LEC 5, 6 - Skeletal Muscle I/II Flashcards Preview

Pathology II > LEC 5, 6 - Skeletal Muscle I/II > Flashcards

Flashcards in LEC 5, 6 - Skeletal Muscle I/II Deck (234):
1

What are muscles made of? Describe.

Myofibers 

Long, multinucleated cells 

Little to no regenerative capacity

2

Describe: Type 1 muscle

Rich in mitochondria 

High oxidative metabolism 

Slow contracting/fatiguing 

 

3

Describe: Type 2A 

Mixed oxidative/glycolytic metabolism 

Fast contracting 

Slow fatiguing 

Quick, short contractions

4

Describe: Type 2B 

Glycolytic metabolism 

Fast contracting/Fatiguing 

5

Describe: Type 2c 

Regernating fibers

6

Describe: Stellate cells

Run along length of myofibers 

Full capacity of division + fusion

Restore - mature myofibers 

7

What are the two classifications of changes in myofibers?

Neuropathic 

Myopathic 

8

What are neuropathic changes to myofibers?

Effect or absence of nerve supply

9

What are myopathic changes in myofibers?

Primary changes within muscle cells/fibers

10

What is involved in nueromusclar disease?

Lower motor neurons 

Peripheral nerves 

Neuromusclar junctions and muscles 

11

What are clinicopathologic findings to suggest that there is damage to the muscle?

Creatine kinase elevation 

AST + LDH elevation 

Carbonic anhydrase III + FABP 

12

Possible cause for pallor

Necrosis 

Denervation 

Anemia 

Young animals

13

Possible cause for pale streaking

Necrosis 

Mineralization

14

Possible cause for dark red mottling

Congestion 

Hemorrhagic necrosis 

Inflammation 

Myoglobin staining 

Hypostatic congstion

15

Possible cause for green color to muscles

Eosinophilic inflammation 

Putrefaction 

16

Possible cause for lipofuscin 

Old animals 

Especially cattle

17

Possible cause for black

melanosis 

melanoma 

18

Possible cause for thickened/firm muscle texture

Mineralization 

Calcification 

Fibrosis 

19

Possible cause for soft texture to muscles 

Fat infiltration or necrosis 

Autolysis

20

How do you collect muscle samples?

Collect strip not larger than 1 cm 

Myofibers running length wise 

Place sample on rigid surface to avoid contraction band artifact 

21

What are degenerative muscle disease?

Myopathies resulting in segmental or global necrosis in which inflammatory cells are not the cause of damage

22

What are the possible causes of degenerative muscle disease?

Ischemia 

Nutritional deficiencies 

Toxic myopathies

Extertional myopathies 

23

What can cause ischemia that leads to degerneation of the muscle?

Occulusion of a major blood vessel 

External pressure on a muscle 

Swelling of a muscle in a nonexpendable compartment 

Vasculitis

24

What is an example of ischemic necrosis in cattle?

Downer cow syndrome 

25

What animal most commonly sees muscle degeneration due to nutritional defiecencies?

Livestock

26

What nutritional deficiencies cause muscle degeneration?

Vitamin E 

Selenium 

 

27

What is the function of selenium?

trace mineral vital of glutathione peroxidase system 

Protects from oxidative injurt

28

What disease does selenium deficiency cause?

White muscle disease

29

What are the three major toxins that cause muscle degeneration?

Ionophores 

Plants 

Pasture-associated myopathy

30

Who is affected by pasture-associated myopathy?

Horses

31

What are the ionophores that can cause muscle degeneration?

Monensin 

Narasin 

etc. 

32

What are examples of plants that cause muscle degeneration?

Cassia occidentalis 

Gossypol 

33

What predisposes an animal to exertional myopathies?

Vit E/Selenium deficency 

Muscular dystrophy

Glycogen storage disease 

Severe electrolyte depletion 

34

What are examples of extertional rhabdomyolysis?

Black-water 

Monday morning sickness

35

What are the three classes of congenital defects that lead to musclar degeneration?

