Muscle PP 2 Flashcards
Segmental Regeneration
Degenerate segments removed by MOs
Replaced by satellite cells
Fibrosis
Occurs secondary to significant inflammation, necrosis and hemorrhage
Osseous metaplasia
Secondary to hemorrhage
Woven bone production
What does vitamin E/ Selenium deficiency cause in pigs
Mulberry heart disease
fast-growing, healthy-looking pigs, affected pigs in nursery phase
Eosinophilic myositis (K9)
Muscles of mastication
May progress to atrophic myositis
Autoimmune disease targeting type 2 myocytes
Neosporosis (K9)
Neospora caninum
Ingesting infected tissue (aborted calves)
Necropurulent myositis
Myasthenia gravis (K9)
Generalized muscle weakness
↓ # of ACh receptors at myoneural junction
Maybe megaesophagus
Equine polysaccharide storage myopathy (EPSM)
Common genetic defect
Accumulation of polysacc aggregates in type 2 myocytes
Repeated bouts of myodegeneration → m. atrophy
Exertional Rhabdomyolysis other names
Azoturia
Monday morning disease
Setfast
Blackwater
Exertional Myopathy
CS of Exertional Rhabdomyolysis
Sudden stiff gate, reluctant to move, muscle swelling (gluteal), sweating
↑ CK and AST
Factors of Exertional Rhabdomyolysis
Signs during or immediately after exercise
High grain feeding and lack of regular exercise
Exertional Rhabdomyolysis pathogenesis
Muscle degeneration → myoglobinemia → nephrosis → myoglobinuria → renal failure → acidosis → shock → death
Forms of Exertional Rhabdomyolysis
“Typing up” - less severe form
Paralytic myoglobinuria/ monday morning disease- more severe form
Lesions of Exertional Rhabdomyolysis
Muscles are pale pink or diffusely red-tinged
Hyaline degeneration and necrosis
Hyperkalemic Periodic Paralysis (HYPP) in horses
Genetic disease (one copy of gene)
Muscle twitching and shaking episodes
Quarterhorses
Signs of HYPP
Muscle twitching
Shaking
Trembling
Weakness
Collapse
HYPP severe signs
@ 2-3 years of age
Difficulty swallowing, loud breathing noises
Sudden death (sometimes) after episode
Cause of HYPP
Mutation in muscles sodium channel
Stress or fasting followed by eating ↑ K (alfalfa)
Nutritional Myopathy
Vit. E/ Se deficiency in foals
Swollen, pale muscles with polyphasic myodegeneration
Seasonal Pasture Myopathy
Poisoning with Boxelder seeds (hypoglycin A)
Acute myodegeneration and necrosis
Lower Motor neuron disease
LMN loss → denervation atrophy of muscles
Clostridial myositis (porcine)
Wound infection with Clostridia sp.
Serohemorrhagic exudate, necrosis, muscle emphysema
Black leg (clostridial myositis)- ruminants
Cl. chavoei
Rancid butter smell (butyric acid)
Bruising → tissue destruction (bacterial toxins)
Malignant Edema
Severe edema
Gas bubbles (crepitus)
Discoloration of overlying skin
Coldness of affected area
Circulatory collapse and death
Clostridium Tetanus
Wound contamination
Tetanospasmin (exotoxin) → block inhibitory NT in UMN → spastic paralysis
Clostridium Botulism
Ingestion of spores in GI tract, contaminated wound
Neurotoxin → blocks ACh release in NMJ
Myotonia congenita(goats)
Thomsen’s disease= fainting goats
Inherited autosomal dominant trait
Affects chloride channels
Arthrogyposis
Innervation defect
In utero infection/ toxin ingestion → nervous system lesions → failure of innervation of skeletal m.
What toxins/ infections cause arthrogyposis
Akabane virus, bluetongue virus, poison hemlock, lupine plants
Cysticerosis
Taenia solium (pork tapeworm)
T. saginata (cow tapeworm)
Zoonotic!
Sarcocystosis
Affects mammals, birds, reptiles and herbivores (immediate host)
Invade m. fibers (tongue, heart, esophagus)
Zoonotic
Gross findings of Sarcocystosis
Large # of bradyzoites → cyst grossly visible with nodules, dots or streaks
Lipoma
Benign tumor of adipocytes in dogs
Liposarcoma
Malignant lipoma
Infiltrate adjacent soft tissues and muscle
Rhabdomyoma/ Rhabdomyosarcoma
Tumors that differentiate to form skeletal muscle
Benign and malignant forms
Leiomyoma
Smooth muscle tumor
Urinary bladder and genetalia
Equine melanoma
Grey horses
Metastasize to muscle fascia and extend to muscle
Hemangiosarcoma
Malignant vascular neoplasm arising within muscle
Common in horses and dogs
