Muscle Flashcards
1
Q
Enzyme activities to assess muscle damage
A
Creatine kinase (CK) Aspartate aminotransferase (AST) Lactate dehydrogenase (LDH)
2
Q
What is Serum CK a sensitive indicator for?
A
myonecrosis in both skeletal and heart muscle
3
Q
When does Serum CK activity increase?
A
Increased within hours of a muscle insult and peaks within 4-6 hours after injury
4
Q
When can CK elevate?
A
training
transport
strenuous exercise
5
Q
What enzyme has high activity in skeletal and cardiac muscle as well as Liver, RBCs, and other tissues?
A
AST
6
Q
When is the peak time for AST levels after an insult?
A
24 hours
7
Q
What do elevations in CK and AST reflect?
A
recent or active myonecrosis
8
Q
What do elevations of CK reflect?
A
myonecrosis is likely going on
9
Q
What do elevated AST and decreasing or normal CK levels indicate?
A
Myonecrosis not continuing
10
Q
Elevations in LDH specify what?
A
rhabdomyolysis
myocardial necrosis
hepatic necrosis
11
Q
What tests assess concurrent renal disease?
A
Urine specific gravity White blood cell count Protein content Red Blood cell count Evaluation of cast formation
12
Q
What does a positive Hemastix test in the absence of hemolysis or RBCs in urine indicate?
A
Myoglobinuria
13
Q
Exercise Challenge test
A
15 mins of slow trot with CK activity sampled before and 4-6 hours after
14
Q
What do elevations of greater than 5-fold CK indicate?
A
exertional rhabdomyolysis
15
Q
Electomyography
A
to detect spontaneous or evoked potentials of neurogenic or myogenic
16
Q
What do horses with abnormalities show on electromyography?
A
Spontaneous electrical activity
Fibrillation potentials: spontaneous firing of muscle fibers
Positive sharp waves
Myotonic discharges: bursts of complex high-frequency potentials
Complex repetitive discharges
17
Q
What are EMG and NCVs used to classify?
A
classify the disease Neuropathic or Myopathic
18
Q
Use of Nuclear Scintigraphy
A
ID some forms of muscle damage
area of deep muscle damage
19
Q
How does Nuclear Scintigraphy work?
A
Technetium 99 m methylene diphosphonate is taken up in inflamed and damaged muscle
20
Q
How is muscle fiber disruption seen on Ultrasonography?
A
hypoechoic area with loss of the normal fiber striation
21
Q
How do es a defect in muscle/hematoma appear on ultrasonography?
A
Hypoechoic
22
Q
How does increased connective tissue or loss of muscle appear on ultrasonography?
A
Hypoechoic
23
Q
How does mineralization or gas pockets appear on ultrasonography?
A
Hyperechoic shadowing artifacts
24
Q
“Sweeney”
A
suprascapular nerve is damaged and muscle over the scapula are atrophied
25
How long does it take for denervation to result in 50% muscle mass loss?
2 - 3 week period
26
What are the causes of Atrophy?
Denervation
Disuse
Malnutrition and cachexia
Immune-mediated myositis
27
HYPP
Hyperkalemic Periodic Paralysis
28
What causes HYPP?
inherited defect in the skeletal muscle sodium channel
29
What type of trait is HYPP?
Autosomal dominant
30
What does HYPP cause?
Abnormal skeletal muscle membrane excitability leads to episodes of myotonia, muscle contraction, and paralysis
31
What can trigger an episode of HYPP?
Ingestion of diets high in potassium, alfalfa hay, molasses
Electrolyte supplements
Sudden dietary changes and fasting
Anesthesia, heavy sedation or trailer rides
32
What are the clinical signs of an episode of HYPP?
Myotonia
prolapse of the third eyelid
Sweating
muscle fasciculations in the flanks, neck, and shoulders and then become generalized
Respiratory distress due to paralysis of the upper respiratory muscles
dysphagia
33
What are the clinical pathological signs seen in horses with HYPP?
Hyperkalemia
Hemoconcentration
Mild hyponatremia
34
How do you control HYPP?
Decreasing dietary potassium and increasing renal losses of potassium
Avoid high potassium feeds
Regular exercise
Balanced minerals
Commercially available complete feeds with a guaranteed Potassium content
35
What drugs are used to control horses with HYPP?
Acetazolamide
36
Acetazolamide
stabilizes blood glucose and potassium by stimulating insulin secretion
37
Muscle Cramping
painful condition that arises from hyperactivity of motor units cause by repetitive firing of the peripheral and/or central nervous system
38
What is the cause of Muscle cramping?
