Testing for a Genetic Association with Heart Lesions in Market Hogs That Died In-Transit to an Ontario Abattoir

The number of pigs that die in-transit increases during the summer months in Canada and as such the cause of death has been assumed to be heat stress.  An initial study by part of this team determined that the majority of hogs that died in-transit to an abattoir had cardiac abnormalities.  These cardiac lesions were comparable to hypertrophic cardiomyopathy (HCM), a genetic heart disease recognized in humans, dogs and cats. The goal of this research was to determine if there are genetic differences between pigs with HCM-like and normal hearts. Post-mortems on 93 in-transit loss (ITL) hogs were performed at the Animal Health Laboratory, University of Guelph. Hearts from 67 hogs that did not die in-transit were collected for comparison. Each heart was weighed and examined for gross and histological lesions by a veterinary pathologist.  A DNA sample from 38 ITL hog hearts and 34 hearts of hogs that did not die in-transit were submitted for genotyping to GeneSeek (Lincoln, Nebraska) using the Illumina 60K SNP chip.  Genotypes were screened for accuracy and analysed for genome wide associations with the in-transit losses.  More than 10 regions (40 associations) associated with death were found on chromosomes SSC 1, 2, 4, 5, 7 11, and 14. Regions on SSC 2 and 14 contained genes previously associated with HCM in humans (CSRP3 and MYL2, respectively). Ignoring death status and investigating pathological heart characteristics revealed stronger genetic associations. While these analyses are preliminary it appears that the cardiac lesions have a genetic association.