Poisoning of sheep by seeds of Crotalaria retusa: Acquired resistance by continuous administration of low doses

Plants causing poisoning outbreaks of livestock in South America: A review

This paper reviews toxic plants for livestock in South America. We included 219 plants in this review, considering only the plants that caused at least one demonstrated outbreak of poisoning. Plants reported as toxic in other regions and present in South America, but with no confirmed outbreaks of poisoning in this region, are not included. We report the main aspects of the epidemiology, clinical signs, pathology and economical importance of the poisonings. Initially, the toxic plants are described based on their toxic compounds, but because the toxic compound is unknown in 92 (42%) of the plants we also classify them according to the affected system. This review highlights the great diversity of toxic plants capable of affecting livestock in South America, and for this reason studies in this regard should be intensified.

Metabolism-mediated cytotoxicity and genotoxicity of pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PAs) and PA N-oxides are common phytotoxins produced by over 6000 plant species. Humans are frequently exposed to PAs via ingestion of PA-containing herbal products or PA-contaminated foods. PAs require metabolic activation to form pyrrole-protein adducts and pyrrole-DNA adducts which lead to cytotoxicity and genotoxicity. Individual PAs differ in their metabolic activation patterns, which may cause significant difference in toxic potency of different PAs. This review discusses the current knowledge and recent advances of metabolic pathways of different PAs, especially the metabolic activation and metabolism-mediated cytotoxicity and genotoxicity, and the risk evaluation methods of PA exposure. In addition, this review provides perspectives of precision toxicity assessment strategies and biomarker development for the risk control and translational investigations of human intoxication by PAs.

Toxic Wasting Disorders in Sheep

Simple Summary

There are several substances, either inorganic or organic that may be toxic for sheep. Intoxications by some of these substances have an acute clinical course with specific signs and lesions that may guide the diagnostic procedures. However, there are other insidious, subacute to chronic presentations, usually related to continuous intake of the toxic substance over long periods of time, that may present with emaciation, ill-thrift, and/or poor external aspect. In such scenarios, diagnosis may be challenging and should be achieved through a combination of history of exposure, subtle gross and histological findings (if present), and available ancillary tests.

Abstract

Infectious and parasitic agents have been frequently associated with debilitating and wasting conditions in sheep. The prevalence of these agents has probably undermined the role of toxic causes as contributors to such disorders. In addition, many of these intoxications frequently produce acute clinical disease with specific and characteristic lesions, thus a causal relationship with the toxic substance may be relatively easy to establish. However, persistent exposure to some of these organic or inorganic toxic substances may lead to emaciation, ill-thrift, and poor external aspect. The anti-nutritional factors and alkaloids of several plants, including pyrrolizidine alkaloids, among others, have also been associated with emaciation and/or poor general performance in sheep flocks. In this review, some of these disorders are discussed with an emphasis on clinical signs and lesions, relevant diagnostic aspects, and available therapeutic approaches. In most cases, demonstrating a history of exposure should be one of the most relevant aspects of the diagnostic approach, and removing the animals from the toxic source is the cornerstone of the majority of the treatment strategies.

Screening of food supplements for toxic pyrrolizidine alkaloids

Pyrrolizidine alkaloids (PA) and PA-N-oxides (PANO) are a group of more than 660 secondary plant metabolites with hepatotoxic, carcinogenic and mutagenic effects in animals and humans. The phytotoxins can enter the food chain by transfer of PA/PANO between plants via the soil, unintended co-harvesting of PA/PANO-producing weeds, as well as by honeybees collecting pollen and nectar of these plants. Thus, bee- and plant-based products, e.g. (herbal) teas, spices and culinary herbs were identified to be a main source of consumers’ exposure to PA/PANO. Consequently, food supplements based on those ingredients may as well be contaminated with PA/PANO, but so far there are only very few studies available on this topic. Therefore, the current study investigated 50 herbal and bee product-based food supplements available in German retail pharmacies, drugstores, and online on the occurrence of 44 PA/PANO. In total, 19 samples contained PA/PANO with sum contents ranging from 0.1 to 105.1 ng/g in solid samples and from 0.03 to 2.20 ng/mL in liquid preparations. Considering the recommended daily consumption, the sum contents were of no or little concern for the health risk of adults, whereas in case of children the contents of singular samples could significantly contribute to the overall PA/PANO exposure.

