Intestinal torsion

The cause of intestinal torsion is unknown, but may be linked to stress, whey feeding, liquid feeding and high intake of grain-based diets.

Gas produced in the intestines (bloat) leads to torsion or twisting of the large intestine. The twist rapidly starves the intestine of oxygen, causing the pig to suddenly die from shock.

Some pigs can die from bloating without the intestine twisting.

Circumstantial evidence suggests the problem is related to a low-fibre, high-energy diet. One theory is that undigested carbohydrate (usually grain such as sorghum) is fermented in the large intestine and the gas it produces causes bloat.

The lighter gas-filled large intestine, which is normally below and forward of the small intestine, flips through a 180° twist.

Occurs worldwide

Most of the time, pigs are found dead with pale skin and abdominal distension (bloat). Early signs may include:

• bloating after feeding
• pigs screaming with severe abdominal pain
• difficulty breathing
• lying down and getting up repeatedly—due to severe stomach pain which causes collapse and death in 1 to 12 hours
• sitting down like a dog.

Some commercial piggeries regularly lose pigs while others only have occasional losses.

Intestinal torsion mainly occurs between 2 and 6 months old. It can also occur in sows on liquid feed.

This disease can be detected and confirmed by post mortem.

After death, the:

• carcass is very pale, and decomposes faster than normal
• abdomen is bloated (distended)
• mucous membranes of the mouth, eye, vulva and anus are dark red.

If the pig is laid out on its right side, removing the left abdominal wall shows the small intestine in an abnormal position, forward and below the large intestine and bloated with gas.

The small intestine is heavy and contains blood (red gut, bloody gut).

If you are holding down the gas-filled large intestine, a twist in the root of the mesentery (the tissue that supports the small intestine) can be found immediately below the left kidney.

All of the pig's intestines will be attached to the abdominal wall except for the first part of the small intestine (duodenum) and the last 30cm of the large intestine and rectum. Therefore, the duodenum and the last part of the large intestine and rectum are free of blood.

The twisting blocks the thin-walled veins that drain blood from the intestine, but not the thick-walled arteries which continue to supply blood to the intestines until death.

This causes the intestines to be dark red and congested with blood after the pig dies (red gut, bloody gut).

• No known treatment or controls are available.
• Try to minimise the amount of whole grain in pig feed.
• Control intake of whey and liquid feed.
• A similar disease has been seen that was due to vitamin E deficiency, but intestinal torsion was not seen; only bloat, bloody gut and sudden death. Research is needed to determine the factors that predispose to intestinal torsion.