Page 1004 - Veterinary Toxicology, Basic and Clinical Principles, 3rd Edition

936 SECTION | XIV Poisonous Plants

VetBooks.ir CLINICAL DISEASE TABLE 64.2 Common Plants Sources and Reported
Clinical manifestation of cyanide poisoning may be acute
Cyanide Levels
or chronic depending on the amount of glycoside in the
plant, the amount and rate of ingestion, and the animal Plant Source HCN (mg/100 g Plant)
species involved. Acute poisoning occurs when hydrogen Sorghum
cyanide (HCN 5 prussic acid) is liberated from the glyco-
Seeds ,10
side through enzymatic interactions and the detoxification
mechanism in the animal is overwhelmed (Cheeke and Young plant tips 240
Shull, 1985). There are major animal species difference in Green leaves 60
ability to utilize plants containing cyanogenic glycosides
Arrow grass 77
(Ballhorn, 2011; Ballhorn et al., 2016). For example,
Almonds a
ruminants are generally more susceptible than nonrumi-
nants because the rumen pH is more neutral in supporting Bitter seeds 290
the glucosidases and lyases required to liberate the HCN Young leaves 20
from the glycoside, and these enzymes are readily avail-
Choke cherry 140 370
able in the rumen soup due to microbial activity (Majak
et al., 1990). Poisoning in sheep, cattle, goats, and wild Peach
ruminants have all been reported (Gibb et al., 1974; Pits 160
Burrows and Way, 1979; Burrows, 1981; Quinton, 1985;
Leaves 125
Knight and Walter, 2001; Soto-Blanco et al., 2008).
Conversely, simple stomached animals such as pigs, dogs, Bamboo
and humans with relatively high acidic pH in the stomach Stems 300
have a reduced rate of glycoside hydrolysis and acute cya- New shoots 800
nide poisoning from plant origin is less common
Cassava
(Ballantyne, 1983). Horses have a large cecum to digest
plant material but respond similar to simple stomached Leaves 100 200
animals when compared to ruminants. Most plant-induced Bitter tubers 80 400
cyanide poisoning in people is chronic and associated
Sweet tubers ,50
with consumption of high starch diets consisting of cas-
sava tubers. If the plant material containing cyanogenic Linseed meal 53
glycosides is eaten in toxic amounts or over a prolonged Service berry 200 400
period of time multiple disease conditions may be mani- Lima beans b
fest from acute toxicoses and rapid death to a more pro-
Black beans 300 400
tracted chronic neurological disease.
An interesting example of co-evolutionary adaptation Colored beans 17 312
to cyanide-containing plants is the giant panda bear, bam- White beans 10 210
boo lemurs of Madagascar, and mountain gorillas of
a Fifty bitter almonds may be lethal in adults or 5 10 in children
Rwanda (Ballhorn et al., 2016). Bamboo is a grass and
(Chaouali et al., 2013).
the new growth bamboo shoots contain the highest levels b Levels of HCN varied depending on which country reporting.
Source: Adapted from multiple sources: Montgomery, R.D., 1965. The
of cyanogenic glycosides of any plant species
medical significance of cyanogen in plant foodstuffs. Am. J. Clin. Nutr.
(Table 64.2). While the panda lives almost exclusively on 17, 103 113 (Montgomery, 1965); Montgomery, R.D., 1980.
bamboo, consuming large quantities of leaves, stems, and Cyanogens. In: Liener, I.E. (Ed.), Toxic Constituents of Plant Foodstuffs.
Academic Press, New York, NY, pp. 143 160 (Montgomery, 1980);
shoots (up to 25% of their body weight daily), the lemurs Baumeister, R.G.H., Schievelbein, H., Zickgraf-Rudel, G., 1975.
Toxicological and clinical aspects of cyanide metabolism. Drug Res. 25,
and gorillas forage on bamboo during certain times of the
1056 1064 (Baumeister et al., 1975); Kingsbury, J.M., 1964. Poisonous
year when the shoots are succulent and tender. Plants of the United States and Canada. Prentice Hall, Englewood Cliffs,
NJ, pp. 23 26 (Kingsbury, 1964); Cheeke, P.R., Shull, L.R., 1985.
Interestingly, this is when the bamboo contains the high-
Natural Toxicants in Feeds and Poisonous Plants. AVI Publishing,
est levels of cyanide. Thus, the panda, lemurs, and Westport, CN, pp. 173 234 (Cheeke and Shull, 1985).
gorillas have a unique ability to utilize this high CN-
containing forage without any acute or chronic deleterious
ability to utilize this high CN-containing forage is being
effects (Ballhorn et al., 2016). Lemurs and gorillas only
studied but is yet unknown (Ballhorn et al., 2016).
eat the bamboo at certain times and only as a part of their
Obviously the panda’s evolutionary niche involves some
diet whereas the panda subsists almost exclusively on metabolic advantage to utilize this plant as a major nutri-
bamboo. The mechanism associated with the panda’s tional source. In a general statement, this evolutionary