Pica is the desire to eat unusual substances that possess little or no nutritional value, such as dirt, wood, hair or faeces. Horses with pica can lick or mouth foreign substances, and in some cases ingest the materials. While the underlying cause of pica remains unknown, pica is commonly thought to be due to nutritional imbalances, such as mineral or vitamin deficiencies. Where there is no evidence of nutritional inadequacies, pica may also be the result of curiosity or boredom. In any case, pica can cause impactions that can lead to colic, prompt the formation of enteroliths in the gastrointestinal tract or cause tissue damage from the ingestion of foreign objects.
Some of the more common forms of pica in horses include ingesting faeces (coprophagia), chewing and eating wood (lignophagia), and eating soil/ dirt (geophagia).
- Geophagia, the consuming of dirt is not uncommon. While the practice is generally harmless, consuming sand can cause colic and other intestinal troubles and should be discouraged by not feeding hay off the ground or avoiding turning the horse out in sandy paddocks, if possible.
- Lignophagia is the eating of wood, including stall walls and shavings, which may indicate a lack of roughage in the diet, caused by lack of grazing, or boredom from lengthy periods of stall confinement. Feeding smaller meals more often, switching to a different type of bedding, and providing more exercise or interaction with other horses may also alleviate the problem.
- Coprophagia; the consumption of manure is most common in foals during the first few months of life. Consumption of manure can naturally introduce useful bacteria into their intestinal tract in preparation for a diet more heavily reliant on forage than milk. In mature horses, starvation or protein deficiency caused by lack of good-quality hay can result in coprophagia.
If your horse exhibits pica, you need to look at both its diet and environment for answers. Control of pica may involve providing salt and mineral supplements (such as Ranvets all-weather Salt Lick or our A-Z multivitamin Ration Balancer). If the horse’s diet is well-balanced nutritionally and a veterinary exam has ruled out the possibility of parasite infestation, then other factors such as boredom or loneliness might be the trigger. Providing horses with adequate roughage in the form of high-quality long-stemmed hay or pasture, plus allowing time for socialization with other horses can also help control or eliminate the behaviour.