Cyanides and their toxicity: A literature review

Summary

Cyanide is a potent and rapidly‐acting asphyxiant which prevents tissue utilization of oxygen by inhibition of the cellular respiratory enzyme, cytochrome oxidase. Inhalation or ingestion of cyanide produces reactions within a few seconds and death within minutes. Cyanide toxicity of dietary origin has been implicated in acute animal deaths and as major etiologic factors in toxic ataxic neuropathy in man and as a cause of vision failure in humans suffering from tobacco amblyopia and leber's hereditary optic atrophy. Diagnosis of cyanide toxicity may be confirmed by a variety of laboratory procedures, but accurate assay is essential for proper conclusions from analysis of animal tissues several hours after death or from human samples in instances of chronic dietary exposure. Biological detoxification of cyanide is available through several routes, and the application of sodium nitrite with sodium thiosulfate or administration of methylene blue are effective treatment procedure. The environmental availability of cyanide in its various forms necessitates an understanding of its pathophysiology and responsible management of hazardous situations.     

Sodium nitroprusside, a convenient source of dietary cyanide for the study of chronic cyanide toxicity

1. The suitability of sodium nitroprusside (SNP) as a source of dietary cyanide has been tested with growing chicks and with hens by measuring plasma or urinary thiocyanate; the major detoxication product of cyanide. 2. Growth and food intake were depressed and plasma thiocyanate concentration was increased in chicks in a progressive manner as the dietary concentration of SNP was increased from 0 to 0.5 g/kg. 3. In laying hens, urinary excretion of thiocyanate was increased fivefold by including SNP in the diet at 0.3 g/kg. 4. It is concluded that SNP is a suitable and convenient source of dietary cyanide for the investigation of chronic cyanide toxicity.     

Cyanide toxicosis in goats after ingestion of California Holly (Heteromeles arbutifolia).

Cyanogenic glycosides are found in many native and naturalized plants throughout North America. The glycosides themselves are not toxic, but they yield hydrogen cyanide (hydrocyanic or prussic acid) when they are hydrolyzed by beta-glycosidases, either as a result of injury to the plant cells or by microbial action in the rumen. Hydrogen cyanide is readily absorbed from the gastrointestinal tract. Cyanide ion binds with iron in cytochrome oxidase, interfering with cellular respiration. The clinical effects are peracute, often resulting in death less than 1 hour after ingestion. This study describes a case that resulted in significant morbidity and mortality in a herd of goats after exposure to California holly (Heteromeles arbutifolia).     

Milk transfer of cyanide and thiocyanate: Cyanide exposure by lactation in goats

The present work was aimed at evaluating the effects of maternal exposure to potassium cyanide (KCN) during lactation in goats. Twenty-seven lactating female goats were orally dosed with 0 (control), 1.0, 2.0, or 3.0 mg KCN/kg body weight/day from lactation days 0 to 90. After this period, all male kids and one mother from each group were killed for a pathological study. Cyanide treatment promoted the clinical signs of maternal toxicity in the highest KCN group but did not affect body weight. Both cyanide and thiocyanate presented increased levels in both dams and kids from the treated groups. Microscopic lesions, but without alterations on the biochemical panel, were found in the brain, thyroid, liver, and kidneys of both dams and kids from the treated groups. These findings suggest that lactating offspring can be indirectly intoxicated by maternal exposure to cyanide.     

