Anticoagulant Rodenticides Research Articles

Toxicokinetic analysis of the anticoagulant rodenticides warfarin & diphacinone in Egyptian fruit bats (Rousettus aegyptiacus) as a comparative sensitivity assessment for Bonin fruit bats (Pteropus pselaphon)

Anticoagulant rodenticides have been widely used to eliminate wild rodents, which as invasive species on remote islands can disturb ecosystems. Since rodenticides can cause wildlife poisoning, it is necessary to evaluate the sensitivity of local mammals and birds to the poisons to ensure the rodenticides are used effectively. The Bonin Islands are an archipelago located 1000 km southeast of the Japanese mainland and are famous for the unique ecosystems. Here the first-generation anticoagulant rodenticide diphacinone has been used against introduced black rats (Rattus rattus). The only land mammal native to the archipelago is the Bonin fruit bat (Pteropus pselaphon), but little is known regarding its sensitivity to rodenticides. In this study, the Egyptian fruit bats (Rousettus aegyptiacus) was used as a model animal for in vivo pharmacokinetics and pharmacodynamics analysis and in vitro enzyme kinetics using their hepatic microsomal fractions. The structure of vitamin K epoxide reductase (VKORC1), the target protein of the rodenticide in the Bonin fruit bat, was predicted from its genome and its binding affinity to rodenticides was evaluated. The Egyptian fruit bats excreted diphacinone slowly and showed similar sensitivity to rats. In contrast, they excreted warfarin, another first-generation rodenticide, faster than rats and recovered from the toxic effect faster. An in silico binding study also indicated that the VKORC1 of fruit bats is relatively tolerant to warfarin, but binds strongly to diphacinone. These results suggest that even chemicals with the same mode of action display different sensitivities in different species: fruit bat species are relatively resistant to warfarin, but vulnerable to diphacinone.

Comments on “Conservation Letter: Raptors and Anticoagulant Rodenticides”

Comments on “Conservation Letter: Raptors and Anticoagulant Rodenticides”

VKORC1 single nucleotide polymorphisms in rodents in Spain

Rodents are considered one of the animal pests with the greatest impact on agricultural production and public health. Anticoagulant rodenticides (ARs), used as one of the most effective ways to control rodent populations worldwide, inhibit the vitamin K 2,3-epoxide reductase (VKORC1) enzyme involved in blood coagulation. Resistances to ARs are mainly associated with mutations or single nucleotide polymorphisms (SNPs) in the vkorc1 gene. Since the information on this subject is scarce in Spain, we monitored and discovered rodent SNPs that could favour genetic resistance in its populations. For that, more than 200 samples of stools and tails from brown rat (Rattus norvegicus), black rat (Rattus rattus) and mouse (Mus musculus) were collected from 12 Spanish regions previously identified with low AR efficacy in coordination with the National Association of Environmental Sanitation Companies (ANECPLA) and the managing entities of four locations. We then sequenced their vkorc1 exon 3 corresponding genomic DNA. We identified genotypic vkorc1 variations corresponding to amino acid changes at the VKORC1 protein at the S149I – S149T and the E155K - E155Q mutations, depending on the rodent species. Computational analysis of binding predictions found out that the brown rat S149I mutation predicted a high reduction of the binding affinity of chlorophacinone and brodifacoum ARs while, the black rat S149T, E155K and E155Q mutations slightly reduced bromadiolone AR binding. These results suggest that these mutations may be one of the causes of the increased resistance to those ARs.

Investigation of a common canine factor VII deficiency variant in dogs with unexplained bleeding on autopsy.

The factor VII (FVII) protein is an integral component of the extrinsic coagulation pathway. Deleterious variants in the gene encoding this protein can result in factor VII deficiency (FVIID), a bleeding disorder characterized by abnormal (slowed) clotting with a wide range of severity, from asymptomatic to life-threatening. In canids, a single FVIID-associated variant, first described in Beagles, has been observed in 24 breeds and mixed-breed dogs. Because this variant is present in breeds of diverse backgrounds, we hypothesized that it could be a contributing factor to unexplained bleeding observed in some canine autopsy cases. DNA was extracted from paraffin-embedded tissue samples from 67 anticoagulant-negative autopsy cases with unexplained etiology for gross lesions of hemorrhage. Each dog was genotyped for the c.407G>A (F71) variant. Experimental controls included 3 known heterozygotes and 2 known homozygotes for the F71 variant, 2 normal dogs with known homozygous wild-type genotypes (F7WF7W), and 5 dogs with bleeding at autopsy that tested positive for anticoagulant rodenticide and were genotyped as F7WF7W. All 67 cases tested homozygous for the wild-type allele, indicating that the common FVIID variant was not responsible for the observed unexplained bleeding. Our work demonstrates the usefulness of retrospective studies utilizing veterinary diagnostic laboratory databases and tissue archives for genetic studies. In the case of FVIID, our results suggest that a singular molecular test for the F71 variant is not a high-yield addition to postmortem screening in these scenarios.

