Lignophagia is the

abnormal behaviour Abnormality (or dysfunctional behavior) is a behavioral characteristic assigned to those with conditions that are regarded as rare or dysfunctional. Behavior is considered to be abnormal when it is atypical or out of the ordinary, consists of un ...

of chewing and eating

wood Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...

. It has been recorded in several species, but perhaps most commonly in

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

s where it is usually called, simply, "wood chewing". Lignophagia is a form of the pica disorder, in which normally non-nutritive substances are chewed or eaten. For some animals, wood is the normal primary food source; such animals are known as

xylophagous Xylophagy is a term used in ecology to describe the habits of an herbivorous animal whose diet consists primarily (often solely) of wood. The word derives from Greek ''ξυλοφάγος'' (''xulophagos'') "eating wood", from ''ξύλον'' (') ...

. A related stereotypy in horses is cribbing, where a horse grabs a board or other edged object with its teeth, arches its neck and sucks in air. While this activity may cause some tooth marks on the surface used, this is not the same disorder as lignophagia.

Etymology

Lignophagia is derived from the Latin ''lignum'', meaning "wood", and the Greek ''phago'', meaning "to eat".

In horses

Horses often gnaw on wood rails, fences or boards as if they were food. This has been linked with dietary deficiencies, and often can be remedied with a balanced diet or dietary supplementation. Lignophagia in horses can be a cause of

colic Colic or cholic () is a form of pain that starts and stops abruptly. It occurs due to muscular contractions of a hollow tube (small and large intestine, gall bladder, ureter, etc.) in an attempt to relieve an obstruction by forcing content out. ...

due to the ingestion of wood splinters, and in severe cases, can cause excessive wearing and deterioration of the teeth. A related vice is cribbing, wherein the horse grabs a wood board and sucks in air; not all wood-chewing is cribbing and though cribbing may also result in chewing on the wood surface, the two vices are not identical. Colic can be a consequence of wood chewing due to the ingestion of wood splinters. Both cribbing and wood chewing can cause excessive wearing and deterioration of the teeth in severe cases. Horses displaying these behaviors may be less desirable to potential buyers and may be devalued as a consequence. Wood chewing also is destructive to barns and fences, sometimes requiring costly repairs and ongoing maintenance. Wood chewing has been linked with dietary deficiencies, and often can be remedied with a balanced diet or dietary supplementation. Some cases are thought to be linked to boredom or anxiety, often related to confinement.

In dogs

Dogs sometimes eat wood which can have negative consequences. Sometimes they will chew the furniture of their owners meaning items must be replaced. Splinters may lodge in the mouth, gums or tongue, causing a depressed appetite. The wood can perforate or block the

oesophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to th ...

or the intestine, often requiring surgery. Chemically treated wood can result in poisoning. A potential cause for lignophagia in dogs is being confined in an area with wet wood and having a diet lacking in proper nutrition.

In humans

Humans sometimes chew or eat wood, e.g.

pencils A pencil () is a writing or drawing implement with a solid pigment core in a protective casing that reduces the risk of core breakage, and keeps it from marking the user's hand. Pencils create marks by physical abrasion, leaving a trail ...

. In humans, eating wood is sometimes referred to as xylophagia.

References

{{Ethology Abnormal behaviour in animals Ethology