Anatomic defects 

Muscular dystrophy 

Myotonia 

36

Describe: Muscular dystrophy

Inherited, progressive, degenerative primary disease of myofibers 

Ongoing necrosis + regeneration 

37

What is a disease of muscular dystrophy in cats and dogs? What is affected?

Duchennes's muscular dystrophy 

Dystrophin gene 

38

Describe: Myotonia 

aka Channelopathies

Inability of myofibers to relax 

= spasmodic contractions 

Most due to abnormal ion channel formation

39

What are the three types of anatomical defects that lead to musclar degeneration?

Innervation 

Genetic 

Failure of normal development 

40

What is an example of genetic defect in cattle and dogs that cuase muscular degeneration?

Double muscling 

aka congenital muscular hyperplasia 

41

How does malignant hyperthermia occur?

Unregulated release of calcium from sarcoplasmic reticulum 

Leads to excessive contraction = heat

Increased body temperature is the result

42

What animals are affected by malignant hyperthermia?

Dogs + Horses + Pigs

43

What is the defect in exactly that causes malignant hyperthermia?

Ryanodine receptor

44

What can trigger a maligant hyperthermia episode?

General anesthetic 

Stress - porcine stress syndrome

45

What characterizes a metabolic myopathy?

Reduced muscle cell energy production

46

Describe: Type II Glycogenoses

Acid maltase deficiency

47

Describe: Type IV glycogenoses

Glycogen branching enzyme deficiency

 

48

Describe: Type V glycogenoses

Myophosphorylase deficency 

49

Describe: Type VII glycogenoses

Phosphofructokinase deficiency 

50

What occurs with most endocrine myopathies?

Result in muscle atrophy 

Mostly in type 2 fibers 

51

What happens in dogs with hypercortisolism?

Hypertrophy 

Pseudomyotonia 

52

What electrolyte imbalances can cause muscle weakness?

Hypocalcemia 

Hypokalemia 

Hypophosphatemia 

Hypernatremia 

53

Describe: Neuromuscular junction disorders

Impair the ability nerves impulses across the neuromuscular juncton 

54

What are the three most common neuromuscular junction disorders?

Myastenia gravis

Botulism 

Tick paralysis

55

What is the tick responsible for tick paralysis? 

Dermacentor 

Ixodes 

56

How does tick paralysis occur?

Toxin from tick block the release of acetylcholine from axon terminal 

57

What animal is most commonly infected by tick paralysis?

Dogs

58

how is recovery initiated in regards to tick paralysis?

Removal of the tick 

Rapid 

24 to 48 hours

59

What bacteria is responsible for botulism?

Clostridium botulism 

60

Where is clostridium found?

GI tract 

soil

61

What is botulism characterized by?

Profound flaccid paralysis 

 

62

What is the mechanism by which the botulism toxin causes paralysis?

Cleavage of proteins in charge of release of acetylcholine from presynaptic vesciles 

63

What type of botulism toxin are dogs most sensitive to?

type C

64

What type of botulism toxin are cattle most sensitive to?

Type C + D 

65

What type of botulism toxins are horses most sensitive to?

Type B + C 

66

What animal is most sensitive to botulism overall?

Horses

67

How does the acquired form of myasthenia gravis occur?

Immune-mediated disorder caused via circulated autoantibodies against skeletal muscle acetylcholine receptor

68

What is the acquired form of myasthenia gravis associated with?

Thymic abnormalities 

Secondary loss of self-tolerance to acetylcholine receptors

69

How is the acquired form of myasthenia gravis diagnosed?

Detection of autoantibodies to acetylcholine receptors in the blood

70

How does the congenital form of myasthenia gravis occur?

Dogs and Cats

Born with defective NMJ that decrease membrane surface area as a result of reduced actylcholine receptor density 

71

What are the signs of myasthenia gravis?

Profound, sustained and progressive muscle weakness

72

What are the primary neoplasms of the muscle?

Rhabdomyoma/Rhabdomyosarcoma 

Peripheral nerve sheath tumors 

Fibromas/sarcomas 

Hemangiomas/sarcomas 

73

What does rhabdomyoma/sarcoma arise from?

Intramuscular pluripotential cells 

Dogs + horses + Cats

74

Describe: Rhabdomyoma

Benign 

Smooth, nodular, pink, unencapsulated 

 

75

Where are rhabdomyomas most commonly occur?

