Allele and genotype frequencies of the SOD1 c.118G>A mutation associated with degenerative myelopathy in Boxer and Pit Bull Terrier dogs from Uruguay.

Canine degenerative myelopathy (DM) is a hereditary disease of the spinal cord, characterized by a progressive clinical course, and the death of affected animals. This study aimed to investigate the population distribution of the SODc.118:G˃A mutation responsible for the disease. For this purpose, 131 dogs from both breeds (Pit Bull Terrier, n=64, and Boxer, n=67) were studied. Genomic DNA was extracted from peripheral blood, and the mutation was identified using the PCR-RFLP technique. For each population, the mutant allele frequency, genotypic frequency, and Hardy-Weinberg equilibrium were calculated. The frequency of the DM-related A allele was 0.16 in the Pit Bull Terrier and 0.52 in the Boxer breed. Both populations were in Hardy-Weinberg equilibrium (p > 0.05). The genotypic distribution differed between the two breeds analyzed and also between different populations within each breed (p < 0.05). Simulation of the evolution of the mutant allele frequency under different genetic drift models showed that the variance of the allele frequency increased as the effective population size (Ne) decreased. The frequency detected in the Boxer breed was high, and although it was lower in the Pit Bull Terrier, the allele was still present. These findings support the potential use of genotyping tests for degenerative myelopathy management and provide descriptive population data from dogs of both breeds in Uruguay.