In vitro metabolism of pyrrolizidine alkaloids - Metabolic degradation and GSH conjugate formation of different structure types

Pyrrolizidine alkaloid (PA) forming plants are found worldwide and may contaminate food products at levels being of concern for human health. Due to the high biodiversity of PA producing plants many different types of PA structures are formed. PAs themselves are not toxic but require metabolic activation to exert toxicity. To investigate if the structure of the PAs affects their in vitro metabolism, we incubated a set of 22 PAs and compared the degradation rates and the amount of formed glutathione (GSH) conjugates. With human liver microsomes, no metabolic degradation of monoesters was found. Degradation rates of diester PAs tended to correlate with their hydrophilicity, whereby the more polar and branched-chained PAs exhibited lower degradation. There was a trend towards higher degradation rates in the presence of rat liver microsomes, but the GSH conjugate levels were similar. Although an effective degradation seems to be related with high GSH conjugate levels, no clear correlation between both parameters could be deduced. For both species no GSH conjugates, or only trace amounts, were formed from monoesters. However, for both open-chained as well as cyclic diesters GSH conjugates were detected and determined levels were comparable for both ester types without major structure-dependent differences.

Development of a sensitive analytical method for determining 44 pyrrolizidine alkaloids in teas and herbal teas via LC-ESI-MS/MS

Pyrrolizidine alkaloids (PA) and PA-N-oxides (PANO) are a large group of secondary plant metabolites comprising more than 660 compounds. Exhibiting geno- and hepatotoxic properties, they are responsible for multiple cases of food and feed poisoning over the last 100 years. For food and feed safety reasons, relevant PA/PANO should be monitored extensively in the main sources of PA/PANO intake. In this study, a sensitive analytical method was developed for detecting a broad range of 44 commercially available PA/PANO compounds, and in-house validation procedures were performed for several (herbal) teas. Various extraction solvents and procedures, as well as solid phase extraction materials for sample clean-up and analyte concentration, were tested to establish the methods' efficiency and effectiveness. Chromatographic conditions were optimised to obtain the best possible separation of isomers for the 44 PA/PANO analytes. The final method was proven very sensitive and accurate, with detection limits ranging from 0.1 to 7.0 μg/kg and precisions between 0.7 and 16.1%. For 40 of the analytes, the recovery rates ranged from 60.7 to 128.8%. The applicability and trueness of the method were examined by analysing tea samples from a local supermarket and comparing them to a reference material. At least one PA/PANO analyte was detected in 17 of the 18 samples under investigation, and the sum contents of the samples ranged from 0.1 to 47.9 μg/kg. Knowledge of the PA/PANO composition in a sample can be used to indicate the botanical origin of the impurity and, thus, the geographical region of cultivation.

Economic impact of an outbreak of botulism in a cattle feedlot

ABSTRACT: Botulism is a febrile disease, fatal in most cases, which affects the muscles of locomotion, chewing, and swallowing, as well as the diaphragm and intercostal muscles, causing flaccid paralysis and respiratory arrest. In bovines, the etiology is due to the ingestion of neurotoxins types C and D formed by the bacterium Clostridium botulinum in an animal or vegetal substance, during decomposition. Vaccination is one of the most effective prophylactic means to prevent this disease. In this study, an outbreak of botulism was evaluated in a feedlot with 6,300 finishing cattle, wherein 25 died as a consequence of contracting this disease. The economic losses resulting from the deaths were analyzed, and economic analysis was conducted, involving the estimated cost of vaccination for the whole herd under risk, with the objective of evaluating whether this prophylactic practice is a viable action plan. The financial loss due to the deaths resulting from botulism in the case studied was found to be R$55,560.00, equivalent to 0.39% of the total monetary value of the herd. The cost of immunizing the entire herd under risk was 14.06% (for toxins exclusive to toxins C and D) and 22.22% (for polyvalent vaccines against clostridiosis) of the financial loss incurred as a consequence of the recorded deaths. It was concluded that botulism is a disease that can cause a significant economic impact on intensive livestock production systems, and that vaccination is an economically viable prophylactic action if performed with adequate sanitary planning.

Influence of Storage on the Stability of Toxic Pyrrolizidine Alkaloids and Their N-Oxides in Peppermint Tea, Hay, and Honey

1,2-Dehydropyrrolizidine alkaloids (PA) and PA- N-oxides (PANO) are phytotoxins, which presumably occur in more than 6,000 plant species worldwide. Plants containing PA/PANO are responsible for various food and feed poisonings recorded for decades. Main reasons of exposition of consumers and livestock are contaminations of food and animal feed with parts, seeds, pollen, or nectar of PA-containing plants. Concerning stability, effects of processing on PA were mainly investigated in the past. The current study examined the behavior of PA/PANO in unprocessed matrices peppermint tea, hay, and honey during storage. Blank samples were fortified with PA/PANO or contaminated with blueweed ( Echium vulgare) and ragwort ( Senecio jacobaea) and stored for 182 d. The time-series analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmed that all 25 analyzed PA/PANO compounds remained stable in herbal samples. However, the results showed a very fast decrease of PANO in honey samples within hours. These results were discussed with respect to potential consequences for health risk assessment.