木薯及其副产品的营养价值及在动物生产中的应用

木薯耐干旱、耐贫瘠且易管理，其茎叶、块根及工业副产物营养物质含量较高，是一种优质的非常规饲料。木薯叶粗蛋白质、粗脂肪、灰分含量较高，含有丰富的钙、铁、锌、锰。木薯块根是很好的能量来源，其粗蛋白质、粗脂肪、矿物质、维生素含量低于木薯叶。木薯渣主要由木薯的外皮、破碎细胞壁等组成，粗蛋白质含量很低，粗纤维、中性洗涤纤维、酸性洗涤纤维含量较高，矿物质、氨基酸丰富，但钙、磷、氨基酸不平衡。木薯品种、生长条件、收割方式、收获时间、加工工艺等均会影响木薯及其副产品营养物质的含量。木薯中含有氰化物、单宁及植酸等抗营养因子，其中氰化物是限制木薯应用的最主要因素，其可结合细胞色素C氧化酶，阻断线粒体电子传递链，抑制有氧呼吸，导致中枢神经系统抑制和死亡。单宁、植酸与蛋白质结合生成络合物，阻碍营养物质的消化吸收，可通过水煮、烘烤、干燥等物理化学方法，以及发酵、育种等手段对木薯进行脱毒。研究表明，木薯及其副产品可广泛应用于动物生产中，对动物生长性能、肉品质无不良影响。开发与利用非常规饲料有利于缓解饲料资源紧张，降低养殖成本。作者详细介绍了木薯及其副产品的营养价值、抗营养因子及其脱毒方法以及其在动物生产上的应用，以期为木薯在畜禽养殖中的综合利用提供一定的参考。     

Effect of potassium cyanide on behaviour and time to death in possums

AIM: To assess the sickness behaviours of possums after eating a lethal dose of potassium cyanide. METHOD: Spontaneous behaviour and the time to loss of physical responses were examined. RESULTS: Cyanide ingestion caused a short-lasting period of mild respiratory stimulation. There was no salivation, retching or vomiting. Convulsions occurred in 73% of the possums. After the ingestion of cyanide, the average time to onset of ataxia was 3 minutes, the average time to overall loss of consciousness was 6.5 minutes, and the time to cessation of breathing was 18 minutes. CONCLUSION: Cyanide is a rapid-acting toxin with few undesirable signs from the welfare perspective.     

The acute toxicity of four common poisons to the opossum,Trichosurus vulpecula

Extract

Although a number of poisons are used for the destruction of opossums, Trichosurus vulpecula (Kerr), very little information on their acute toxic effects is available. A study of the toxicity of four poisons was therefore undertaken. Two of these compounds, sodium monofluoroacetate and sodium cyanide, are used as toxins against opossums in New Zealand, and two others, arsenic trioxide and strychnine, alkaloid, are used for the destruction of rabbits. Arsenic trioxide and strychnine were suggested as replacements for sodium monofluoroacetate and sodium cyanide by the Rabbit Destruction Council (pers. comm.). They suggested strychnine as a substitute for cyanide to overcome poison shyness and arsenic as a substitute for sodium monofluoroacetate to circumvent the danger of secondary poisoning to farmers' dogs.     

Effect of dietary sodium nitroprusside as a source of cyanide on the selenium status of chicks given diets of varying selenium concentration

1. The interaction between dietary cyanide, given in the form of sodium nitroprusside (SNP), and selenium has been studied in two experiments with growing chicks from 14 to 38 d of age.

2. In experiment 1, dietary selenium at 10 mg Se/kg reduced growth, food intake and efficiency of utilisation, and increased relative liver size and selenium content. All of these effects were eliminated by the addition of 0–1 g SNP/kg except for liver selenium content, which progressively declined towards control values as SNP was increased to 0–4 g/kg in increments of 0.1 g/kg. At 0.3 g SNP/kg, cyanide toxicity, as judged by decreased growth, reached significance.

3. In experiment 2, similar effects were observed with selenium at 10 mg Se/kg and SNP at 0.3 g/kg, but selenium deficiency was not evident from growth indicators when selenium supplementation of the diet was omitted completely, nor did these indicators suggest that deficiency was induced by cyanide.

4. In both experiments, plasma and liver glutathione peroxidase activity reflected the dietary selenium content. There was an interaction with dietary SNP content. With selenium intake at a toxic level, SNP increased enzyme activity, further evidence of alleviation of selenium toxicity, but when selenium intake was low and normal, SNP decreased activity in liver, an indication that cyanide could induce deficiency.