Managing non-target wildlife mortality whilst using rodenticides to eradicate invasive rodents on islands

Invasive rodents are one of the greatest threats to island biodiversity. Eradicating these species from islands has become increasingly practicable in recent decades, primarily using anticoagulant rodenticides. However, this approach also poses risks to native wildlife, and there has been corresponding development in the management of risks to non-target wildlife species. Here we review strategies and tactics used in operational management of non-target risk, using examples from rodent eradication projects conducted on 178 islands where non-target risk assessment and mitigation was a component of the rodent eradication campaign. We identified 17 different tactics within a framework of three strategic approaches: avoidance of risk, minimization of risk, and remediation of the impact of non-target wildlife mortality. We summarize these tactics in terms of their applicability, strengths, and weaknesses for rodent eradication projects in general, plus the potential interactions with achieving rodent eradication. There remains great potential for further innovation in reducing non-target wildlife risks from rodenticide used for invasive rodent eradications on islands, supporting advancement of the social acceptability of the toolset and biodiversity conservation.

The screening for anticoagulant rodenticide gene VKORC1 polymorphism in the rat Rattus norvegicus, Rattus tanezumi and Rattus losea in Hong Kong

Anticoagulants are a major component of rodenticides used worldwide, which function by effectively blocking the vitamin K cycle in rodents. The rat Vitamin K epoxide Reductase Complex (VKORC) subunit 1 is the enzyme responsible for recycling vitamin K, and five substitution mutations (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln and Leu120Gln) located in the VKORC1 could result in resistance to anticoagulant rodenticides. This study carried out a VKORC1-based survey to estimate the anticoagulant rodenticide resistance in three Rattus species (R. losea, R. norvegicus, and R. tanezumi) collected in Hong Kong. A total of 202 rats captured in Hong Kong between 2017 and 2021 were analysed. Sequencing of molecular marker cytochrome c oxidase subunit 1 (COX1) was carried out to assist the species identification, and the identities of 52 lesser ricefield rats (R. losea), 81 common rats (R. norvegicus) and 69 house rats (R. tanezumi) were confirmed. Three VKORC1 exons were amplified from individuals by PCR followed by Sanger sequencing. A total of 47 R. tanezumi (68.1%) contained Tyr139Cys mutation in VKORC1 gene, and half of them were homozygous. None of the collected R. losea and R. norvegicus were detected with the five known substitutions leading to anticoagulant rodenticides resistance, and previously undescribed missense mutations were revealed in each species. Whole genome sequencing was further carried out on some individuals, and single nucleotide polymorphisms (SNPs) were also identified in the introns. This is the first study investigating the situation of anticoagulant rodenticide resistance in the rats collected in Hong Kong. Given that the efficacy of rodenticides is crucial for effective rodent management, regular genetic testing as well as population genomic analyses will be required to both monitor the situation and understand the adaption of different rat haplotypes for integrated pest management. Susceptibility tests for individual rodenticides should also be conducted regularly to assess their effectiveness on local species.

Plastic ingestion in an emaciated red kite (Milvus milvus) in England

AbstractThe red kite (Milvus milvus) was successfully re‐introduced into England in 1989, although the population continues to face anthropogenic threats. In this report, we describe evidence of plastic ingested in the ventriculus of an adult male red kite that was emaciated. In addition, dried blood was found on the feathers overlying both wings, and subcutaneous haemorrhage was identified. Toxicology tests revealed toxic levels (>100 ng/g) of second‐generation anticoagulant rodenticides (difenacoum 3.0 ng/g, brodifacoum 734.9 ng/g) in the liver of this red kite. Three possible contributors to mortality were considered: starvation from the ingestion of plastic preventing normal digestion, collision‐related trauma and second‐generation anticoagulant rodenticide poisoning. This is the first report of plastic ingestion in a red kite. The case highlights the importance of carrying out postmortem examinations as part of post‐release health surveillance and identifies plastic ingestion as a potential anthropogenic threat facing the red kite population in England.

