The direct answer for a Tennessee Walking Horse
A Tennessee Walking Horse should not be fed food made for other kinds of pets, and the distinction between pet foods and livestock feeds matters here. Dog and cat foods are concentrated, animal-protein-rich products built for carnivores; a Walker's stomach and hindgut are built for near-constant fibre, so rich food arrives as an unwelcome shock to the system. Feeds mixed for cattle, sheep or poultry sit in a more serious category, because some contain additives approved for those species that are dangerous to any horse. A Walker that snatches a dropped dog biscuit needs no panic, but no other animal's ration should ever be served to it deliberately or by a helper's mistake.
How a Walker usually gets into the wrong feed
A Tennessee Walking Horse typically meets the wrong feed through the social life of a barn rather than through its own bucket. Barn cats are fed on feed-room floors, dogs carry biscuits into aisles, and a horse tied outside a tack room can reach an open sack left by someone unloading a delivery. Walkers are curious, food-motivated horses, and a loose horse on a yard investigation will sample every open container in reach. The risk rises at shows and trailheads, where neighbouring camps feed several species within a few metres of tied horses. Closing sacks, feeding pets behind doors and never leaving bowls in aisles removes most of the opportunity in one habit change.
Signs a Walker has eaten something unsuitable
Signs that a Tennessee Walking Horse is struggling after eating the wrong food centre on the gut: fewer or drier droppings than normal, pawing at the ground, looking at the flank, repeated rolling, sweating without work, or leaving its own hay untouched. A Walker in work may also feel dull and unwilling under saddle the following day if its digestion is unsettled. Record what was eaten and your best estimate of the amount, and keep the packaging if the feed is unfamiliar, because identification guides the advice you will be given. Discomfort signs, a known livestock feed, or a large quantity of anything concentrated all justify an immediate veterinary call rather than a wait-and-see evening.
Why 'just a little' still does not belong in the ration
Owners sometimes reason that a handful of another animal's feed cannot hurt a Tennessee Walking Horse, and as an accident that is usually true, but as a habit it undermines the ration in quieter ways. The Walker's diet is balanced as a whole; regular extras of rich pet food skew energy and protein in directions nobody measured, and a horse that learns to mug people for biscuits becomes harder to handle around children and other horses. There is also the simple identification problem: in poor light, one brown pellet looks much like another, and casual sharing blurs the line that keeps a genuinely dangerous livestock feed out of the wrong bucket. Horse feed for the horse is a rule with no useful exceptions.
Keeping the Walker's feed room disciplined
A Tennessee Walking Horse's protection against other feeds is a disciplined feed room that every user of the barn understands. Bins labelled by horse and by species, a scoop living in each bin, pets fed in a closed room, and deliveries checked against the order before anything is tipped away will prevent nearly every cross-feeding incident. When a mistake does happen, write it down with the time and the feed involved, so the horse can be watched intelligently rather than anxiously. On KinsLe, Care Teams can assign the nightly feed-room close-down to a named person and log any incident against the Walker's duties, so the next handler starts the morning knowing exactly what occurred.