5. A possible mechanism for alleviation of selenium toxicity is proposed.     

Reduced selenium status in chicks given diets low in sulphur-containing amino acids and containing sodium nitroprusside as a source of cyanide

1. Two experiments were carried out to study the effect of dietary cyanide, given in the form of sodium nitroprusside (SNP), on the growth and selenium status of chicks fed on diets low in sulphur-containing amino acids. 2. In experiment 1, SNP (0.3 g/kg) depressed growth rate and food intake when included in diets low in total sulphur-containing amino acids. It also reduced plasma and liver glutathione peroxidase activity (GSH-Px) and kidney selenium concentration. These latter variables also showed increases in response to supplements of selenium of 0.1 and 0.2 mg selenium/kg (as sodium selenite) although growth was not affected. 3. In experiment 2, SNP did not affect growth when reduced to 0.1 g/kg in diets low both in methionine and total sulphur-containing amino acids. It did, however, reduce plasma GSH-Px activity, which again increased in response to similar dietary supplements of selenium. 4. It is concluded that dietary cyanide effectively increases the requirement for selenium and could induce deficiency in diets only marginally adequate in selenium, particularly when the supply of sulphur-containing amino acids was marginal or inadequate.     

饲料中的霉菌毒素及其防制措施

霉菌毒素是由真菌或霉菌产生的次级代谢产物,在动物体中,霉菌毒素的毒性是慢性的,很少引起动物死亡。但是霉菌毒素的存在降低了饲料的营养价值,以及动物的生产性能,从而影响生产力,且霉菌毒素在畜产品(肉、奶等)中的残留会给人类健康带来严重威胁。作者主要介绍了饲料中常见的霉菌毒素(黄曲霉毒素、赭曲霉毒素、玉米赤霉烯酮、脱氧雪腐镰刀菌烯醇、T-2毒素、伏马菌素等),以及其毒性和危害,并从预防与去毒两个方面,阐述了霉菌毒素的防制措施,进而减少霉菌毒素造成的危害。     

纳米硒在动物营养中的研究进展

硒(Se)是动物机体必需的微量元素,在机体抗氧化体系、免疫细胞功能、促生长及精子的形成和游动、前列腺素的功能等方面起着重要作用。动物体内已知存在35种以上的含硒蛋白质,其中谷胱甘肽过氧化物酶(GPx1-GPx6)和硫氧还蛋白还原酶(TrxR1-TrxR3)在机体抗氧化体系中发挥着重要的作用。国内生产中通常应用亚硒酸钠作为补硒制剂,但亚硒酸钠在使用中存在吸收率低、过氧化作用及潜在的污染等问题。有机硒和纳米硒具有吸收率高、生物活性强、环境污染小等优点。与有机硒相比,纳米硒有更显著的低毒高效性,是已发现的毒性最低的补硒制剂。近年来,纳米硒替代有机硒、无机硒源的研究已成为热点。     

Cyanide toxicosis in Asian small-clawed otters (Amblonyx cinereus) secondary to ingestion of loquat (Eriobotrya japonica).

Two Asian small-clawed otters (Amblonyx cinereus) died acutely in their exhibit within a 4-day period. Neither animal had significant gross lesions at necropsy. Histologic findings were consistent with acute vascular shock and disseminated intravascular coagulation, and a toxic etiology was suspected. The animals' exhibit contained opened, uneaten loquat (Eriobotrya japonica) fruit with the seeds removed and large quantities of undigested loquat seed material in the feces of the remaining animals. Cyanide was detected in the stomach contents collected at necropsy and in fresh loquat seeds from the exhibit. Loquat is related to other cyanide-containing fruit trees, including cherries, peaches, and almonds.     