Aspectos epidemiológicos, clínico-patológicos e diagnóstico precoce da seneciose bovina no Oeste do Rio Grande do Sul

RESUMO: A ingestão de Senecio spp. (maria-mole) é, possivelmente, a principal causa de morte de bovinos por agentes tóxicos nas regiões central e sul do Rio Grande do Sul. Ao considerar a limitação de informações acerca dessa condição no Oeste do Rio Grande do Sul, esse trabalho objetiva descrever os principais aspectos epidemiológicos e clínico-patológicos da seneciose em bovinos nessa região. O estudo foi realizado por meio da aplicação de questionários em 16 propriedades rurais de municípios da região que apresentaram casos suspeitos da intoxicação em bovinos, de agosto de 2011 a março de 2014. Durante as visitas as propriedades foram coletadas plantas do gênero Senecio para identificação botânica, bem como se procedeu a coleta de fragmentos de fígado através de biópsia transtorácica para confirmação da intoxicação. As espécies de Senecio mais frequentes nas propriedades foram S. brasiliensis e S. heterotrichius. De um total de 88 bovinos, de nove propriedades distintas, que apresentaram falha no ganho de peso, 69 animais (aproximadamente 80%) foram positivos para seneciose crônica por apresentarem lesões características da intoxicação, tais como fibrose periportal (78% dos casos), megalocitose (76% dos casos) e proliferação de ductos biliares (68% dos casos), classificadas entre discretas e acentuadas. O trabalho confirmou a ocorrência da doença, mesmo em bovinos sem sinais clínicos evidentes. Os resultados obtidos nessas avaliações foram fundamentais para orientar proprietários e técnicos quanto às principais características da doença e às formas de controle a serem adotadas. O emprego da biópsia hepática possibilitou o diagnóstico precoce da intoxicação e auxiliou os criadores quanto ao descarte mais criterioso de bovinos e a real situação da intoxicação no rebanho, minimizando as perdas econômicas.

In vitro biotransformation of pyrrolizidine alkaloids in different species. Part I: Microsomal degradation

Pyrrolizidine alkaloids (PA) are secondary metabolites of certain flowering plants. The ingestion of PAs may result in acute and chronic effects in man and livestock with hepatotoxicity, mutagenicity, and carcinogenicity being identified as predominant effects. Several hundred PAs sharing the diol pyrrolizidine as a core structure are formed by plants. Although many congeners may cause adverse effects, differences in the toxic potency have been detected in animal tests. It is generally accepted that PAs themselves are biologically and toxicologically inactive and require metabolic activation. Consequently, a strong relationship between activating metabolism and toxicity can be expected. Concerning PA susceptibility, marked differences between species were reported with a comparatively high susceptibility in horses, while goat and sheep seem to be almost resistant. Therefore, we investigated the in vitro degradation rate of four frequently occurring PAs by liver enzymes present in S9 fractions from human, pig, cow, horse, rat, rabbit, goat, and sheep liver. Unexpectedly, almost no metabolic degradation of any PA was observed for susceptible species such as human, pig, horse, or cow. If the formation of toxic metabolites represents a crucial bioactivation step, the found inverse conversion rates of PAs compared to the known susceptibility require further investigation.

UPLC-MS/MS method for determination of selected pyrrolizidine alkaloids in feed

Alkaloids known as secondary metabolites are grouped by typical structural characteristics into large families such as pyrrolizidine alkaloids (PAs) comprising more than 350 individual heterocyclic compounds. The PAs present a serious health risk to human and livestock; hence there is a need for methods that allow these dangerous plant toxins to be determined. In this study, a fast, reliable and sensitive approach is proposed to identify and quantify PAs in feed samples. PAs including monocrotaline, senkirkine, senecionine, seneciphylline and retrorsine were determined by ultra-performance liquid chromatography coupled with tandem mass spectrometry. Sample preparation was based on a modified QuEChERS approach. The mean recovery, precision, matrix effects and limits of quantification were assessed for three matrices within the method validation. The presented method was used to inspect 41 various feed samples, where the presence of PAs was expected. Roughages and feed for rabbits contained the highest levels of PAs, in general.

