Moulds, weed seeds, poisons and other pig health risks

Pig health can be affected by:

  • contaminated grains or weed seeds in feedstock
  • poisons
  • excess salt or mineral supplements in feed
  • lack of water
  • overdoses of medications.


Mycotoxins, such as aflatoxins and ergot, are poisons produced by moulds (microscopic fungi) growing in grains and feedstuffs. They can affect production and cause loss of pig condition, serious illness or death.

Weed seeds

Weed seeds are commonly found in grains used in pig feed. Some weed seeds are highly toxic and can cause severe illness and death. Others are non-toxic but can interfere with digestion or lower nutrient intake and reduce growth.

Warfarin (rat bait)

Warfarin (rat bait) and other anticoagulants are commonly used to control rodents in piggeries. You must not place baits in areas where pigs can eat them. Baits used in feed storage or mixing areas must not fall into feed.

Pigs affected by warfarin will bleed from a variety of sites, including under the skin (haematomas), which produces purple-blue bruises. Treatment for warfarin poisoning involves vitamin K injections or feed supplements.

Salt poisoning or water deprivation

Salt poisoning or water deprivation occurs when weaner, grower or finisher pigs are deprived of water for more than 24 hours, or consume excessive salt in either feed or water.

Causes can include water pump or delivery system failure, or water being too hot due to pipes exposed to the summer sun. Water must be re-introduced gradually to prevent deaths.


Organophosphates are registered for use in pigs to control of mange and lice. Overdosing, particularly of very young piglets, leads to poisoning. Make sure you follow the directions on the label to avoid poisoning.

Heavy metal poisoning

Heavy metal poisoning in pigs is usually due to a feed mixing error or use of contaminated ingredients. It results in excessive quantities of copper, selenium, lead, inorganic arsenic, iron or mercury in the diet.

Diagnosis is confirmed by analysis of tissue samples from dead pigs or from feed samples.