Chokecherry (Prunus virginiana
) is a perennial, deciduous, woody, thicket-forming large erect shrub or small tree. It has dark green, glossy leaves that are oval to broadly elliptical in shape with toothed margins. They are arranged alternatively and turn yellow during the autumn season. P. virginiana
initially has gray to reddish brown bark which as it ages, turns darker into a brownish-black color. In the spring, it produces aromatic flowers from April to July. A couple months after blossoming, it develops dark red to black colored sperical drupes of berries.
Chokecherry tree parts contain two main cyanogenic glycosides, prunasin in the vegetative organs (leaves, flowers, roots, bark, twigs) and amygdalin exclusively in seeds or pits. Chokecherry trees usually only contain small amounts of these compounds, so unless horses consume an excessive amount of the plant parts, cyanide poisoning is highly unlikely. However, young, rapidly growing leaf tissue and seeds tend to contain increased amounts of cyanogenic glycosides. Toxicity levels increase during periods of frost, drought, application of 2,4-D herbicides, nitrate fertilization, seasonal wilting, or wind damage following storms. As cyanide release requires hydrolysis in the gastrointestinal tract, features of poisoning may be delayed for a few hours.
Consumption of 0.25% of the horse's weight (2.5 lb for a 1000-lb horse) of fresh green leaves can be fatal.