Skeletal Muscle Flashcards
(45 cards)
Necropsy of a lamb, show s pale, swollen, and dry skeletal muscles. They have a history of weakness and stiff gait.
What pathological process could account for this appearance?
Degeneration/necrosis
Circulatory disorder
Necropsy of a lamb, show s pale, swollen, and dry skeletal muscles. They have a history of weakness and stiff gait.
What is your gross morphological diagnosis ?
Skeletal muscle degeneration and necrosis
Rhabdomyolysis
Myonecrosis
Zenker’s necrosis
What is the histopathological appearance of muscles when they die?
Vacuolation of sarcoplasm
Condensation of sarcoplasm-> hyper-eosinophilic and lose striations
Nuclear pyknosis
Calcification (dystrophic)
What is the histopathological appearance of muscles when they regenerate?
Internalization of nuclei
Macrophage infiltrate
What are the causes of polyphasic lesions in muscle?
Nutritional deficiency -vitamin E/Se
Ongoing toxicities
Genetic defects in myoctye structural/metabolic elements
What is the pathogenesis of vitamin E/Se deficiency leading to muscular degeneration ?
Glutatione peroxidase/reductase requires vit E/Se for function -> lack of ability to scavenge free radicals -> oxidative damage (lipoperoxidation of cell membrane)-> myocyte injury
Sudden onset of a wobbly gait, colic, and decreased exercise tolerance, recumbency, and death in horse. Histopathology shows monophasic skeletal muscle.
What is the most likely cause?
Monophasic lesions -single insult
Trauma (focal)
Exertion/capture
Toxin
This case is toxin- ionoophores
What is an ionophore coccidiostat that results in a Ca overload of myocytes in horses?
Monensin
What causes white muscle disease? Where do you see these lesions
Vitamin E/Se deficiency
Lesions in most active muscles (eg heart)
_______________ is when ionic events of contraction produce an adverse environment
Exertional rhabdomyolysis
Under extreme stress or have underlying metabolic conditions
__________ is excess nitrogen in the urine
Azoturia
What is capture myopathy?
Exertion, stress during capture
Anaerobic glycolysis -> hyperthermia and metabolic acidosis
What leads to abnormal kidney in capture myopathy
Damage muscle -> free myoglobin filtered in glomerulus -> renal failure
What is the pathogenesis of porcine stress syndrome?
Inherited defect in skeletal muscle ryanodine receptor -> excessive Ca release and contraction when stimulated -> heat production and myocyte necrosis
Muscles are dark red, swollen, softened/friable, and have palpable crepitus.
What pathological process could account for this appearance?
Circulatory disorder
Muscles are dark red, swollen, softened/friable, and have palpable crepitus.
Histopathology shows acute necrotic and hemorrhagic myositis and a gram positive bacilli?
What is your Dx?
Black leg - clostridium chauvoei
What is the pathogenesis of black leg?
Ingest spore-> muscle via blood -> tissue hypoxia/acidosis (anaerobic bacteria) -> bacterial proliferation -> production of exotoxins -> myonecrosis and systemic endothelial damage -> death from septicemic shock/bacterial toxemia
What are outbreaks of clostridium chauvoei associated with?
Parturition
Holding- IM meds, marking, shearing
Trauma during confinement
Soil disturbance
What are the causes of inciting myositis?
Necrotic/hemorrhage - C. Chauvoei / C. Septicemia
Superlative - pyogenic bacteria
Lymphocytic - immune mediated
Eosinophilic -Protozoa/parasite/immune mediated
Granulomatous
What intralesional protozoa are present in the muscle of small animals?
Toxoplasma
Neospora
Sarcocystis spp infection will cause __________ myositis in cows or horse
Eosinophilic (protozoa)
What is your MDx for muscle that has discrete areas of muscle pallor bordered by reddened zones ?
Muscle infarct
What is the pathogenesis of muscle infarct due to increased pressure?
Increase pressure -> poor perfusion -> ischemia -> infarct
What is compartment syndrome?
Rapid muscle growth -> period of increased circulation (exertional) -> muscle swelling confined by facia -> impeded blood supply -> ischemia -> infarct
