Hereditary & congenital myopathies Flashcards
Mitochondrial myopathy case report in arabian filly cause
deficiency of complex I (first step in mitochondrial respiratory chain)
What were the biochemical assay changes with mitochondrial myopathy?
increased lactic acidosis with light exercise
**no changes in CK
What clinical signs of mitochondrial myopathy were reported in case report of arabian filly?
progressive signs of muscle atrophy
marked exercise intolerance
Define glycogen branching enzyme deficiency
glycogen storage disorder causing abortion, seizures and mm weakness in QH-related breeds
What is the genetic mutation resulting in GBED?
nonsense mutation in exon 1 of the GBE1 gene at codon 102 (introduces a premature stop codon)
What is the prevalence of carriers for GBED?
9% of Quarterhorses
What percentage of horses show a higher prevalence of GBED?
pleasure horses (26%)
Glycogen branching enzyme deficiency clinical signs in foals:
hypothermia
weakness
flexural deformities of all limbs
ventilatory failure
recurrent hypoglycemia & collapse
What is the confirmatory diagnostic in GBED foals?
genetic mutation in tissue samples or by identifying typical PAS-positive inclusions in muscle or cardiac samples
Are there gross abnormalities in GBED foals at necropsy?
No
What is the muscle disease identified in charolais cattle?
deficiency in the enzyme Myophosphorylase (McArdle’s disease)
C/S with phosphorylase deficiency in charolais cattle?
exercise intolerance and collapse (when forced to exercise)
When should phosphorylase deficiency be considered as a differential?
In white muscle disease animals with normal vit E/ selenium deficiency?
What other spp see a phosphorylase deficiency than charolais cattle?
Sheep in Australia
Clinical signs of pseudomyotonia in cattle?
exercise induced muscle stiffness with normal response to percussion
**delayed mm relaxation
Pseudomyotonia in cattle has been identified in waht breeds?
chianina
dutch improved red & white crossbreed heifer
What is the genetic disorder in Hampshire pigs that reduces meat quality in pigs by increasing glycogen content of muscle?
porcine (RN-) glycogen storage disease
Muscle cramps arise from
Hyperactivity of motor units caused by repetitive firing of the peripheral and/or central nervous system
Muscle cramps can be induced by:
-Forceful contraction of a shortened muscle
-changes in electrolyte composition of extracellular fluid
-ear tick infestations in horses
Define muscle contracture
Painful muscle spasms that represent a stage of muscle contracture unaccompanied by depolarization of the muscle membrane
occur with malignant hyperthermia
What are the most common dietary electrolyte deficiencies that cause muscle stiffness, weakness and occasional elevations in mm CK?
Sodium
Potassium
Why is supplementation of the equine diet with sodium necessary?
Because forage & grain diets are low in sodium and chloride & high in potassium