Dehydration
Electrolyte abnormalities
Disturbances in thermoregulatory and local circulatory function
39
What deficiency is common in horses?
Sodium
40
What deficiencies can result in muscle stiffness, weakness, and occasional elevation in CK?
sodium or potassium
41
What is a common muscle condition seen in endurance horses?
Muscle cramping
42
What are the common electrolyte abnormalities of exhaustion?
hypochloremic metabolic alkalosis with hypokalemia, hypomagnesemia and low serum ionized calcium
43
What can be seen with muscle cramping in horses?
Synchronous diaphragmatic flutter
44
What is the treatment for muscle cramping?
Signs abate with rest or light exercise
oral or intravenous polyionic fluids
Cooling horses down with water and fans
Supplement with sodium chloride and potassium chloride
45
What are the two types of Rhabdomyolysis?
Non-exertional
| exertional
46
Clostridial Myonecrosis
Disease characterized by a rapid clinical sourse, fever, systemic toxemia, and high mortality
47
Clinical signs of Clostridial Myonecrosis
```
Crepitus
Malodorous serosanguinous fluid
Tremors
Ataxia
Dyspnea
recumbence
coma
death within 12-24 hours
```
48
What is the cause of Clostridial Myonecrosis?
Recent injection
49
What is a site of invasion for Clostridium in foals?
Umbilicus
50
What is the treatment for Clostridial myonecrosis?
Antibiotic therapy
Aggressive surgical debridement
supportive care
51
What is the drug of choice for treatment for Clostridial myonecrosis?
Penicillin
52
Clinical signs of Rhabdomyolysis associated with Streptococcus
Stiff gait
| rapidly to markedly firm, swollen painful epaxial and gluteal muscles
53
What are the two causes of Rhabdomyolysis/ Streptococcus equi?
1. Toxic Shock
| 2. Bacteremia
54
What is the treatment for Rhabdomyolysis/ Streptococcus equi?
Flushing infected guttural pouches and draining abscessed lymph nodes
NSAIDs
CRI of lidocaine, detomidine, or ketamine
55
What are the clinical signs of Immune-mediated polymyositis?
Rapid onset of muscle atrophy of the back and croup muscles
accompanied with stiffness
Generalized weakness
56
What do you see on biopsy of Immune mediated Polymyositis?
lymphocyte vasculitis
angular atrophy
fiber necrosis with macrophage infiltration
regeneration
57
What is the treatment for Immune Mediated Polymyositis?
Corticosteroids
58
What viruses are associated with myopathy?
Equine Influenza A2
| EHV1
59
What muscles are affected by virus associated myopathy?
Skeletal muscles and cardiac muscles
60
Seasonal Pasture Myopathy and Atypical Myopathy
a highly fatal acquired lipid storage myopathy of pastured horses kept on wooded pastures for more than 12 hours a day without additional feed
61
What are the clinical signs of Seasonal Pasture Myopathy and Atypical Myopathy?
```
Acute muscular weakness
Sweating
fasciculations
stiffness
tachycardia
tachypnea
recumbence
myoglobinuria
```
62
What are the clinical pathological signs of Seasonal Pasture Myopathy and Atypical Myopathy?
increase in CK and AST activity
hyperglycemia
lactic acidemia
63
How do you diagnose Seasonal Pasture Myopathy and Atypical Myopathy?
Identified deficiency in multiple acetyl coA dehydrogenase
Isolation of the conjugated toxic metabolite methylenecyclopropyl acetic acid in blood or urine
Extensive necrosis in deep postural, respiratory muscles and myocardium
64
What is responsible for causing Seasonal Pasture Myopathy and Atypical Myopathy
Seeds of Acer species trees such as the box elder containing toxic amino acid hypoglycin A
65
What is the paathophysiology of the Seed of Acer species tree?
Hypoglycin A is metabolized in the liver to MCPA
MCPA irreversibly binds to multiple enzymes that are essential for metabolism fatty acids and branched chain amino acids
Accumulation of fat esters can damage muscle cell membranes, and an energy deficiency also arises from an inability to metabolize fat
66
What is the treatment and control of Seasonal Pasture Myopathy and Atypical Myopathy
Early aggressive supportive care
| Avoid pasture with Acer species trees
67
What are the two forms of Postanesthetic Myoneuropathy
Localized myopathy-neuropathy
| Generalized myopathy
68
Localized myopathy-neuropathy
occurs in muscles that are in contact with a hard surface or with compromised arterial blood supply
69
What is the cause of Postanesthetic Myoneuropathy?