Nobre VM, Dantas AFM, Colegate SM, Riet-Correa F. Natural and experimental poisoning of goats with the pyrrolizidine alkaloid–producing plant Crotalaria retusa L

Crotalaria retusa L. (rattleweed), estimated to contain about 4.96% monocrotaline (MCT) in the seed, was associated with a natural poisoning outbreak in goats. The poisoning was experimentally reproduced by the administration of C. retusa seeds containing approximately 4.49% of MCT. Thus, 1 of 3 goats given a single dose of 5 g/kg bodyweight (bw) of seeds (248 mg MCT/kg bw) and 2 goats given a single dose of 347 mg MCT/kg bw showed acute clinical signs and were euthanized 10–11 days after dosing. Clinical signs and gross and histologic lesions were characteristic of acute centrilobular liver necrosis.

Importância econômica, epidemiologia e controle das intoxicações por plantas no Brasil

A importância econômica, epidemiologia e controle das intoxicações por plantas em animais domésticos no Brasil são revisadas. Com os dados dos laboratórios de diagnóstico de diferentes regiões do país, as perdas anuais por mortes de animais foram estimadas em 820.761 a 1.755.763 bovinos, 399.800 a 445.309 ovinos, 52.675 a 63.292 caprinos e 38.559 equinos. No Brasil, atualmente, o número de plantas tóxicas é de 131 espécies e 79 gêneros e aumenta permanentemente. No entanto, a maioria das perdas são causadas por poucas plantas, incluindo Palicourea marcgravii, Amorimia spp., Senecio spp., Pteridium aquilinum, Ateleia glazioviana e Cestrum laevigatum em bovinos, Brachiaria spp em bovinos e ovinos, Nierembergia veitchii, Mimosa tenuiflora e Ipomoea asarifolia em ovinos, plantas que contêm swainsonina (Ipomoea carnea, Turbina cordata e Sida carpinifolia) em caprinos e Brachiaria humidicola e Crotalaria retusa em equinos. Os principais fatores epidemiológicos relacionados às intoxicações por plantas incluem palatabilidade, fome, sede, facilitação social, desconhecimento da planta, acesso a plantas tóxicas, dose tóxica, período de ingestão, variações de toxicidade e resistência/susceptibilidade dos animais às intoxicações. Quanto aos métodos de controle e profilaxia descrevem-se os resultados obtidos no Brasil com métodos recentemente desenvolvidos, incluindo controle biológico, aversão alimentar condicionada, utilização de variedades não tóxicas de forrageiras, utilização de animais resistentes às intoxicações e técnicas de indução de resistência.

Comparative potential therapeutic effect of sesame oil and peanut oil against acute monocrotaline (Crotalaria) poisoning in a rat model

BACKGROUND

Many Crotalaria plant species contain hepatotoxic pyrrolizidine alkaloids (such as monocrotaline) that can cause acute and chronic poisoning in cattle and other animals.

HYPOTHESIS

Peanut oil, atropine sulfate, and antidiarrheal agents are used to treat acute monocrotaline poisoning. The effect of sesame on acute monocrotaline poisoning has never been investigated.

ANIMALS

Fifty male Sprague-Dawley rats were used for toxicity studies.

METHODS

Experiment 1: Group I, control. Groups II-IV were given monocrotaline (205.2 mg/kg) and euthanized 6, 12, and 24 hours later. Experiment 2: Group I, control. Group II monocrotaline alone (205.2 mg/kg). Groups III-VI were given monocrotaline (205.2 mg/kg) and 1 hour later, Groups III and IV were given sesame oil (1 and 2 mL/kg) and Groups V and VI were given peanut oil (1 and 2 mL/kg).

RESULTS

Monocrotaline significantly decreased (P < .05) serum amylase activity, but, over time, increased (P < .05) pancreatic and lung injury. AST and ALT activity and liver injury peaked at 24 hours. Sesame oil and peanut oil (P < .05) inhibited the changes in all tested parameters in acute monocrotaline poisoning. Although peanut oil inhibited acute monocrotaline poisoning, it induced steatosis, but sesame oil did not.

CONCLUSION AND CLINICAL IMPORTANCE

We hypothesize that early pancreatic and lung injury and late liver injury contribute to acute monocrotaline poisoning and that sesame oil is more efficacious than peanut oil against acute monocrotaline poisoning in rats. However, additional studies are needed to confirm that these oils have the same effects in cattle and other animals.

Spontaneous acute poisoning by Crotalaria retusa in sheep and biological control of this plant with sheep

After the diagnosis of acute Crotalaria retusa poisoning, 21 healthy sheep from the affected flock were returned to the paddock and continued to consume the sprouting plants. Two years after returning these sheep to the paddock, very few plants were still alive, and after 3 years, no C. retusa plants were observed. The sheep had neither clinical signs nor biochemical alterations and delivered healthy lambs. It is concluded that resistant sheep can be used for the biological control of C. retusa.