Widespread resistance to anticoagulant rodenticides in Mus musculus domesticus in the city of Barcelona

Control of rodent populations is a big challenge because of the rapid evolution of resistance to commonly used rodenticides and the collateral negative impacts that these products may have on biodiversity. Second-generation anticoagulants are very efficient but different single nucleotide polymorphisms (SNPs) in the Vkorc1 gene may confer resistance in rodents. We sequenced exons 1, 2 and 3 of the Vkorc1 gene from 111 mice (Mus musculus domesticus) captured across the city of Barcelona and found SNPs associated with resistance to first- and second-generation anticoagulants in all of them. Although most of the SNPs were associated with resistance to bromadiolone, we also found SNPs associated with resistance to brodifacoum. Out of all the individuals analyzed, 94.59 % carried mutations associated to introgression events with Mus spretus, a sympatric rodent species. Currently most of the chemical products for rodent control commercialized in the area are based on bromadiolone, although recent public control campaigns have already shifted to other products. Thus, the widespread occurrence of resistant mice to bromadiolone represents a challenge for rodent control in Barcelona and may increase the risk of secondary poisoning of animals preying on this species. Public health managers, pest control companies and citizens should be aware that the use of bromadiolone based products is ineffective and represents a risk for the environment, including human and animal health.

Forensic veterinary diagnosis of dog’s fatal poisoning with anticoagulant rodenticide – bromadiolone

One of the objects of the forensic veterinary examination is the animal’s corpses, the death of which occurred suddenly, or from violent actions, including cruel treatment. A variation of the manifestation of cruelty to animals is their deliberate poisoning. Among the wide variety of toxic substances, pesticides, including rodenticides, occupy a significant place. The aim of the study was to develop an algorithm for forensic veterinary diagnostics and evaluation of dog corpses in case of their sudden death from poisoning with anticoagulant rodenticide – bromadiolone. The objects of the study were the seven dog’s corpses, on which a forensic veterinary examination was carried out for the period from 2010 to 2021 with a clinical diagnosis of acute poisoning with lethal fleeting consequences from poisoning with anticoagulant rodenticide – bromadiolone, established during life. The article shows that the general algorithm for the forensic veterinary examination of the corpse of an animal whose death occurred from poisoning includes the following steps: establishing a list of objects provided for research and information about their condition, conditions for conducting forensic veterinary research, applied methods of studies, their registration numbers (if any); study of the case and the animal’s death anamnesis circumstances; study of veterinary documents and individual case materials related to the examination or provided to the expert additionally at his request; forensic veterinary examination of an animal corpse; study of registration data; external examination of the corpse of an animal; internal examination of an animal corpse; additional studies of the corpse: chemical-toxicological, histological (cytological), microbiological, etc.; forensic veterinary diagnosis; synthesizing research; formulation of conclusions (results); formulation an expert opinion. The forensic veterinary diagnosis, established on the basis of the results of a forensic veterinary examination of the corpses of the dogs under examination, is formulated according to the established rubric structure: the main nosologicalunit and its fatal complication(internal bleeding – hematoperitoneum, hemothorax, bilateral pulmonary edema); accompanying nosological units (acute hemorrhagic gastroenterocolitis, acute hemorrhagic endocarditis, general anemia, congestive venous hyperemia of the kidneys, liver and spleen); background nosological units (undifferentiated hepatopathy and nephropathy, chronic pancreatitis, polyarthritis). The positions of the formulated forensic veterinary diagnosis indicate that they are generally characteristic of acute poisoning. The cytogram data analyzed in the article coincide with the data obtained during the forensic veterinary autopsy of animal corpses, indicating that the poison, from which the death of the dogs under examination occurred, belongs to the group of hemolytic toxins. A chemical-toxicological investigation of the contents of the stomach of the corpses of the dogs under expert identified the poisonous substance of the second generation of rodenticides – bromadiolone at a concentration of 10 mg/kg. A complex of investigations has proved that there is a direct necessary causal relationship between the dog’s death and the nature of the poisoning. Key words: forensic veterinary examination, animals, intoxication, poisonous substances, autopsy, chemical and toxicological research, algorithm.

Anticoagulant rodenticide use in oil palm plantations in Southeast Asia and hazard assessment to non-target animals.

