Abstract:
Canine degenerative myelopathy (DM) is a progressive disease process that is diagnosed
late in life and mainly affects the pelvic limbs. Factors that make an ante-mortem definitive
diagnosis of DM include: an insidious onset and clinical manifestation that mimics other
disease processes of the pelvic limbs (hip dysplasia, cranial cruciate ligament rupture, etc.) or
there may even be concurrent disease processes, old-age onset and lack of reliable diagnostic
methods. Until recently, South African dog owners had to submit samples to laboratories
overseas for genetic testing in order to confirm an affected dog (homozygous A/A) and to
aid in the ante-mortem diagnosis of DM. Only affected dogs have been confirmed to manifest
the clinical signs of DM. This study aimed to verify whether genetic testing by a local genetic
laboratory was possible in order to detect a missense mutation of the superoxide dismutase
gene (SOD1) that is implicated in causing the clinical signs of DM. The study also aimed
to detect and map the inheritance of this disease process in a local Boxer dog population
where the pedigree of the sampled population was known. Venous blood collected from
Boxer dogs using a simple random sampling technique. The samples were genotyped for the
SOD1:c.118G>A polymorphism. Carrier and affected Boxer dogs were detected. A pedigree
that demonstrated the significance of inheriting a carrier or affected state in the population was
mapped. The present study concludes that genotyping of the missense mutation in Boxer dogs
is possible in South Africa. There are carrier and affected Boxer dogs in the local population,
making DM a plausible diagnosis in aged dogs presenting with pelvic limb pathology.
