Educational materials for horse owners includes a guide to equine colors and markings, plants poisonous to horses, and calculating age from a tatoo number.

Most horses tend to avoid toxic plants, however sometimes they don't, either because they don't recognize them, they are especially hungry, or they accidentally ingest them. Younger and more curious horses are more likely to "sample" their environment, and at certain times of year toxic plants can be more lush and attractive than the native grasses which surround them. Horses under stress can be more susceptible to relatively low levels of toxicity.

Poisoning by a toxic plant can produce a number of different symptoms depending on the plant eaten, the amount ingested, the period of time over which it has been eaten, and even varies from individual horse to individual horse. It is often very difficult to diagnose poisoning in a horse primarily because many of the symptoms can mimic those of other conditions. Plant poisoning is often extremely serious and even fatal. For this reason it is important to contact a veterinarian as soon as a horse begins exhibiting any abnormal behavior thought to be caused by the ingestion of a toxic plant.

Poisonous plants can cause serious injury to horses, particularly if animals graze when plants are at an especially dangerous growth stage, when little other forage is available, and when animals are very thirsty. Poisonings can be avoided by proper management of animals, pastures, and hay. Suggestions for preventing poisoning are as follows: Know which plants are poisonous and when they are potentially dangerous; Inspect pastures to identify and destroy poisonous plants before initiating grazing; Be sure animals are neither hungry nor thirsty when put on pasture or fed hay that might have poisonous plants; Buy hay locally so that unfamiliar and potentially poisonous plants are not fed and seeds are not introduced to your farm; Do not put animals on forage that is too young in springtime; Maintain grazing pressure appropriate for the pasture; Provide supplemental feed and water to animals during periods of low pasture availability.

ProVet healthcare information article on mistletoe poisoning. Mistletoe poisoning is rare - but it does occur in dogs, horses and cattle - particularly over Christmas and New Year. In dogs it is frequently fatal and follows the ingestion of large numbers of the red fruits during the winter months.