Anticoagulant rodenticides (ARs) are used worldwide for the control of rodent pests and are the main method of control of rat pest populations in agricultural areas. The main aim of this review is to discuss the risk of ARs to non-target wildlife in oil palm areas in Southeast Asia, mainly Indonesia and Malaysia. We discussed AR use in oil palm areas and toxicities of ARs on target and non-target animals. We also reviewed published literature on wildlife species reported in oil palm areas in Southeast Asia and utilizing this information, we assessed the hazard risk of ARs to non-target wildlife in oil palm plantations. ARs are a secondary exposure hazard to rodent-consuming mammalian carnivores, such as leopard cats and civets, and rodent-consuming raptors, such as barn owls. Consumption of dead poisoned prey puts scavengers, such as water monitors, at high risk for AR exposure. Domestic livestock and granivorous birds are at high risk for AR exposure via primary exposure to toxic bait, while omnivores such as macaques and wild pigs are at moderate risk for both primary and secondary exposure to ARs. The effects of ARs on barn owls have been well studied in the field and in laboratory secondary toxicity studies. Thus, the nest-box occupancy and reproductive parameters of local barn owl populations can be monitored as an indicator of the AR exposure level in the area. CLINICAL TRIALS REGISTRATION: No clinical trials were involved in this study.

Enantiomer fraction evaluation of the four stereoisomers of second-generation anticoagulant rodenticides in biological matrices with polysaccharide-based chiral selectors and liquid chromatography tandem mass spectrometry

Numerous cases of wildlife exposure to five second-generation anticoagulant rodenticides have been reported worldwide, and residues of these chiral pesticides in biological matrices are still quantified by achiral liquid chromatography methods. However, they are a mixture of cis- and trans-diastereomers, thus a mixture of four stereoisomers. Their persistence must be evaluated in a differentiated way in the food chain of concerned predator species in order to reduce the environmental impact.This article presents an evaluation of the chiral selectivity of five polysaccharide-based chiral selectors for the four stereoisomers of bromadiolone, difenacoum, brodifacoum, flocoumafen and difethialone. Different chromatographic parameters, influencing the chiral separation, such as organic modifier (acetonitrile, methanol), percentage of formic acid and water content in the mobile phase are systematically tested for all columns. It was shown that little amount of water added to the acetonitrile mobile phase may influence the retention behaviors between reversed phase and HILIC-like modes, and consequently the enantiomer elution order of the four stereoisomers. On the contrary, reversed phase is always the observed mode for the methanol water mobile phase. A suitable combination of all these parameters is presented for each second-generation anticoagulant rodenticide with a description of the enantioresolution, the enantiomer elution order and the retention times of the respective stereoisomers. A method is validated for all stereoisomers of each second-generation anticoagulant rodenticide with chicken liver and according to an official bioanalytical guideline. As an example, the enantiomer fraction is evaluated in the liver of a raptor species (rodent predator) exposed to bromadiolone and difenacoum. The results showed that only one enantiomer of trans-bromadiolone and one enantiomer of cis-difenacoum is present in hepatic residues, although all four stereoisomers are present in bromadiolone and difenacoum rodenticide baits.

Anticoagulant Rodenticide Contamination of Terrestrial Birds of Prey from Western Canada: Patterns and Trends, 1988-2018.

As the dominant means for control of pest rodent populations globally, anticoagulant rodenticides (ARs), particularly the second‐generation compounds (SGARs), have widely contaminated nontarget organisms. We present data on hepatic residues of ARs in 741 raptorial birds found dead or brought into rehabilitation centers in British Columbia, Canada, over a 30‐year period from 1988 to 2018. Exposure varied by species, by proximity to residential areas, and over time, with at least one SGAR residue detected in 74% of individuals and multiple residues in 50% of individuals. By comparison, we detected first‐generation compounds in <5% of the raptors. Highest rates of exposure were in barred owls (Strix varia), 96%, and great horned owls (Bubo virginianus), 81%, species with diverse diets, including rats (Rattus norvegicus and Rattus rattus), and inhabiting suburban and intensive agricultural habitats. Barn owls (Tyto alba), mainly a vole (Microtus) eater, had a lower incidence of exposure of 65%. Putatively, bird‐eating raptors also had a relatively high incidence of exposure, with 75% of Cooper's hawks (Accipiter cooperii) and 60% of sharp‐shinned hawks (Accipiter striatus) exposed. Concentrations of SGARs varied greatly, for example, in barred owls, the geometric mean ∑SGAR = 0.13, ranging from <0.005 to 1.81 μg/g wet weight (n = 208). Barred owls had significantly higher ∑SGAR concentrations than all other species, driven by significantly higher bromadiolone concentrations, which was predicted by the proportion of residential land within their home ranges. Preliminary indications that risk mitigation measures implemented in 2013 are having an influence on exposure include a decrease in mean concentrations of brodifacoum and difethialone in barred and great horned owls and an increase in bromodialone around that inflection point. Environ Toxicol Chem 2022;41:1903–1917. © 2022 Her Majesty the Queen in Right of Canada. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Toxicological responses to sublethal anticoagulant rodenticide exposure in free-flying hawks.