Larynx of adult dogs 

76

Where are rhabdomyosarcomas most commonly found?

Neck 

Oral Cavity - Tongue

77

What do rhabdomyosarcomas look like grossly?

Grossly pink and fleshy, often have prominent local invasion 

Malignant 

78

Where do hemangiosarcomas most commonly metastasize to?

Lungs

79

What animals are hemangiosarcomas most commonly found in?

Horses 

Dog

80

What is seen with clostridial myositis in horses?

Malignant edema 

Gas gangrene 

81

What are the clostridium species that infect horses causing clostridial myositis?

Septicum 

Perfringens

Chauvoei

Novyi 

Fallax

82

How does clostridium infect the muscles of a horse?

Penetrating wounds 

Blood stream 

 

83

What does clostridium do in anaerobic condition?

Bacteria proliferate 

Produce toxins 

Result in: 

Hemorrhage 

Edema 

Necrosis 

84

What are the clinical signs of clostridial myositis?

Acute onset of heat, swelling and pain 

Fever, depression, anorexia, and dehydration 

Mild to Moderate increase in CK + AST

85

What does the muscle look like grossly when infected with clostridial myositis?

Swollen, edematous, and hemorrhagic 

Dark red to pale areas 

Suppurative exudate 

Gas bubbles 

86

What are the clinical signs of botulism?

Flaccid paralysis 

Dysphagia

Tongue + Eyelid weakness 

CK and AST are WNL 

87

What is seen either grossly or histologically with botulism?

No findings 

Aspiration pneumonia can occur 

88

What is used to diagnose animal with botulism?

Detection of toxin in stomach contents 

89

What bateria is responsible for piegon fever?

Corynebacterium pseudotuberculosis

90

What are the clinical signs of piegon fever?

Multifocal intramusclar abscesses 

Pectoral muscle most commonly infected 

Common fever

91

What is seen grossly with pigeon fever?

Swelling + Edema 

Localized areas of suppurative exudate accumulation

92

What is the pathogenesis of pigeon fever?

Enter the body through wounds 

Bacterial exotoxin (phospholipase D) 

Leads to vascular damage + Inhibits neutrophil function

93

What are the two degenerative myopathies associated with streptococcus equi equi infections?

Purpura hemorrhagica 

Rhabdomyloysis + muscle atrophy 

94

What is seen histologically with purpura hemorrhagica?

Leukocytoclastic vasculitis 

Fibrinoid necrosis of blood vessels 

95

What is the gross appearance of purpura hemorrhagica?

Multiple muscles 

Disscecting hemorrhage + edema 

No gas bubbles 

96

What are the clinical signs of purpura hemorrhagica?

Depression 

Fever 

Petechial +/- ecchymoses 

Anemia 

Myoglobinuria 

Very High CK + AST 

97

What is the pathogenesis of purpura hemorrhagica? 

Immune response to bacteria 

Immune complexes form (IgA + Antigen) 

Deposit in small blood vessels 

Vasculitis --> vascular necrosis > hemorrhage > ischemia 

98

What is the gross appearance of streptococcal-associated rhabdomyosis?

Decrease in muscle mass

99

What are the clinical signs of streptococcal-associated rhabdomyolysis + muscle atrophy?

Atrophy along paraspinal + gluteal muscles 

High elevations of CK + AST 

No purpura hemorrhagica seen 

100

What is the pathogenesis of streptococcal-associated rhabdomyolysis?

Predisposed to immune-mediated damage caused by cross-reaction of streptococcal antibodies with muscle proteins

101

What animals are most likely to get streptococcal-associated rhabdomyolysis?

Young animals 

Quarter horses 

102

What is the cause of protozoal myopathy?

Sarcocystis 

Most commonly Fayeri

103

What is seen histologically with protozoal myopahty?

Cysts within myofibers 

No inflammatory reaction generated 

104

What is the pathogenesis of nutritional myopathy?

Lack of elements enhance oxidative injury of actively contracting muscle fibers 

105

What is the gross appearance of nutritional myopathy?

