Chewing rails, feeders and doors is a common habit in horses confined to stables and yards when fed mainly on concentrate diets. Horses at pasture will occasionally chew rails and trees, particularly during wet or cold weather.
Many horses will chew and may ring bark young trees in early spring, presumably because the sweet juicy sap is flowing, or pasture is lush and succulent with a lower fibre content. it is also possible that the high soluble starch intake on lush pasture leads to a hind-gut overload and fermentation with acid production, which irritates the gut, causing the horse to seek fibre to eat.
Most horses prefer to chew soft woods, including treated pine rails, plywood and particleboard. Observations indicate that a stabled horse spends an average of 8 minutes per day chewing stall fixtures. Although most of the wood chewed is not swallowed, splinters of wood may lodge between the teeth or lacerate the gums or tongue.
Wood chewing also wears away the front edges of the upper and lower incisor teeth. A horse confined to an outside steel fenced yard may develop a habit of licking the pipes, wearing off the paint and exposing the metal, which then rusts.
Breed
Some studies identified Standardbreds, Thoroughbreds, Arabs and Warmbloods as having more frequent colics that other breeds, while other studies found the opposite was true. There are no proven trends.
Age
There is some evidence that more colics occur in horses between the ages of two and ten. Consider: these are the years of heavy training and performance. Horses may be under stress form frequent travel, competitions and changes in schedule.
Use
One study showed a higher risk of colic in eventers than in horses used for other sports. Another indicated that colic was more common in breeding stock than in pleasure horses. Consider: colonic twists are common in broodmares, and heavy lactation may induce dehydration or electrolyte imbalance.
Pasture/Stall
Horses pastured 24 hours a day have low rates of colic, and risk rises as stall time increases. Consider: stalled horses may get less exercise, eat less fresh forage and be under increased stress from boredom and lack of companionship.
Caregiver
Horses cared for by owners had fewer colics than horses cared for by trainers or managers. Consider: horses cared for by a trainer are somewhat more likely to be under stress because of exercise schedule, decreased turnout and a high-grain diet.
Concentrate portion of diet
Any inclusion of grain or concentrate increased colic risk over forage-only diets. Risk was greater as the amount of concentrate increased, even if the concentrate was split into several feedings per day. The highest risk was seen when horses ate pellets; a sequentially decreased risk was noted with consumption of whole grains (oats, barley), sweet feed and a combination of whole grains and processed feeds. Horses that were given more or less than their normal grain ration, a different type of grain, or any amount of mouldy grain had increased risk of colic.
Forage portion of diet
Horses getting 100% of their forage from grazing had the lowest incidence of colic. Horses that had hay added to their diet in the previous two weeks were at higher risk, as were horses starting into a new batch or a different type of hay. Orchard grass hay was linked with colic more frequently than alfalfa, coastal or Bermuda hay. Hay from round bales are associated with an increased colic risk. Feeding hay or grain on the ground was not identified as a colic risk factor.
Water
Water deprivation increased colic risk. Stall-kept horses with automatic waterers had more colic cases than horses watered from buckets. Consider: is it difficult to keep track of water consumption with automatic waterers, so an owner might not know if a horse had stopped drinking or had decreased its water intake. Horses should always have access to fresh, clean water.
History of previous colic
Horses that had been treated for colic were ore likely to have another episode than horses that had never suffered from colic. Consider: management strategies that led to the first colic could, if not modified, leave the horse at risk for further episodes. If colic surgery was done, adhesions or other complications could lead to another attack.
Other factors
Risk was somewhat higher for horses that had stable vices; were non-aggressive or at the bottom of the herd’s pecking order; grazed rocky soil; were given more than two types of supplement; were fed bran either daily or weekly; had been given antibiotics, bute or other drugs in the previous 30 days; had been de-wormed in the previous two weeks; or had health problems other than colic.
