Hereditary & congenital myopathies

Question 1

Mitochondrial myopathy case report in arabian filly cause

Answer 1

deficiency of complex I (first step in mitochondrial respiratory chain)

Question 2

What were the biochemical assay changes with mitochondrial myopathy?

Answer 2

increased lactic acidosis with light exercise
**no changes in CK

Question 3

What clinical signs of mitochondrial myopathy were reported in case report of arabian filly?

Answer 3

progressive signs of muscle atrophy
marked exercise intolerance

Question 4

Define glycogen branching enzyme deficiency

Answer 4

glycogen storage disorder causing abortion, seizures and mm weakness in QH-related breeds

Question 5

What is the genetic mutation resulting in GBED?

Answer 5

nonsense mutation in exon 1 of the GBE1 gene at codon 102 (introduces a premature stop codon)

Question 6

What is the prevalence of carriers for GBED?

Answer 6

9% of Quarterhorses

Question 7

What percentage of horses show a higher prevalence of GBED?

Answer 7

pleasure horses (26%)

Question 8

Glycogen branching enzyme deficiency clinical signs in foals:

Answer 8

hypothermia
weakness
flexural deformities of all limbs
ventilatory failure
recurrent hypoglycemia & collapse

Question 9

What is the confirmatory diagnostic in GBED foals?

Answer 9

genetic mutation in tissue samples or by identifying typical PAS-positive inclusions in muscle or cardiac samples

Question 10

Are there gross abnormalities in GBED foals at necropsy?

Answer 10

No

Question 11

What is the muscle disease identified in charolais cattle?

Answer 11

deficiency in the enzyme Myophosphorylase (McArdle’s disease)

Question 12

C/S with phosphorylase deficiency in charolais cattle?

Answer 12

exercise intolerance and collapse (when forced to exercise)

Question 13

When should phosphorylase deficiency be considered as a differential?

Answer 13

In white muscle disease animals with normal vit E/ selenium deficiency?

Question 14

What other spp see a phosphorylase deficiency than charolais cattle?

Answer 14

Sheep in Australia

Question 15

Clinical signs of pseudomyotonia in cattle?

Answer 15

exercise induced muscle stiffness with normal response to percussion

**delayed mm relaxation

Question 16

Pseudomyotonia in cattle has been identified in waht breeds?

Answer 16

chianina
dutch improved red & white crossbreed heifer

Question 17

What is the genetic disorder in Hampshire pigs that reduces meat quality in pigs by increasing glycogen content of muscle?

Answer 17

porcine (RN-) glycogen storage disease

Question 18

Muscle cramps arise from

Answer 18

Hyperactivity of motor units caused by repetitive firing of the peripheral and/or central nervous system

Question 19

Muscle cramps can be induced by:

Answer 19

-Forceful contraction of a shortened muscle
-changes in electrolyte composition of extracellular fluid
-ear tick infestations in horses

Question 20

Define muscle contracture

Answer 20

Painful muscle spasms that represent a stage of muscle contracture unaccompanied by depolarization of the muscle membrane
occur with malignant hyperthermia

Question 21

What are the most common dietary electrolyte deficiencies that cause muscle stiffness, weakness and occasional elevations in mm CK?

Answer 21

Sodium
Potassium

Question 22

Why is supplementation of the equine diet with sodium necessary?

Answer 22

Because forage & grain diets are low in sodium and chloride & high in potassium