The distillation of coal tar and crude petroleum products produces a variety of substances including creosols or phenolic compounds, crude creosote and pitch. These substances are used as disinfectants and preservatives and may be eaten by pigs. Pitch is used as a binder in clay pigeons and it only requires 10-15g ingested over a seven day period to produce mortalities. Tar papers, bitumen on floors and creosote treated wood are further sources of poisoning. Coal tar preparations are also irritant to the skin.

Clinical signs

The first signs of clay pigeon poisoning are prostration or coma leading rapidly to sudden death. Pigs may be found dead.

Low levels of intake interfere with the absorption of vitamin A and produce signs of deficiency including piglet malformation and stillbirths. If the skin of a newborn piglet comes into contact with phenolic disinfectants, contact areas, particularly the teats and soles of the feet may be burnt.

Diagnosis

This includes a history of access to phenolic and other coal tar preparations. Look for evidence of contamination particularly in outdoor pigs.

Treatment and control

• There is no effective treatment.
• The environment should always be examined for evidence of exposure particularly where sows are outdoors.
• Injections of vitamin A using multi-vitamin preparations may be of value.