File photo: Pigs look up from their pen at a pig farm.

Ottawa - An undercover video showing dozens of pregnant pigs in cramped and stifling conditions at a Canadian pig farm led an animal welfare group on Monday to condemn the pork industry.

The video shot for Mercy For Animals showed pigs suffering from open wounds and pressure sores from rubbing against the metal bars of their cages at a farm run by one of the country's largest pork producers.

One pig was shown tangled up in the bars, its neck broken possibly in an escape attempt, in what the welfare group summed up as “blatant animal abuse.”

The video showed pigs too sick to stand being kicked, slapped and pulled by their ears and highlighted a botched cull where a bolt gun was fired into a pig's skull but the animal did not die and was left conscious and blinking.

The video was shot recently at a farm in Arborg, Manitoba, operated by Puratone, which is a supplier for some of Canada's largest grocery chains, including Sobeys, Loblaws, Metro, and Walmart.

Mercy For Animals director Stephane Perrais told reporters 1.5 million sows live in similar conditions at factory farms all over Canada, and called on grocers to pressure the pork industry to phase out tiny gestation crates.

Animal welfare activist Temple Grandin said: “Gestation crates for pigs are a real problem... basically, you're asking a sow to live in an airline seat,” for her entire life.

The crates are so small that the pigs are unable to even turn around or lie down comfortably, she said.

Puratone said it was “disturbed by some of the images, shown in the video taken at one of our farming sites, which do not reflect our animal welfare policy and principles.”

The company has launched an investigation and promised corrective action. - Sapa-AFP