Members of the cherry family (including chokecherry, wild, black, and others) are trees or shrubs that usually have very showy flowers during the springtime, usually white or pink in color. Fruit is usually anywhere from red to purple in color when it is ripe.
Various varieties can be found throughout the United States. They can be found growing wild as well as being planted in landscapes.
The leaves of these plants are the most toxic part. In some species the bark is also toxic.
These plants are toxic because they produce cyanide, which is lethal to horses (and all animals). The leaves are most toxic when they are stressed or wilted, as this is when cyanide is produced.
Cyanide is created when two different components in the plant come together. In the in-tact leaf or plant part, the two components never meet. However, when the plant is destroyed in some manner (horse eating it, wilting, etc) cyanide is produced. Cyanide is lethal because it reacts with iron in your horse's body to stop cellular respiration.
It also prevents oxygen from being transported via the blood stream, so the horse essentially suffocates.
Consumption of the leaves from these plants can result in death within minutes if enough are consumed. Other symptoms include:
Unfortunately, the most common scenario is that animals are found dead in the pasture after consuming these plants because the poisoning progresses so quickly. Very rarely will other symptoms be observed, unless the animal is found immediately after consumption of the plant.
Poisoning from these plants can be treated, though very often a veterinarian is not able to arrive in time. Toxic reactions from cyanide poisoning progress extremely rapidly, so there is often not time to get the vet on site.
Images on this page are used with permission under the GNU Free Documentation License. Where available, author names appear in the lower right hand corner of the image.