Intoxicação aguda com sementes de Crotalaria spectabilis (Leg. Papilionoideae) em suínos

Relata-se necrose hepatocelular em suínos após consumo de ração que continha grãos de sorgo-granífero (Sorghum bicolor) acidentalmente contaminado com sementes de Crotalaria spectabilis. Morreram 76 suínos em quatro propriedades no município de Juscimeira, MT. Os sinais clínicos iniciaram-se 24-48 horas após o consumo da ração contaminada e foram caracterizados por depressão, letargia, apatia, inapetência, vômito, mucosas ictéricas ou pálidas, ascite, decúbito esternal, decúbito lateral com movimentos de pedalagem e convulsões, a evolução clínica foi de 48-60 horas seguida de morte. As Principais alterações macroscópicas foram fígado aumentado de tamanho com evidenciação do padrão lobular, ascite e hidrotórax com líquido de coloração amarelo avermelhado contendo filamentos com aspecto de fibrina, linfonodos aumentados e edema pulmonar interlobular. A doença foi reproduzida utilizando-se 16 suínos divididos em seis grupos que receberam sementes de C. spectabilis em diferentes doses. Necrose hepatocelular ocorreu em sete suínos, sendo dois que receberam doses diárias 2,5g/kg e cinco que receberam doses únicas de 5,0 e 9,5g/kg. Dez doses diárias de 0,5 e 1,25g/kg causaram fibrose hepática.

Seneciose crônica em ovinos no sul do Rio Grande do Sul

Descrevem-se dois surtos de intoxicação por Senecio spp. em ovinos a campo no sul do Rio Grande do Sul. A enfermidade ocorreu no ano 2006 em duas propriedades que estavam severamente invadidas pela planta e com acentuada escassez de forragem. A morbidade nos dois surtos variou de 10% a 9,5% nas duas propriedades, respectivamente. Na primeira propriedade os animais eram nascidos e criados na área e na outra os ovinos haviam sido adquiridos alguns meses antes do surto. Os sinais clínicos caracterizaram-se por emagrecimento progressivo, apatia, fraqueza, icterícia e fotossensibilização. Macroscopicamente, o fígado dos ovinos necropsiados estava aumentado de tamanho, amarelado, com superfície capsular irregular e vesícula biliar aumentada de tamanho e com edema da parede. Ao corte no fígado havia nódulos bem delimitados, esbranquiçados com 1-3mm de diâmetro. Havia, ainda, ascite e discreto edema de mesentério. Microscopicamente, as lesões hepáticas eram semelhantes em todos os fígados e caracterizadas por megalocitose, fibrose periportal, presença de hepatócitos tumefeitos, vacuolizados e de hepatócitos necróticos distribuídos aleatoriamente pelo parênquima hepático, hiperplasia das células dos ductos biliares e presença de pseudo-inclusões nos núcleos de hepatócitos. Encefalopatia hepática (status spongiosus) foi observada em todos os ovinos necropsiados. O diagnóstico foi baseado na epidemiologia, sinais clínicos, lesões macroscópicas e histológicas observadas. Concluiu-se que, apesar de a intoxicação por Senecio spp. ser pouco frequente em ovinos e essa espécie animal controlar eficientemente a planta, isso, aparentemente, depende da lotação utilizada e surtos da intoxicação podem ocorrer quando esta lotação é menor que 0,2 ovinos por hectare e há carência de forragem acentuada.

Intoxicação por alcaloides pirrolizidínicos em ruminantes e equinos no Brasil

Casos de intoxicação por alcaloides pirrolizidínicos (APs) em ruminantes e equinos foram investigados retrospectivamente através do acesso aos arquivos de dois laboratórios de diagnóstico veterinário no Sul e Nordeste brasileiro. Os dados obtidos foram comparados com aqueles retirados da literatura concernentes a surtos dessa toxicose no Brasil, onde ela é associada com a ingestão de plantas que contêm APs dos gêneros Senecio, Crotalaria e Echium. Formas aguda e crônica da toxicose foram encontradas. A doença aguda foi observada em associação com a ingestão de Crotalaria retusa em ovinos e caprinos. C. retusa e Senecio spp. também foram responsáveis pela intoxicação crônica em bovinos, equinos e ovinos. A intoxicação por APs é uma importante causa de morte em animais pecuários no Brasil. Essa é a principal causa de morte em bovinos na região Central do Rio Grande do Sul e uma das principais causas de morte em equinos na Paraíba. A epidemiologia, os sinais clínicos, a patologia e a importância da intoxicação por APs são descritos e discutidos.