Apoptosis in the mammalian CNS: Lessons from animal models

It is generally assumed that about half of the neurons produced during neurogenesis die before completion of maturation of the central nervous system (CNS). Neural cell death is also relevant in aging and several neurodegenerative diseases. Among the modalities by which neurons die, apoptosis has very much attracted the interest of investigators because in this type of cell death neurons are actively responsible for their own demise by switching on a number of genes and activating a series of specific intracellular pathways. This review focuses on the cellular and molecular mechanisms of apoptosis in normal and transgenic animal models related to naturally occurring neuronal death within the CNS. We will also consider some examples of apoptotic cell death in canine neuropathologies. A thorough analysis of naturally occurring neuronal death in vivo will offer a basis for parallel and future studies involving secondary neuronal loss such as those in neurodegenerative disorders, trauma or ischaemia.     

The Influences of Dietary Intakes and Supplementation with Selenium and Vitamin E on Reproduction Diseases and Reproductive Efficiency in Cattle and Sheep

Retained placenta, endometritis, cystic ovaries and low conception rates are often considered as interconnected conditions in cattle. Wide ranges in amounts of selenium and vitamin E supplements have been advised in late-pregnancy diets and, frequently, they can be synergistically beneficial. Animals at grass or with other green foods should be of adequate vitamin E status, but dietary selenium deficiencies are both more frequent and severe. Selenium status is important for superovulation in cattle and multiple births in ewes because of its importance in sperm transport and establishment of ova. However, the potential toxicity of selenium-enriched feed supplements restricts their use on a free-access basis. Giving sodium selenite or selenate by injection provides only a short-term response in the plasma. Barium selenate given in oil by injection provides a more durable response but has potential tissue residue problems. Compressed metallic selenium powder with iron powder in high-density reticulo-ruminal pellets gives sustained release, but uncertainties regarding possible surface coating and the variable effects of selenium particle size may require additional grinders to ensure prolonged release. Neither reticulo-ruminal pellets of such composition nor barium selenate by injection may be used worldwide because only sodium selenite and selenate have general regulatory approval. A sustained-release multi-trace element/vitamin rumen bolus system effective for several months has increased lambing percentages in ewes, and increased herd conception rates and reduced the spread of calving for herds of beef cattle.     

Acute and long-term effects of exposure to sodium monofluoroacetate (1080) in sheep

Acute and long-term effects of a single, relatively high oral dose (0.25 and 0.30 mg/kg) of sodium monofluoroacetate (1080) on the survival and productivity of sheep were evaluated to establish a better understanding of 1080 poisoning and identify more specific changes diagnostic of toxicosis. In survivors, clinical signs of acute 1080 toxicosis such as salivation and lethargy were generally very mild. Fasted animals were more prone to 1080 toxicity. In animals that died, more severe signs, including tachypnoea, dyspnoea, and tremors occurred for 15-20 min prior to death. 1080 concentrations were highest in the blood > heart > skeletal muscle > liver. 1080 could not be detected in any of these organs of the animals that survived. Serum citrate concentrations were elevated for 4 days after dosing. No clinical or biochemical abnormalities were found in any animal after 4 days. Histopathological lesions were most marked in the heart and lung with inflammation, necrosis, and scattered foci of fibrous tissue in the myocardium, pulmonary oedema and inflammation of the lung. No adverse long-term effects on general health or reproductive performance were observed in any sheep that survived the first 4 days following exposure to 1080. The most reliable diagnostic indicators of 1080 exposure in sheep were measurement of its residues in blood, skeletal muscle and ruminal contents, increased serum citrate concentration, elevated heart rate, and characteristic electrocardiograph changes (up to 4 days after exposure). Death from 1080 is most likely to occur within 96 h, and animals that survived this period appeared normal.     

