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How is sarcocystis myositis treated in ruminants? Horses?
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Ruminants (amprolium or ionophore abx)
Horses (anti-inflammatories, TMS + pyramethamine or ponazuril, steroids??) |
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What are the three forms of myopathies associated with respiratory pathogens? Which is most common?
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Immune-mediated polymyositis (most common)
Acute S. equi-associated rhabdomyolysis Infarctive hemorrhagic purpura |
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Which respiratory pathogens can cause myopathies? What is the most common one?
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S. equi most common
Also S. zooepidemicus, R. equi, C. pseudoTB) |
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Which of the following are associated with respiratory-associated myopathies?
a) atrophy b) significantly elevated CK c) mildly elevated CK/AST d) asymptomatic presentation |
a) atrophy
b) significantly elevated CK |
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What horse breed is typically impacted by immune-mediated polymyositis?
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young quarterhorse
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What is a typical finding upon physical exam of an animal with immune mediated polymyositis?
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severe and rapidly progressive muscle atrophy of the gluteal and epaxial muscles
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What will be seen on a biopsy of a horse with immune-mediated polymyositis?
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Lymphocytic inflammation
Anguloid atrophy Fiber necrosis and regeneration |
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How is immune-mediated polymyositis treated?
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Immunosuppress (dexamethasone and prednisolone)
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What proportion of immune-mediated polymyositis cases have a respiratory infection?
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only ~30%
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What laboratory anomalies are seen with S. equi rhabdomyolysis?
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(CBC) mature neutrophilia, hyperfibrinogenemia
(Chem) marked elevations in CK; LOW serum protein M |
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If you see a horse with lymphadenopathy and/or gutteral pouch empyema with stiffness and muscle pain, what should you be thinking? What is the prognosis?
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Strangles and S. equi rhabdomyolysis; very poor prognosis
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If a horse develops stiffness and colic within 3 weeks of vaccination against S. equi, what should you be thinking? What is the prognosis?
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Infarctive purpura; very poor prognosis
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What lab abnormalities will be seen with infarctive purpura?
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Left shift neutrophilia & toxic change
Hypoalbuminemia Marked high CK and AST HIGH serum M protein |
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What are two main differences in labwork that differentiate infarctive purpura from S. equi rhabdomyolysis?
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HIGH Serum M, Left shift neutrophilia in Purpura;
LOW serum M, mature neutrophilia in rhabdomyolysis |
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Traumatic myopathies are frequently related to what event?
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Anesthesia
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What are common sites for traumatic myopathies?
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Gluteals
Triceps Adductor muscles (draft horses) |
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How can traumatic myopathies be treated?
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Dantrolene (maybe pre-med)
Anti-inflammatories and analgesics IV fluids keep patient standing! |
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What are some differentials for heat stress myopathy in the down camelid?
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Meningeal worm
Trauma Systemic illness |
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What conditions are associated with Atypical Myopathy?
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Spring
Sudden, inclement weather Animals at pasture >12h/day |
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What are the major syndromes in nutritional myopathies? Which nutrients are they linked to?
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Skeletal muscle necrosis
Myocardial and diaphragmatic involvement Masseter muscle inflammation; (both due to VitE and/or Se deficiencies) |
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Which nutritional myopathy has a slower onset?
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Skeletal muscle necrosis
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Which nutritional myopathy involves sudden death?
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Myocardial and diaphragmatic involvement
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Describe the pathophysiology of nutritional myopathies?
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Oxidative damage; (Vit E is a free-radical scavenger; Se is necessary in glutathione peroxidase)
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If you see a seizing foal with high CK, muscle weakness, and persistent leukopenia, what might you think about?
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Glycogen Branching Enzyme Deficiency
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What are the two manners in which muscle can atrophy?
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Myogenic
Neurogenic |
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T or F:
Myogenic atrophy affects both type 1 and 2 fibers while neurogenic only affects type 1. |
False!
Neurogenic affects both Myogenic only affects type 2 |
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Neurogenic atrophy due to prolonged vitamin E deficiency is called...
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Equine Lower Motor Neuron Dz
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What are some causes of muscle fasciculations?
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Physiological response
Viral encephalitis Hypocalcemia Ear ticks HYPP Myotonia |
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Which tick can cause fasciculations? What is the pathogenesis?
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Otobius (ear tick); toxin alters Ach release from presynaptic terminals
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Delayed muscle relaxation is known as...
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...myotonia
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Describe the pathogenesis of myotonia.
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Abnormal membrane excitability due to reduced permeability to Cl.
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Percussion dimpling is a sign of...
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...myotonia
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What is a pathognomic test for myotonia?
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EMG ("dive bomber pattern")
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Biopsy of an animal with myotonia will show...
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...fiber size variation; hypertrophy of type 1 fibers
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Which channel is impacted in HYPP?
a) Ca channel b) K channel c) Na channel d) Cl channel |
c) Na channel
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What are signs of HYPP?
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Episodic weakness
Protrusion of 3rd eyelid Facal myotonia Sweating and fasciculations Dog-sitting |
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Which of the following are congruent with HYPP?
a) High CK/AST b) Normal biopsy c) Abnormal EMG d) Hyperkalemia |
b) Normal biopsy
c) Abnormal EMG Note - CK/AST is NORMAL; hyperkalemia is VARIABLE |
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How can HYPP be treated acutely? How can it be managed?
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Acute (IM adrenaline; feed grain or corn syrup; maybe Ca gluconate, dextrose, and/or NaHCO3)
Manage with low K in ration |
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Hypocalcemia in horses is assocated with...
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...lactation and transport
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Hypocalcemia must be differentiated from what infectious disease?
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Infectious tetanus!
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