Objective—To perform respiratory chain enzymatic
activity assays on canine skeletal muscle biopsy specimens
and establish reference range values of skeletal
muscle enzyme activities for dogs.
Sample Population—Biopsy specimens from the
vastus lateralis muscle were obtained from 24 dogs
(8 sexually intact males and 14 sexually intact
females) ranging from 15 months to 6 years of age.
Procedure—Mean values of citrate synthase,
cytochrome-c oxidase, succinate dehydrogenase,
succinate dehydrogenase-cytochrome-c reductase,
nicotinamide adenine dinucleotide (NADH) dehydrogenase,
and NADH dehydrogenase-cytochrome-c
reductase activities were established by use of 6
standard spectrophotometric assays for respiratory
chain enzyme analysis.
Results—Compared with published data for skeletal
muscle enzyme activities in humans, skeletal muscle
enzyme activities in dogs were 2- to 4-fold higher.
Additionally, citrate synthase activity, a marker for
mitochondrial volume, was positively correlated with
age in dogs, suggesting that mitochondrial volume
increases with age, although no apparent change in
respiratory chain enzymatic activity with an increase
in age was found.
Conclusions and Clinical Relevance—Reference
range values for skeletal muscle enzyme activities of
dogs are needed to accurately interpret results of respiratory
chain enzymatic activity assays. During investigation
of metabolic myopathies, if skeletal muscle
biopsy specimens are evaluated for respiratory chain
enzyme kinetics, they should be performed and evaluated
in concert with skeletal muscle biopsy specimens
from clinically normal animals of the same
species. (Am J Vet Res 2004;65:480–484)