Muscle PP 2

Question 1

Segmental Regeneration

Answer 1

Degenerate segments removed by MOs
Replaced by satellite cells

Question 2

Fibrosis

Answer 2

Occurs secondary to significant inflammation, necrosis and hemorrhage

Question 3

Osseous metaplasia

Answer 3

Secondary to hemorrhage
Woven bone production

Question 4

What does vitamin E/ Selenium deficiency cause in pigs

Answer 4

Mulberry heart disease
fast-growing, healthy-looking pigs, affected pigs in nursery phase

Question 5

Eosinophilic myositis (K9)

Answer 5

Muscles of mastication
May progress to atrophic myositis
Autoimmune disease targeting type 2 myocytes

Question 6

Neosporosis (K9)

Answer 6

Neospora caninum
Ingesting infected tissue (aborted calves)
Necropurulent myositis

Question 7

Myasthenia gravis (K9)

Answer 7

Generalized muscle weakness
↓ # of ACh receptors at myoneural junction
Maybe megaesophagus

Question 8

Equine polysaccharide storage myopathy (EPSM)

Answer 8

Common genetic defect
Accumulation of polysacc aggregates in type 2 myocytes
Repeated bouts of myodegeneration → m. atrophy

Question 9

Exertional Rhabdomyolysis other names

Answer 9

Azoturia
Monday morning disease
Setfast
Blackwater
Exertional Myopathy

Question 10

CS of Exertional Rhabdomyolysis

Answer 10

Sudden stiff gate, reluctant to move, muscle swelling (gluteal), sweating
↑ CK and AST

Question 11

Factors of Exertional Rhabdomyolysis

Answer 11

Signs during or immediately after exercise
High grain feeding and lack of regular exercise

Question 12

Exertional Rhabdomyolysis pathogenesis

Answer 12

Muscle degeneration → myoglobinemia → nephrosis → myoglobinuria → renal failure → acidosis → shock → death

Question 13

Forms of Exertional Rhabdomyolysis

Answer 13

“Typing up” - less severe form
Paralytic myoglobinuria/ monday morning disease- more severe form

Question 14

Lesions of Exertional Rhabdomyolysis

Answer 14

Muscles are pale pink or diffusely red-tinged
Hyaline degeneration and necrosis

Question 15

Hyperkalemic Periodic Paralysis (HYPP) in horses

Answer 15

Genetic disease (one copy of gene)
Muscle twitching and shaking episodes
Quarterhorses

Question 16

Signs of HYPP

Answer 16

Muscle twitching
Shaking
Trembling
Weakness
Collapse

Question 17

HYPP severe signs

Answer 17

@ 2-3 years of age
Difficulty swallowing, loud breathing noises
Sudden death (sometimes) after episode

Question 18

Cause of HYPP

Answer 18

Mutation in muscles sodium channel
Stress or fasting followed by eating ↑ K (alfalfa)

Question 19

Nutritional Myopathy

Answer 19

Vit. E/ Se deficiency in foals
Swollen, pale muscles with polyphasic myodegeneration

Question 20

Seasonal Pasture Myopathy

Answer 20

Poisoning with Boxelder seeds (hypoglycin A)
Acute myodegeneration and necrosis

Question 21

Lower Motor neuron disease

Answer 21

LMN loss → denervation atrophy of muscles

Question 22

Clostridial myositis (porcine)

Answer 22

Wound infection with Clostridia sp.
Serohemorrhagic exudate, necrosis, muscle emphysema

Question 23

Black leg (clostridial myositis)- ruminants

Answer 23

Cl. chavoei
Rancid butter smell (butyric acid)
Bruising → tissue destruction (bacterial toxins)

Question 24

Malignant Edema

Answer 24

Severe edema
Gas bubbles (crepitus)
Discoloration of overlying skin
Coldness of affected area
Circulatory collapse and death

Question 25

Clostridium Tetanus

Answer 25

Wound contamination Tetanospasmin (exotoxin) → block inhibitory NT in UMN → spastic paralysis

Question 26

Clostridium Botulism

Answer 26

Ingestion of spores in GI tract, contaminated wound Neurotoxin → blocks ACh release in NMJ

Question 27

Myotonia congenita(goats)

Answer 27

Thomsen's disease= fainting goats Inherited autosomal dominant trait Affects chloride channels

Question 28

Arthrogyposis

Answer 28

Innervation defect In utero infection/ toxin ingestion → nervous system lesions → failure of innervation of skeletal m.

Question 29

What toxins/ infections cause arthrogyposis

Answer 29

Akabane virus, bluetongue virus, poison hemlock, lupine plants

Question 30

Cysticerosis

Answer 30

Taenia solium (pork tapeworm) T. saginata (cow tapeworm) Zoonotic!

Question 31

Sarcocystosis

Answer 31

Affects mammals, birds, reptiles and herbivores (immediate host) Invade m. fibers (tongue, heart, esophagus) Zoonotic

Question 32

Gross findings of Sarcocystosis

Answer 32

Large # of bradyzoites → cyst grossly visible with nodules, dots or streaks

Question 33

Lipoma

Answer 33

Benign tumor of adipocytes in dogs

Question 34

Liposarcoma

Answer 34

Malignant lipoma Infiltrate adjacent soft tissues and muscle

Question 35

Rhabdomyoma/ Rhabdomyosarcoma

Answer 35

Tumors that differentiate to form skeletal muscle Benign and malignant forms

Question 36

Leiomyoma

Answer 36

Smooth muscle tumor Urinary bladder and genetalia

Question 37

Equine melanoma

Answer 37

Grey horses Metastasize to muscle fascia and extend to muscle

Question 38

Hemangiosarcoma

Answer 38

Malignant vascular neoplasm arising within muscle Common in horses and dogs