Details

Common Name
Choke cherry
Botanic Name
Prunus virginiana
Plant Family
Rosaceae
Habitat
A common shrub or small tree 10-20 feet high growing along waterways in mountain valleys and occassionally in drier areas.
Animals Affected
Cattle, sheep, goats
chokecherry
Toxic Principle
Cyanogenic glycosides (prunasin,and amydalin) which are readily hydrolysed by rumen microorganisms to free hydrogen cyanide (HCN). All parts of the plant contain the cyanogenic glycosides except the ripe berries. The wilted leaves are more toxic than when fresh. The Cyanide blocks the action of the enzyme cytochrome oxidase that prevents hemoglobin from releasing oxygen to the tissues. Death results rapidly from anoxia. All members of the Prunus family including cherries, apricots, almonds, peaches and their hybrids contain cyanogenic glycosides in their stems, leaves and seeds. The concentrations of the cyanide glycosides increases when the plant is stressed by drought or frost. The cyanide potential is highest in the new growth of the plants.
Description
Shrub or small tree with greyish bark marked by lenticels. Leaves are simple, glossy, alternate, ovate with serrate margins. The white flowers are produced in cylindrical racemes that are fragrant. The berries turn purple when ripe and are not toxic except for the seeds. Similar species include Prunus pennsylvanica (pin cherrry) and P. serotina (black cherry).
Gastrointestinal
Excessive salivation, nervousness and weakness precede death.
Treatment
Without stressing the animal, sodium thiosulfate and sodium nitrite should be given intravenously. A mixture of 1ml 20% sodium nitrite and 3ml of 20% thiosulfate should be prepared and given at the rate of 4 ml of the mixture per 100lbs body weight. In ruminants Sodium thiosulfate may also be given orally via stomach by dessolving 30gm in a gallon of water.
Cardiovascular system
Sudden death. Mucous membranes appear pink and redder than normal. Venous blood is cherry red in color. Stressing the animal rapidly leads to collapse and death.
Respiratory System
Initially animals show difficulty in breathing. Open-mouth breathing is common as the animal becomes oxygen deprived. Death occurs rapidly.
Diagnosis
Sudden death with evidence of animal eating cyanogenic plants. Severe respiratory difficulty, cherry-red mucous membranes are highly suggestive of cyanide poisoning. Plant material or fresh rumen contents can be submitted for detection of cyanide (Picrate test).
Special Notes
Ruminants are most susceptible to plant-induced cyanide poisoning because their rumen bacteria and alkaline pH of the rumen quickly hydrolyze the glycosides to free cyanide, which is absorbed to cause poisoning. In simple stomached animals, including the horse, the acid pH of the stomach and the fact that horses do not have a lot of bacteria in their stomach's to breakdown the cyanogenic glycosides, means that they are not likely to develop cyanide poisoning from eating the leaves of cherries and apricots etc. Under rare situations where a horse might eat large amounts (10 lbs) of wilted cherry/apricot leaves, there may be enough cyanide present to cause poisoning. However, a horse fed a normal balanced ration, or where there is plenty of normal grass present, it is very unlikely that apricots etc. would pose any risk to horses. The mare reproductive loss (MRLS) syndrome that caused significant fetal losses in Kentucky in 2001 was initially attributed to mares eating black cherry trees (Prunus serotina), and the effects of cyanide on the fetus. However, cyanide intoxication was found not to be the cause of MRLS.Numerous research reports now indicate that the MRLS is related to the Eastern Tent catepillar that was contaminating the food and water of the pregnant mares. Further research indicates that it is the hairs from the catepillars that damage the intestinal lining of the mare resulting increased permeability that allows bacteria and/or a toxin into the circulation of the mare and ultimately the developing fetus. Ref: Bernard WV, LeBlanc MM, Webb BA, Stromberg AJ. Evaluation of early fetal loss induced by gavage with eastern tent caterpillars in pregnant mares. J Am Vet Med Assoc. 2004, 225:717-721. Ref: Levent Dirikolu et al. The Toxicokinetics of Cyanide and Mandelonitrile in the Horse and Their Relevance to the Mare Reproductive Loss Syndrome. Toxicology Mechanisms and Methods, 13: 199–211,2003.
chokecherry flowers
Choke cherries
Prunus serotina