Poisoning with 3-nitropropionic acid in possums (Trichosurus vulpecula)

AIMS: To evaluate the toxicity, animal behavioural effects and animal welfare implications of 3-nitropropionic acid administration in possums. METHODS: The behavioural effects following 3-nitropropionic acid administration were recorded in 26 possums. RESULTS: The oral LD50 was between 110 and 170 mg/kg. Time to death averaged 9.5+/-1.9 h (mean+/-s.e.m.). Adverse signs from an animal welfare perspective were retching and restless behaviour that occurred in episodes during a period that averaged 1 h 51 min. Retching occurred in possums that were injected intraperitoneally or dosed orally with the 3-nitropropionic acid, suggesting that this effect was not necessarily initiated by gastric irritation. CONCLUSION: The potency of 3-nitropropionic acid as a toxin was low compared to other toxins that are used in possums, but it is relatively quick acting. It may cause some discomfort (retching and restlessness) prior to death.     

饲草料中的天然有毒有害物质及其对羊的危害

抗营养因子广泛存在于植物界,这些有毒有害物质进入动物体内后,其可能转化为具有更大活性和毒性的物质,引起畜禽产品质量和产量下降,起到致病作用,甚至引起死亡。主要对饲草料中硝酸盐及亚硝酸盐、苷类物质、棉酚等抗营养因子的危害作一介绍。     

Cyanide intoxication in sheep: enhancement of efficacy of sodium nitrite, sodium thiosulfate, and cobaltous chloride.

For treatment of cyanide intoxication of ruminants, the present recommended doses of sodium nitrite (5 mg/kg of body weight) and sodium thiosulfate (25 to 50 mg/kg) are smaller than those recommended for other animals; the decrease is partially attributed to the greater susceptibility of ruminants to the toxic effects of sodium nitrite. Based on the high tissue concentration and activity rate of rhodanese in ruminants, sulfur donors such as sodium thiosulfate could be utilized more efficaciously. Doses of sodium nitrite and sodium thiosulfate (up to 22 and 660 mg/kg, respectively) were evaluated in the present studies. Adjustment of the antidotal combination provided almost three times the protection afforded by the previously recommended doses. Moreover, under the conditions tested, the newly adjusted dose levels of sodium thiosulfate alone were more effective than the previously used antidotal combination of sodium nitrite and sodium thiosulfate and this protective effect was enhanced by cobaltous chloride (10.6 mg/kg) or sodium nitrite. The present recommended therapeutic approach to cyanide intoxication in sheep should be based primarily on administration of a much higher dose of sodium thiosulfate in combination with sodium nitrite or cobaltous chloride (or both).     

酵母硒在动物生产中的研究与应用

硒(selenium)是人和动物必需的微量元素,它与调节生长、提高机体免疫力、抗癌、抗氧化、抗应激、延缓衰老及防治地方病等有着密切的关系。国内的补硒方法是添加亚硒酸钠,但亚硒酸钠毒性大,吸收转化率低及造成环境污染。近年来,人们逐渐把目光转向毒性小且生物利用率高的有机硒上,其中酵母硒成为研究与应用的热点。     

Pet food safety: sodium in pet foods

Healthy dogs and cats appear to be able to adjust to differing amounts of sodium in their diet via the rennin-angiotensin-aldosterone mechanisms. There is no strong evidence that increased dietary sodium increases the risk of hypertension in dogs and cats, and the current recommendation for hypertensive animals is to avoid high dietary salt intake without making a specific effort to restrict it. The prevalence of salt sensitivity and its effect on blood pressure has not been determined for cats or dogs. The ideal amount of sodium in the diet of dogs and cats with cardiac deficiency has not been determined, as increasing may detrimentally increase the extracellular fluid volume, but decreasing it may detrimentally increase the activation of the rennin-angiotensin-aldosterone system. Increased dietary sodium increases urine output and may decrease the risk of forming calcium oxalate uroliths due to the decrease in relative supersaturation of solutes. However, caution should be used in increasing the sodium intake of patients with renal disease as increased dietary sodium may have a negative effect on the kidneys independent of any effect on blood pressure.