Depends on stage of necrosis 

 

106

What are the clinical signs of nutritional myopathy?

Weak suckling or impaired mastication

Chronic = 

Bilateral symmetrical atrophy of masseter musccles 

Mild to moderate increase in CK + AST

107

What is the pathogenesis behind ionophore toxicity?

Results in calicum overload 

Leads to necrosis of skeletal + cardiac muscle cells 

 

108

Describe: Hyperkalemic periodic paralysis

Myotonic disorder 

Autosomal dominant 

Point mutation in gene encoding for alpha unit of skeletal muscle sodium channel 

109

What are the gross findings in HYPP?

None

110

What is seen histologically in HYPP cases?

Vacular degeneration of type 2 myofibers 

111

What are the clinical signs of HYPP?

Transient muscle spasms

Protrustion of third eyelid 

Gerenalized flaccid paralysis 

CK + AST normal 

112

What is the pathogenesis of HYPP?

Delayed inactivation of sodium channel acitivity 

Leads to membrane instability + continous electrical activity 

113

Describe: Equine polysaccharide storage myopathy

Autosomal dominant trait 

Point mutation in skeletal muscle glycogen synthase 1 gene 

(GYS1) 

114

What horses are most affected by EPSSm?

Quarter horse 

Warm blood 

Arabian 

Morgan 

Pony of Americas

115

What are the clinical signs of EPSSM?

Stiff gait 

Symmetric muscle atrophy 

Back soreness 

Muscle cramping 

CK + AST normal

116

What is seen histologically with EPSSM?

Aggregates of intracytoplasmic material 

Stains postive with PAS reaction for glycogen 

117

What is seen grossly with EPSSM?

Affected muscles are pale pink or diffusely red tinged 

118

What is the pathogensis of EPSSM?

Accumulation of glycogen within myofibers 

Leads to insuffiecent energy prodcution + abnormal myofiber function

119

Describe: Glycogen brancher enzyme deficiency

Autosomal recessive 

Accumulation of unbranched chains of glycose occur wtihin the cell 

Leads to abnormal glycogen formation + intramyofiber deposits 

120

What are the gross findings with GBE def?

None

121

What are the clinical signs of GBE def?

Foals may be aborted, stillborn, or weak 

Contracted tendons 

Rhabdomyosis or cardiac failure early in life

122

What is seen histologically with GBE def?

Hyaline inclusions within skeletal and cardiac muscle 

RESISTANT TO AMYLASE DIGESTION 

Positive stain with PAS

123

What is the cause of monday morning sicknees?

Unknown 

Associated with: 

Nutritional myopathy 

EPSSM 

Hypothyroidism

124

What is seen grossly with monday morning sickness?

Similar to EPSSM 

125

What is seen histologically with monday morning sickness?

Localized widespread type 2 myofiber necrosis 

Macrophage infiltration/regeneration

126

What are the clinical signs of monday morning sickness?

Sudden onset of stiff gait 

Reluctance to move 

Swelling of muscle grousp 

CK + AST markedly elevated 

127

What does ischemic myopathy affect?

Pectoral 

Abodominal 

Limb muscles 

128

Describe: Postanesthetic myopathy

Occurs in horses 

Prolonged recumbency during general anesthesia

129

What are the four peripheral neuropathies in horses?

Sweeny 

Stringhalt 

Fibrotic myopathy 

Laryngeal hemiplagia

130

Describe: Sweeny

Unilateral scapular muscle atrophy 

Due to traunma or damage to suprascapular nerve 

Poorly fitted harness

131

Describe: Stringhalt

Sporadic pelvic limb neuropathy 

Exaggerated flexion of one or both limbs 

Unknown cause 

Possible: Hypochoeris plant 

132

Describe: Fibrotic myopathy

Hamstring muscle trauma 

restriction of forward swing of affected limb

133

What nerve is affected in laryngeal hemiplagia?

Left recurrent laryngeal 

134

What are possible causes of laryngeal hemiplagia?

Lead toxicity 

Direct trauma 

Extension of guttural pouch infection and/or tumors 

 

135

What is a characteristic of laryngeal hemiplagia?

roaring nose

136

What are the two kinds of motor neuronopathies seen in horses?

