Articular Osteochondrosis in Pigs and Its Effects on Genetic Screening01 October 2014
A Norwegian study has shown that computed tomography at 159 days of age is a powerful screening tool for osteochondrosis to six months of age. At least half of the defects detected later resolved without intervention.
A significant heritability has been documented for articular osteochondrosis, according to Kristin Olstad of the Norwegian University of Life Sciences in Oslo and others there and with Norsvin.
In a paper in BMC Veterinary Research, they explain that selection against osteochondrosis has historically been based on macroscopic evaluation but as computed tomography (CT) is now used to select boars with optimal body composition, it can potentially also be used to screen for osteochondrosis. False negative diagnosis will occur if defects have not developed or have resolved prior to screening at a single time point.
The aim of the Norwegian study was to assess the suitability of the use of CT at a single point in time as a screening tool in piglets for articular osteochondrosis, which is known to be a highly dynamic condition in which lesions develop and resolve over time.
Male Landrace piglets (n=18) were serial CT-scanned from two to eight times at biweekly intervals from 70 to 180 days of age. At each interval, one or two piglets were euthanased and the left distal femur processed for histological validation.
A total of 795 defects were identified in the 112 available CT scans. Within the hind and fore limbs, the incidence of defects was highest in the stifle (n=321) and elbow joints (n=110), respectively.
Ninety-eight per cent of the defects in the stifle and elbow joints had developed by the 7th examination interval when the piglets were a mean age of 159 days old. The proportion of defects that resolved was lowest in the stifle joint at 51 per cent and highest in the elbow joint at 69 per cent.
Scanning of the current piglets at an age of 159 days resulted in detection of 98 per cent of the total number of defects that developed up to the maximum age of 180 days.
Olstad and co-authors concluded that the proportion of defects that resolved ranged from 51 to 69 per cent for different joints but may not adversely affect prevalence as this category of false negative diagnosis will result in selection of pigs that are disposed for healing.
They added that optimally timed CT is a powerful screening tool for osteochondrosis.
Olstad K., J. Kongsro, E. Grindflek and N. Dolvik. 2014. Consequences of the natural course of articular osteochondrosis in pigs for the suitability of computed tomography as a screening tool. BMC Veterinary Research. 10:212. doi:10.1186/s12917-014-0212-9