Duration of anesthesia, ischemia, and hypoperfusion as a result of prolonged immobility, muscle compression, systemic hypotension, and hypoxia
70
What is the treatment for Localized myopathy-neuropathy?
Supportive care
| Anti-inflammatory drugs
71
How do you control localized myopathy-neuropathy?
Goo padding and proper placement of limbs and body to reduce pressure
Maintaining anesthesia at the lightest plane possible and adequate arterial blood pressure
72
What are the clinical signs of Generalized Anesthetic Reactions?
```
Anxiety
hyperthermia
tachycardia
tachypnea
profuse sweating
myoglobinuria
```
73
What are the aims of treatment for myopathy-neuropathy?
Relief of pain
Correction of fluid and electrolyte abnormalities
Attempts to prevent ongoing necrosis
High-quality nursing care
74
What is used to release calcium from the sarcoplasmic reticulum helping to break the cycle of muscle damage from myopathy-neuropathy?
Dantrolene
75
What myopathy is common in jumpers, dressage, harness horses and thoroughbreds?
Exertional myopathies of the lumbar and gluteal muscles
76
What myopathy is common in Quarter horses?
Strain semitendinosus and semimembranosus muscles
77
What is caused by chronic exertional myopathies?
fibrotic myopathy
78
What is a clinical sign of strain the semitendinosus and semimembranosus muscles?
Stride has a short anterior phase with a characteristic hoof-slapping gait
No pain
79
How do you treat strain of semitendinosus and semimembranosus muscles?
Surgical procedures fro correction of fibrotic myopathy
| excision or transection of the fibrotic part of the muscle
80
What is the most common muscle disorder of horses?
Sporadic Exertional Rhabdomyolysis
81
What are the clinical signs of Sporadic Exertional Rhabdomyolysis?
Stiff gait
excessive sweating
high respiratory rate during or after exercise with firm painful muscles after 15-30 minutes of light exercise
Myoglobinuria
82
How do you diagnose Sporadic Exertional Rhabdomyolysis?
abnormally elevated serum CK and AST
| Myoglobinuria
83
What causes Sporadic Exertional Rhabdomyolysis?
Level of exercise
Signs of muscle stiffness and gait changes
Severity of elevations of serum CK activity
84
What dietary imbalance exacerbates Sporadic Exertional Rhabdomyolysis?
selenium and vitamin E
85
How do you treat Sporadic Exertional Rhabdomyolysis?
```
Anti-inflammatories
Sedative or tranquilizer
Fluid therapy
Muscle relaxants
Nutrition
```
86
What can severe rhabdomyolysis lead to?
Renal damage due to combined nephrotoxic effects of myoglobinuria, dehydration, and NSAIDs
87
How do you treat Sporadic Exertional Rhabdomyolysis?
Stall rest
Resume training gradually
Avoid excessive calorie intake and ensure proper nutritional balance
88
What triggers Recurrent Exertional Rhabdomyolysis?
Exercise
89
What are the clinical pathological findings of Recurrent Exertional Rhabdomyolysis??
Rise in serum CK and myoglobin
| Rise in Cortisol concentrations
90
How do you diagnose Recurrent Exertional Rhabdomyolysis?
Biopsy
91
What type of diet should horses be on to manage Recurrent Exertional Rhabdomyolysis?
Low-starch High-fat concentrates
92
What is discouraged for horses with Recurrent Exertional Rhabdomyolysis predisporsition?
Days off training in a stall
93
What medications are used to help control Recurrent Exertional Rhabdomyolysis?
```
Acepromazine
Reserpine
fluphenazine
Dantrium sodium
Oral Dantrolene
Phenytoin
```
94
Polysaccharide Storage Myopathy
horses have 2-fold higher glycogen concentration than normal horses and abnormal granular amylase-resistant inclusion in histiologic sections because of a malfunction in glycogen synthase enzyme due to a single base-pair mutation in GYS1
95
What is the common trigger for Type 1 Polysaccharide Storage Myopathy?
Exercise
96
How do you diagnose Type 1 Polysaccharide Storage Myopathy?
Elevated serum CK and AST
Exercise test produce a minimum of a three fold elevation in CK activity 4-6 hours after exercise
Muscle Biopsy