Equine protozoal myeloencephalitis 

Equine motor neuron disease

137

What organism is responsible for EPM?

Sarcocystic neurona 

138

How does EPM occur?

Denervation atrophy of fasical + gluteal muscles 

139

What causes equine motor neuron disease?

Prolonged vit E deficiency 

140

What are the clinical signs of equine motor neuron disease?

Rapid muscle wasting 

Weakness 

Trembling 

Recumbency 

141

What is seen grossly in a horse with equine motor neuron disesae?

Muscles turn yello-tan 

Gelatinous textures

142

What bacteria is responsible for black leg in cattle?

Clostridial myositis 

143

What is the pathogenesis of blackleg?

Spores remain dormate in muscle 

Trauma occurs 

Hypoxia/anoia leads to spore activation 

Bacterial production of toxins 

Capillary wall damage 

Hemorrhage + Edema + Necrosis

144

What are the pyogenic bacteria that affect cattle?

Trueperella pyogenes 

Actinobacillus lignieresii 

Actinomyces bovis 

145

What does actinomyces bovis cause in cattle?

Lumpy jaw 

146

What is the pathogenesis of lumpy jaw?

Bacteria infects bone of jaw 

Chronic granulomatous to pyogranulomatous/fibrosing osteomyelitis 

147

What does actinobacillus lignieresii cause in cattle?

Wooden tongue 

148

What are the clinical signs of wooden tongue in cattle?

Excessive salivation due to difficulty swallowing

149

What are the gross findings with wooden tongue?

Rigid and swollen tongue 

150

What is seen histologically with wooden tongue?

Mark fibrosis 

Multiple areas of pyo/granulomatous inflammation 

Contains eosinophilci material 

151

What is the pathogenesis of wooden tongue?

Severe granulomatous to pyogranulomatous 

Fibrosis myositisi glossitis 

 

152

What are the gross findings in cattle infected with trueperella pyogenes?

Single or multiple 

Abscesses and/or cellulitis 

Thick, yellow-green, foul smelling pus 

153

What are the protozoal myopathies in cattle?

Sarcosytis 

Eosinphilic myositisi

Neospora caninum 

154

What occurs with neospora caninum infections in cattle? 

No clinical disease in cattle 

Can infect fetus leading to abortion 

155

Describe: Eosinophilic myositis 

Sarcocystis infection 

Involved in hypersensitivity 

Green discoloration of muscle due to massive infiltration of EOS 

Necrosis and fibrosis occur 

156

What muscles are most affected by nutritional myopathy in cattle?

Postural + Locomotion 

157

How is nutritional myopathy diagnosed in cattle?

Blood levels of vit e. and selenium 

158

What plant most commonly causes degenerative myopathy in cattle?

Cassia occidentalis 

aka coffee weed 

159

What does coffee weed cause in cattle?

Necrosis 

Minimal to no mineralization

160

What are the clinical signs of ionophore toxicity?

Diarrhea 

Anorexia 

Generalized weakness

CK + AST exteremely high 

161

What is the cause of steatosis in cattle?

Defective in-utero muscle development 

Replacement of adiopocytes 

162

What is seen histologically in cattle with steatosis?

Replacement of myofibers by adiopocytes 

Sudan black stain 

163

Describe: Congenital muscular hyperplasia

Defect in myostatin gene

164

Animal affected: Multisystemic necrotizing vasculopathy

young Gelbvieh cattle 

165

Animal affected: Motor neuron degenerative disease 

Brown Swiss cattle 

166

What are the causes of hypokalemic myopathy in cattle?

Anorexia 

Ketosis 

Glucocorticoids iwth high mineralcorticoid activity 

Activation of glucose transport w/ IV administration

167

What are the clinical signs of hypokalemic myopath?

Weakness

Recumbency 

CK + AST moderatly elevated

168

What are the gross findings in hypokalemic myopathy?

None specific

Necrosis of strenal muscles 

 

169

What are the bacterial/protozoal myopathies in small ruminants and camelids?

Clostridial myositis

Botulism 

Protozoal myopathy

170

What plant causes toxic myopathy in goats?