An important component of assessing the hazards of anticoagulant rodenticides to non-target wildlife is observations in exposed free-ranging individuals. The objective of this study was to determine whether environmentally realistic, sublethal first-generation anticoagulant rodenticide (FGAR) exposures via prey can result in direct or indirect adverse effects to free-flying raptors. We offered black-tailed prairie dogs (Cynomys ludovicianus) that had fed on Rozol® Prairie Dog Bait (Rozol, 0.005% active ingredient chlorophacinone, CPN) to six wild-caught red-tailed hawks (RTHA, Buteo jamaicensis), and also offered black-tailed prairie dogs that were not exposed to Rozol to another two wild-caught RTHAs for 7days. On day 6, blood was collected to determine CPN's effects on blood clotting time. On day 7, seven of the eight RTHAs were fitted with VHF radio telemetry transmitters and the RTHAs were released the following day and were monitored for 33days. Prothrombin time (PT) and Russell's viper venom time confirmed that the CPN-exposed RTHAs were exposed to and were adversely affected by CPN. Four of the six CPN-exposed RTHAs exhibited ptiloerection, an indication of thermoregulatory dysfunction due to CPN toxicity, but no signs of intoxication were observed in the reference hawk or the remaining two CPN-exposed RTHAs. Of note is that PT values were associated with ptiloerection duration and frequency; therefore, sublethal CPN exposure can directly or indirectly evoke adverse effects in wild birds. Although our sample sizes were small, this study is a first to relate coagulation times to adverse clinical signs in free-ranging birds.

Prevalence of anticoagulant rodenticide exposure in red-tailed hawks (Buteo jamaicensis) and utility of clotting time assays to detect coagulopathy.

Anticoagulant rodenticides (ARs) continue to be used across the United States as a method for controlling pest rodent species. As a consequence, wild birds of prey are exposed to these toxicants by eating poisoned prey items. ARs prevent the hepatic recycling of vitamin K and thereby impede the post-translational processing of coagulation factors II, VII, IX, and X that are required for procoagulant complex assembly. Through this mechanism of action, ARs cause hemorrhage and death in their target species. Various studies have documented the persistence of these contaminants in birds of prey but few have attempted to use affordable and accessible diagnostic tests to diagnose coagulopathy in free-ranging birds of prey. In our study free-ranging red-tailed hawks were found to be exposed to difethialone and brodifacoum. Eleven of sixteen (68%) livers tested for AR exposure had detectable residues. Difethialone was found in 1/16 (6%), and brodifacoum was detected in 10/16 (62%) liver samples that were tested for rodenticide residues. Difethialone was found at a concentration of 0.18 ug/g wet weight and brodifacoum concentrations ranged from 0.003-0.234 ug/g wet weight. Two out of 34 (6%) RTHA assessed for blood rodenticide had brodifacoum in serum with measured concentrations of 0.003 and 0.006 ug/g. The range of clotting times in the prothrombin time (PT) and Russell's viper venom time assays for control RTHA were 16.7 to 39.7 s and 11.5 to 91.8 s, respectively. One study bird was diagnosed with clinical AR intoxication with a brodifacoum levels in blood of 0.006 and 0.234 ug/g wet weight in blood and liver respectively, a packed cell volume (PCV) of 19%, and PT and RVVT times of >180 s. No correlation was found between PT and RVVT in the control or free-range RTHA, and there was no relationship found between the presence of liver anticoagulant residues and clotting times in the PT and RVVT.

