Muscular disorders

Question 1

Rhabdomyolysis

- what

Answer 1

• break down of striated muscle

Question 2

Non-exertional rhabdomyolysis

- cause

Answer 2

• Clostridium spp., S. equi, viral infection, sarcocystosis, nutritional, toxin, trauma, post-anesthesia

Question 3

Clostridial myonecrosis

• species
• signs
• pathogenesis
• tx

Answer 3

• C. perfringens*, chauvoei, speticum, sordelli, novyi
• acute, severely ill, high mort.
• issue from toxins
• IV fluids, drain/open wound (as Clost. is anaerobic)

Question 4

How does Streptococcus equi cause myopathy

Answer 4

• immune mediated (type 3) myopathy
• M protein
• pupura hemorrhagica

Question 5

Viral associated-myopathy

• viruses
• pathogenesis

Answer 5

• Eq influenza, Eq herpes virus 1

- virus replicates in m. cells –> pyrogen release –> muscles aches, also virus kills m. cells

Question 6

Myopathy from sarcocystosis

• specie
• hosts
• patho

Answer 6

• S. fayeri, equicanis
• eq are intermediate hosts
• forms cysts in m.
• signs only when severe infection

Question 7

Post-anesth myoneuropathy

• common m.
• pathogenesis

Answer 7

• tricep, deltoid, masseter, gluteal, HL extensors
• can be generalized
• ischemia

Question 8

Nutritional myodegeneration

• pathogenesis
• cause

Answer 8

• prod of free radicals –> lack of scavengers –> m. degredation
• vit E and/or Se def

Question 9

Toxins damaging m.

Answer 9

• ionophores (monensin)
• tremetone (white snake root, rayless goldenrod)
• insecticide
• organophosphate

Question 10

Immune-mediated myositis dx

Answer 10

• incr CK and AST
• lymphocytic infiltrates on histo
• genetic test (MYH1)

Question 11

Pasture myopathy

• what
• signs
• plant and toxin
• predisposing factors
• BW
• tx
• prognosis

Answer 11

• acute rhabdomyolysis of grazing horses
• generalized degeneration of m. fibres
• sudden death (cardio-resp collapse), weakness, stiff, trembling, resp distress, low temp, myoglubinuria, conj hyperemia, subclin
• maple –> hypoglycin A
• fall and spring, Se/vitE def, stress, met imbalance
• in CK and AST, incr troponin I, hypoCa, hyperglycemia, azotemia, myoglobin
• IV fluids, NSAID, antioxidants (vt E, Se, C, DMSO), car supp, warming
• poor

Question 12

3 types of exertional myopathy

Answer 12

• local m. strain
• sporadic
• chronic

Question 13

Local exertional myopathy

• common m.
• causes

Answer 13

• lumbar, gluteal, adductor (Gracillis), semitendinosus

- tight turns and jumps, caught, IM inj, congenital

Question 14

sequalae of chronic local muscle strain

Answer 14

fibrotic myopathy

Question 15

Sporadic ER (exertional rhabdomyopathy)

• cause
• patho

Answer 15

• high intensity exercise, endurance, viral infections, electrolyte imbalance, vit E/Se def, high carbs
• tears intracelular myofilaments

Question 16

Chronic ER

• cause
• 2 disorders

Answer 16

• inherited

- glycogen storage disease, recurrent ER

Question 17

Glycogen storage disease

• breeds
• cause
• patho

Answer 17

• mutation in glycogen sythase 1

- incr storage and decr metabolism of glycogen

Question 18

Recurrent ER

• breed
• sign
• predisposing factors

Answer 18

• TB, ST, arabians
• epi of stiffness, sweating, m. contractions
• mare, nervous, sweet feed, exercise, excitement, lameness

Question 19

myofibrillar myopathy

• what
• signs
• histo

Answer 19

• intermitten ER, improper arrangement of myofibrils
• exercise intolerance
• cytoplasmic aggregates in m. fiber

Question 20

A way to test for exercise induced myopathy

Answer 20

• measure CK –> slow trot –> measure CK 4-6h post exercise

- will have >5x incr

Question 21

Tx for acute ER

Answer 21

• support
• fluids
• analgesia
• m. relaxants

Question 22

Tx for chronic ER

Answer 22

• vit E/Se
• fluids
• incr fat and decr starch in diet
• /- bicarb, thamine, methylsuldonylmethane