Porsopis glandulosa - honey mesquite 

171

What does honey mesquite do to goats?

Degeneration of motor nucleus of the trigeminal nerve

Denervation of masticatory muscles 

Progressive emaciation due to inability to eat

172

What are the clinical signs of myotonia in goats?

Severe muscle spasms characterized by stiffness

Adoption of sawhorse stance 

CK + AST normal 

173

What is since histologically in goats with myotonia?

Moderate myofiber hypertrophy

174

What is the cause of myotonia in goats?

Genetic defect of skeletal muscle chloride channel 

Decreased chloride conductance 

Ionic instability of sarcolemma 

175

Describe: Megaesophagus in camelids

Tunica muscularis contains skeletal muscle 

Abnormal motility + dilation occur in adults 

Unknown cuase 

176

What are the causes of bacterial myopathies in pigs?

Clostridium septicum 

T. pyogenes 

Trichinosis 

177

What does T. pyogenes cause in pigs?

Pyogenic 

Muscular abscesses + cellulitis 

178

What is the cause of trichinosis in pigs?

Trichinella ssp.

179

What are the gross findings in pigs with a trichinosis infection?

Small white nodules in muscle

180

What is seen histologically in pigs with a trichinosis infection?

Mixed inflammatory infiltrate inducing EOS 

181

What is the pathogensis of trichinosis of pigs?

Adult nematode lives in SI 

Larvae penetrate mucosa + reach bloodstream 

Larvae encyst in myofibers 

Active muscle preferentially affected 

182

What is plant affects pigs? How?

Cassia occidentalis 

Diaphragm 

183

How does ionophore toxicity affect pigs?

Atria of the heart

184

What does gossypol cause in pigs?

Skeletal + Cardiac muscle necrosis 

Liver + Lungs lesions 

185

Describe: Myofibrillar hypoplasia 

aka Splay leg 

Abduction of limbs laterally 

Progressive flattension of the sternum 

Young piglets

186

What pigs are most commonly affected by Porcine stress syndrome?

Pigs with unpigmented hair coats

187

What is the cause of porcine stress syndrome?

Genetic defect in ryanodine receptor 

188

What are the clinical signs of porcine stress syndrome?

Dramatically increased body temperature 

Severe muscle rigidity 

CK + AST markedly elevated 

189

What gross findings are seen with porcine stress syndrome?

Muscles are pale, moist, swollen, and appear cooked

Shoulder, back, and thigh most affected

190

What is seen histologically with porcine stress syndrome?

Myofibers 

Hypercontracted 

or 

Coagulative necrosis 

191

What is the pathogenesis of porcine stress syndrome?

Ryanodine receptor = Calcium release channel in SR 

Uncontrolled intracytoplasimic Ca Release 

Excessive contraction 

Heat production

192

What causes protozoal myopathy in dogs?

Neospora caninum 

193

What are clinical signs of neospora infection in a dog?

Progressive weakness

Marked muscle atrophy 

CK + AST slightly increased

194

What is seen grossly in dogs infected with neospora?

Atrophied, pale and firm muscles

195

What is seen histologically in dogs with a neospora infection?

Myofiber necrosis 

Lymphoplasmacyctic inflammatory infiltrate 

Intracytoplasmic protozoal cysts

196

What is the pathogenesis of neospora infection in dogs?

Transmitted in utero 

Invade peripheral nervous system + skeletal muscle 

Affects ventral spinal roots = denervation of muscles 

197

What are the clinical signs of Duchenne's type?

progressive weakness

death 

Less severe: stiff short strife gait and excercise 

198

What is the cause of Duchenne's type in dogs?

Dystropin gene affected 

Codes for membrane associated cytoskeletal protein 

Repeated bouts of myofiber necrosis + regeneration 

199

What causes death in Duchenne's type?

Respiratory failure related to severe diaphragmatic necrosis 

200

What is seen histologically with Duchenne's type?

Necrosis 

Mineralization 

Progressive dissecting fibrosis 

201

What are the clinical signs of Lab. retriever centronuclear myopathy?

Neuromuscular weakness first 6 months 

Excercise intolerance 

Loss of patellar + triceps reflex 

CK + AST normal 

 

202

What are the gross findings seen with centronuclear myopathy?

