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Pet Owner Version

Coal-tar Poisoning


Gary D. Osweiler

, DVM, MS, PhD, Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University

Reviewed/Revised Oct 2020 | Modified Nov 2022

Coal-tar poisoning is often caused by chewing on or eating items that contain coal tar. Typical sources are clay pigeons, tar paper, creosote-treated wood, and bitumen-based flooring. Effects include liver damage with signs of jaundice, fluid build-up within the stomach, anemia, and death. Coal-tar related poisoning has been reported in farm animals and pets.

Coal tar contains 3 toxins: phenol, cresol, and pitch. Phenol is the most important toxin in coal-tar products. Cresols are used as disinfectants and are readily absorbed through the skin. Cats are especially sensitive to both phenol and cresol. Because cresol is toxic to wood-destroying fungi and insects, it is used as a wood preserver. Pitch is used as a binder in clay pigeons, road asphalt, insulation, tar paper, and roofing compounds. It is also used to cover iron pipes and to line wooden water tanks.

Diagnosis of coal-tar poisoning requires excluding poisoning by toxic plants and deficiency of vitamin E or selenium. Fragments of clay pigeons, tar paper, or other sources of coal tars found in the gastrointestinal tract, or chemical detection of coal-tar products in the liver, kidneys, blood, or urine can confirm the diagnosis.

There is no specific antidote for coal-tar poisoning. Supportive treatment is helpful, along with activated charcoal and medicines that cause the bowels to empty to reduce absorption. Antibiotics and high-quality protein diets may help recovery.

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