New research funded through the Ontario Farm Innovation Program (OFIP) is suggesting that heart failure due to enlarged hearts may be a key reason why some pigs die on farm or during transport.
In-transit losses – pigs that die while being transported – tend to be higher during the summer months when temperatures are warmer, leading to a commonly accepted school of thought that attributes heat-related stress as a leading contributor to the mortalities.
“Now we know there is a lot more to this story and although it is still a relatively unusual condition – only about 0.06 per cent of all pigs shipped to market – we should do something about it,” explained Tony Van Dreumel, an independent veterinary pathologist and consultant who worked on the project together with University of Guelph PhD candidate Kathy Zurbrigg.
This led researchers from the University of Guelph and the Ontario Ministry of Agriculture, Food and Rural Affairs to dig deeper into the unexplained deaths, looking at 10 hearts from each of 30 southwestern Ontario pig farms through the course of the project.
Thirty per cent of the examined hearts were normal and 70 per cent had some degree of abnormality, such as overall enlargement and thickening of the heart walls. These enlarged hearts are not able to pump blood effectively throughout the body, so to compensate, they beat faster, leaving the pig with little capacity to further increase their heart rate during physical exertion. When the heart can no longer compensate, it fails.
“We realized that a large percentage of pigs dying in transit had pre-existing heart lesions, so when they are stressed during loading, transport or from heat, they go into acute heart failure – they basically die of enlarged hearts,” explained Van Dreumel. "Each farm had some affected hearts, even in pigs that made it all the way through to processing without any problems.”
More research is needed to determine the cause. The heart abnormalities identified in the study are similar to those of an inherited heart condition that has been recognized in cats, dogs, and even humans; further work by the team will try to determine if genetic factors are involved with pigs as well.
“These pigs with the enlarged hearts are basically living on the edge and any kind of stress may precipitate them to go into acute heart failure, so we are also looking at how these stress factors can be reduced on-farm and during transport,” Van Dreumel adds.
This includes having a loading chute that is level to the barn instead of requiring pigs to climb a ramp, using low stress handling techniques when moving the animals to prevent over-exertion, and transporting pigs directly from farm to processing if possible, instead of unloading and reloading at an assembly yard.
Ontario Pork, which represents pork producers in the province, helps fund research into issues like this that affect both farmers and the animals in their care.
“We want to make the in-transit process as comfortable as possible for the animals,” explains Jean Howden, Ontario Pork’s research and project coordinator. “The commitment to raising healthy animals is paramount for pork producers and indeed the value-chain from farm to transport to processing. Research that helps to address any kind of losses is a benefit to the entire industry and OFIP has enabled us to delve further into issues like this.”
Source: ACC