46. WILD BLACK CHERRY

Prunus serotina

(rose family)

TOXICITY RATING: High.

ANIMALS AFFECTED: All animals may be affected. Ruminants (cattle, sheep, goats, deer) are more at risk than monogastric animals (dogs, cats, pigs, horses) and birds.

DANGEROUS PARTS OF PLANT: Damaged leaves pose the greatest risk. All parts are potentially toxic.

CLASS OF SIGNS: Anxiety, breathing problems, staggering, convulsions, collapse, death (which may be sudden).

PLANT DESCRIPTION: This cherry may grow as a tree or shrub. Bark of young branches and twigs is scaly and reddish-brown with prominent cross-marks ("lenticels"). Leaves (fig. 46) are alternate, simple, elliptic-pointed, leathery in texture, and finely toothed on the margins. Flowers are showy, fragrant, and white, hang in drooping clusters, and produce dark-red to black cherry fruits (fig. 46A). The wild black cherry commonly grows in fence rows, roadside thickets, and rich open woods.

SIGNS: Black cherry contains cyanogenic precursors that release cyanide whenever the leaves are damaged (frost, trampling, drought, wilting, blown down from the tree during storms). Most animals can consume small amounts of healthy leaves, bark and fruit safely; however when hungry animals consume large amounts of fresh leaves or small amounts of damaged leaves (as little as 2 ounces), clinical cases of poisoning will occur, and many animals may die. This is especially true if there is no other forage for the animals to consume, or in the case of pets, when confined and/or bored, the chances for toxic levels of ingestion can occur. The conditions of cyanide poisoning have also been discussed under Johnsongrass.

Healthy cherry leaves contain prunasin, a cyanide precursor that in itself is non-toxic. When the leaves are damaged, the prunasin molecule is split and free cyanide (also called prussic acid or hydrocyanic acid) is liberated. Many plants, especially those in the rose family, have the potential to produce toxic levels of cyanide under certain conditions. Chokecherry (Prunus virginiana) is also toxic. There are reports of peach sprouts, leaves, and pits poisoning sows. Apricot pits and apple seeds are toxic as well. Arrowgrass (Triglochin maritima) contains a cyanogenic glycoside and has caused poisoning in livestock. Johnsongrass, discussed earlier, has a similar toxicity.

Cyanide prevents the body from being able to utilize oxygen at the cellular level, so although the animals physically can breath, their tissues and cells "suffocate". After consumption, signs will manifest within a few minutes, but sometimes up to an hour may pass. The animals will try to breath more rapidly and deeply, and then become anxious and stressed. Later, trembling, incoordination, attempts to urinate and defecate and collapse is noted, which can proceed to a violent death from respiratory and/or cardiac arrest within a few minutes to an hour. If an affected animal is still alive 2 or 3 hours after consumption, chances are good that it will live.

FIRST AID: The clinical signs of cyanide poisoning tends to come on quite rapidly, and the animals may be found dead without much warning. If the animals are exhibiting toxic signs, call a veterinarian immediately. There is an antidote, but it needs to be given intravenously and within a few minutes of the onset of signs, and it is often impossible to get help in time. Prevent the animals (especially the unaffected animals) from eating any more of the grass or feed. Do not handle or stress affected animals any more than absolutely necessary, since this will worsen the signs. Also, affected animals are extremely stressed and may be dangerous to work with, therefore exercise caution so no human injury results.

SAFETY IN PREPARED FEEDS: Cyanide is lost to the air with time, so processed feeds containing cherry may technically be free of the toxin. However, green chop and silage containing cherry will still retain large amounts of cyanide aside from being feeds of poor quality. Dried products would also not be of high quality if they contain cherry, but the cyanide levels will be much lower. Caution is still advised when feeding cherry-contaminated feeds.

PREVENTION: Do not allow animals to have access to damaged cherry leaves, especially if they are hungry and there is no other forage available. Do not place fallen branches or tree trimmings where animals can graze them. Exercise caution with animals on pasture after storms, during droughts or after a frost since these conditions will increase the chances of toxic levels of ingestion. For pets, do not house or confine animals in the vicinity of cherry, since boredom will increase the likelihood that the plant will be eaten. For most species of cherry, the fruit is safe for consumption. It is the leaves and bark which pose the greatest risk.