Poor muscling 

Possible megaesophagus 

203

What is seen histologically with centronuclear myopathy?

Clusters of atrophic myofibers 

Myofiber hypertrophy 

Nuclei internalization 

204

What breeds of dogs are affected by congenital myotonia?

Chow chow 

Miniature schnauzer 

Staffordshire terrier

205

What are the gross and histological findings of congenital myotonia in dogs?

Marked musclar hypertrophy

206

What are the clincal signs of congenital myotonia in dogs?

Movement with splayed, stiff thoracic limbs 

Bunny hop gait in pelvic limbs 

 

207

What is the cause of congenital myotonia?

Decreased chloride conduction 

 

208

What are the endocrine myopathies seen in dogs?

Hypothyroidism 

Hypercortisolism 

209

What are the clinical signs of hypothyroidism?

Weakness

Muscle atrophy

Laryngeal paralysis 

Megaesophagus

210

What are the gross findings in a dog with hypothyroidism?

Overall muscle atrophy 

Thyroid gland bilateral atrophy 

Megaesophagus 

211

What is seen histologically in a dog with hypothyroid ism?

Atrophy of type 2 myofibers 

Axonal degeneration 

212

What causes hypercortisolism in dogs?

Increased adrenocortical cortisol production 

Exogenous corticosteroids 

213

What are the clinical signs of hypercortisolism in dogs?

neuromuscular weakness 

CK + AST normal 

Cushingoid pseudomyotonia 

214

Define: Cushingoid pseudomyotonia

Remarkabley stiff, stilted pelvic gait

Increased muscle tone of proximal thigh muscles

215

What are the gross + histological findings in a dog with hypercortisolism?

Sysmmetric muscle atrophy 

Alopecia 

Bilateral cortical atrophy 

 

216

What causes polymyositis in dogs?

Antibodies directed to skeletal muscles only 

217

What are the gross findings in dogs with polymysitis?

Muscle throughout body can be affected 

Atrophy of temporal + masseter muscles 

Esophageal muscle involvement = megaesophagus 

 

218

What is seen histologically in acute cases of polymuositisi?

Lymphocytic myosistisi 

Variable degree myofiber necrosis 

219

What is seen histologically in chronic cases of polymyositis?

Regeneration 

Fibrosis 

220

What causes masticatory myositis?

Antibodies against myosin isoform present in type 2 myofibers in dogs 

221

What are the clincal/gross findings in a dog with masticatory myositisis?

Bilateral symmetric swelling of temporalis and masseter muscles 

Inability of full opening of the jaw 

222

What is histological appearance of masticatory myosistis in dogs?

Lymphocytic myosistis (B-lymphocytes) 

Numerous eosinophils 

Necrosis 

Regeneration of myfibers 

223

What dogs seem to get extraocular muscle myositis?

< 2 years old 

Golden retrivers 

224

How does extraocular muscle myositis present?

Actue onset of bilateral exopthalmos 

225

What are the gross findings seen with extraocular muscle myosistis?

Extraocular muscles are swollen + pale yellow 

226

What is seen histologically with extraocular muscle myosistis?

Myofiber necrosis 

Regeneration + Lymphocytic inflammation of muscles 

227

What are the three disorders seen in dogs of the NMJ?

Myasthenia gravis 

Tick paralysis 

Botulism 

228

What dogs are predisposed to myasthenia gravis?

Jack russels 

Smooth fox terriers 

Springer spaniels 

 

229

What breeds of dogs are predisposed to exertional rhabdomyolysis?

Racing greyhounds 

Sled dogs 

 

230

What muscles are most affected in dogs with exterional rhabdomyolysis?

Back + Thigh muscles 

231

What breeds of dogs are predisposed to Motor neuron disease?

Brittany Spaniel 

Rottweiler

232

What is elevated in a cat with duchenne's type?

CK + AST + ALT 

233

How does x-linked musclar dystrophy present in a cat?

Progressive, presistent stiff gait 

Associated with marked muscular atrophy 

234

What does FeLV cause in cats muscularly?

Immune mediated myositis