Sources and Symptoms of Animal Poisoning

By Jon Geller and Dvm
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Certain soil imbalances can lead to pasture grasses with too much of one mineral, which can be toxic to livestock.

If your livestock or pets are acting sick or strange, they may have been poisoned by a common toxin. This chart details the most common sources and symptoms of animal poisoning.

1. Water Contamination


  • Occurs when dense bloom of blue-green algae produces potent neurotoxin.
  • Causes convulsions and sudden death in livestock, wildlife and birds.
  • Algae sampling and testing required to confirm poisoning.


  • Occurs when animal ingests high concentrations of salt or is deprived of water, especially in hot weather or in cold weather when water freezes.
  • Poultry, feeder pigs and ruminants are susceptible.
  • Blindness, deafness or paralysis may result.

2. Soil Imbalances


  • Occurs when livestock consume high selenium content in forage on alkali soil found on Great Plains of U.S., western Canada and Mexico.
  • In its most severe form, causes blindness and staggering. Can also cause cracked hooves and lameness.
  • Soil testing recommended for diagnosis.


  • Caused by imbalance in copper/molybdenum ratios in soil, most common in western U.S.
  • Ruminants, especially young cattle, are most susceptible.
  • Causes severe scours and emaciation.

3. Feed Contamination


  • Excess pigment found in cottonseed products causes cumulative toxicity.
  • Immature ruminants and pigs are most susceptible.
  • Prolonged exposure causes weight loss, weakness and loss of appetite.


  • Caused by abrupt addition of feed-grade urea or ammonium salts to the ruminant diet.
  • Mature ruminants are most susceptible, as they convert nonprotein nitrogen to ammonia, which is toxic.
  • Causes muscle tremors, weakness, difficulty breathing and death.


  • Worldwide problem caused by ingestion of moldy feed, corn, or certain varieties of mold-infected pasture grass and forage (e.g., fescue grass, rye, sweet clover).
  • All species of livestock, horses and poultry are susceptible.
  • Wide variety of signs are possible, including lameness, paralysis, listlessness, jaundice and internal bleeding.
  • Feed analysis required to confirm toxicosis.


  • Found in feed-grade phosphates, well water with high levels of fluorine or airborne factory waste.
  • Usually requires long-term exposure and results in abnormalities of the skeleton and teeth.
  • Signs may include mottling and staining of the teeth or softening of bones.


  • Usually the result of improperly formulated mineral mixes or certain plants causing mineral imbalances.
  • Primarily affects sheep.
  • Signs are related to liver damage and include diarrhea, pain, dehydration, jaundice and blood in the urine.


  • Caused by blister beetles, primarily in the southwestern U.S.
  • Beetles swarm in alfalfa hay during harvesting and are ingested by horses, sheep or cattle.
  • Signs include salivation due to oral ulcers, abdominal pain, shock and blood in the urine.

4. Farm Supplies


  • Very common culprit in farm animal poisonings.
  • Found in paint, batteries, grease and used motor oil.
  • Most common in cattle and dogs, but all animals may be affected.
  • Symptoms include dullness, lack of coordination, blindness or convulsions.

Coal Tar

  • Found in tar paper, creosote-treated wood, clay pigeons and tarbased flooring.
  • Pigs often affected after chewing treated wooden farrowing crates; cats are very sensitive as well.
  • Neurological signs, weakness, collapse and sudden death are often seen.
  • May also cause decreased growth rate in young pigs.

5. Household Poisons


  • The obromin in unsweetened baker’s chocolate can cause severe illness; cases usually involve dogs.
  • Five ounces of baker’s chocolate can be fatal to a 20-pound canine.
  • Typical signs are nervousness, vomiting, diarrhea, seizures and occasionally coma.


  • Most often involves holiday poisonings of kittens and puppies chewing on poinsettias, Easter lilies, mistletoe, philodendrons, spider plants and others.
  • Signs vary widely, but often include vomiting and neurological symptoms
  • Toxicity varies greatly among individual plants.

Cleaning Supplies and Medications

  • Bored, young or inquisitive dogs may chew through plastic bottles and pill containers.
  • Most household cleaners will cause severe vomiting and diarrhea.
  • Tylenol, Advil, Aleve and other over-the-counter medications may be toxic and potentially fatal to cats and dogs.