Musculoskeletal 5 Flashcards
What are the four ways muscle injury can result?
Due to:
- Denervation - loss of connection with peripheral nerve - loss ofboth Type I/II
- Disuse - lack of muscle activity - typically loose type II
- Malnutrition/Cachexia/Starvation - protein catabolism + loss of fibres
- Endocrine disturbance - loss/excessive influence from hormonal activity
What is required for regeneration to be able to occur?
- Regeneration requires presence of basal lamina + satellite cells - myocytes themselves cannot regeneration
What does fibrosis in the muscle occur?
Occurs when basal lamina has been destroyed. It can follow an non-fatal injury + may be associated with atrophy
When does mineralisation occur?
Associated with:
- Necrosis
- Primary myopathies
- Vitamin D toxicity
Name the two different myopathies below and describe the difference between them:
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Polyphasic - a combination of multiple different myopathies - indicative of ongogin injury
Monophasic myopathy - only one stage so more likely to be indicative of a single insult
What are the four main clinical signs that are observed due to muscle disease?
- Lameness
- Recumbancy
- Excercise intolerance
- Renal signs - myoglobinuria (acute Rhabdomyolysis - can present just with renal signs)
What is the name of the condition that is shown below?
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Exertional Rhabdomyolysis - myofiber damage caused by primary excercise stress
What are the symptoms of capture rhabdomyolysis and what is the cause?
Clinical signs: Animals exhibit dyspnea, weakness, muscle tremors, muscle rigidity, hyperthermia
Cause: Increased circulating catecholamines due to stress
What is the suspected cause of canine exertional rhabdomyolysis?
Possibly associated with underlying dietary deficiencies - Vit E/Sel, Ca:P imbalance
What would be the effect of a defect in the production of myostatin?
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Excessive uncontrolled muscle proliferation
What would be the effect of a defect in the production of dystrophin?
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Lack of dystrophin would cause decreased building of muscle mass
What is the pathogenesis of malignant hyperthermia and what other clinical signs may be seen (other than that shown below)?
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- Defect in Ca++ channel (ryanodine receptor - RYR 1) - caused by stress, halothane, depoalarising muscle relaxant
- Ca++ channels remain open - prolonged myofiber contraction + muscle rigidity
- Hyperthermia + acute myonecrosis result in acute myonecrosis
Maliganant hyperthermia:
- Tachycardia
- Dyspnea
- Metabolic acidosis
What is the effect of hypothyroidism?
- Myofiber atrophy - associated with alterations in carbohydrate metabolism + energy loss from glycolysis + glycogenolysis - peripheral neuropathy w/axonal degeneration leading to denervation atrophy of type 1 and 2 fibres
How does hyperthyroidisim lead to muscle atrophy?
Increased catabolic state leads to negative energy balance
How does hyperadrenocorticism result in myofiber atrophy?
Increased catabolism + inherited synthesis of muscle proteins
Name the neoplasm that is shown below:
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Infiltrative lipoma
Name the condition that is shown below:
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Vitamin E/Senium deficiency:
- Deficiency in Vitamin E and/or selenium caused peroxidation of lipid membranes
- Ca2+ enters cytoplasm + mitochondria, damaging respiratory mechanisms and causing cell death
- Symmetrical necrosis of most active skeletal muscle (like postural muscles)
Name the two conditions that could be implicated below and suggest a test to differentiate them :
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Canine masticatory myositis: antibodies against myofibres in temporal + masseter muscles - 2M antibody blood test
Polymyositis: Most common in dogs, German shepards are overrepresented, No type 2M antibodies
Breifly explain the pathogenesis of myasthenia gravis and how the condition can be diagnosed:
- Production of antibodies against acetylcholine receptor
- Acquired form: diagnosed by detection of circulating anti-acetylcholine receptors antibodies
Name the condition that is shown below and complete the table with the common pathogens:
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Name the condition that is shown below and name the bacteria that is implicated in it:
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Clostridium chauvoei - balck leg
Name the condition that is shown below and suggest a potential cause:
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Myofiber necrosis by occluding intermuscular arteries - occlusion of large arteries via thrombi or compression (pressure)