Retrospective Evaluation of Clinical Bleeding in Dogs With Anticoagulant Rodenticide Toxicity—A Multi-Center Evaluation of 62 Cases (2010–2020)

ObjectiveTo evaluate the most common locations of hemorrhage in dogs diagnosed with anticoagulant rodenticide intoxication.AnimalsDogs presenting with hemorrhage secondary to anticoagulant rodenticide intoxication between at two university veterinary teaching hospitals.ProceduresMedical records were searched from the years 2010 through 2020 and all records from dogs treated for hemorrhage secondary to anticoagulant rodenticide intoxication were reviewed. Dogs were diagnosed with anticoagulant rodenticide intoxication based on the combination of known exposure and prolonged coagulation testing, including prothrombin and activated thromboplastin time, or based on gas chromatography-mass spectrometry (GCMS). The diagnosis of hemorrhage was made based on physical exam findings, point-of-care ultrasound findings or radiography.ResultsSixty-two dogs met the inclusion criteria and were included in the study. The most common sites of hemorrhage included: pleural space (hemothorax 37%), pulmonary parenchyma (24%), abdomen (24%), skin/subcutaneous (21%), gastrointestinal tract (18%), pericardium (13%), oral cavity (13%), nasal cavity (11%), ocular (8%), and urinary tract (7%). Overall, forty-five dogs (73%) had evidence of cutaneous or mucosal hemorrhage while thirty-three (53%) of dogs had evidence of cavitary hemorrhage. Forty-five percent of dogs had hemorrhage noted at only one site, while 55% experienced hemorrhage at more than one site. The location of hemorrhage and total number of hemorrhagic sites was not associated with survival or transfusion requirement.Conclusions and Clinical RelevanceIn conclusion, this study highlights that dogs with anticoagulant rodenticide intoxication present with diverse locations of hemorrhage and the majority of dogs had non-cavitary hemorrhage noted.

Comments on “Conservation Letter: Raptors and Anticoagulant Rodenticides”

Comments on “Conservation Letter: Raptors and Anticoagulant Rodenticides”

Establishment and Validation of Anticoagulant Rodenticides in Animal Samples by HPLC-MS/MS, Focusing on Evaluating the Effect of Modified QuEChERS Protocol on Matrix Effect Reduction.

A rapid, accurate, and selective analytical method to simultaneously quantify 13 anticoagulant rodenticides in animal biological samples was developed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) coupled with electrospray ionization (ESI) in negative mode. Samples were extracted and purified based on a modified QuEChERS (quick, easy, cheap, effective, rugged, safe) sample preparation technique. The sample pH and the type of extraction solvent and cleanup sorbent used to estimate the procedure’s effectiveness were optimized. To improve the matrix effects and obtain acceptable recoveries for 13 rodenticides, 0.1 mL/g biological sample and 1 mL acetonitrile (or acetonitrile: EtOAc = 1:1/(v:v)) extraction followed by Florisil/HC-C18/anhydrous Na2SO4 (NaCl) cleanup under alkaline conditions was fully validated and shown to be selective, precise, accurate, and linear in the range from 1 to 100 ng/mL (g). The mean recoveries were between 52.78 and 110.69%, while the limits of detection and quantification ranged from 0.05 to 0.5 and 0.1–1 ng/mL (μg/kg), respectively. Ideal soft matrix effects (≤20%) were observed for the vast majority of rodenticides (>95%) showing either suppression or enhancement. This method meets international criteria and is capable of simultaneously identifying and quantifying anticoagulant rodenticides in animal blood and tissues and can be suitable for the detection of poisoning cases in the field of forensic or public health.

Farmers’ Knowledge, Attitudes, and Control Practices of Rodents in an Agricultural Area of Taiwan

Rodents threaten agricultural industries and food security on a global scale. Rodent management practices routinely involve the use of chemical products, mainly anticoagulant rodenticides (ARs). An understanding of farmer rodent control behaviors is crucial in order to implement management changes to more environmentally friendly practices. In this study, we surveyed farmers in an agricultural area of northwestern Taiwan on their knowledge, attitudes, and control practices for rodent pests. From our survey sample of 126 farmers, rodents were perceived to be the most problematic for vegetable crops, followed by rice, and then fruit. Farmers in the oldest age group and those that perceived rodents to cause extensive damage to their crops were found to have the most negative attitudes toward the pests. One-third of the farmers in our survey stated they currently use rodenticides, with crop type, perceived problems caused by rodents, and attitudes toward rodents found to be important explanatory variables. Our results indicate that the use of rodenticides is reactive; farmers are more likely to apply the chemical products if they perceive rodents to cause damage. Additionally, cost–benefit assessments are likely important in governing rodent control behaviors; farmers may be more inclined to use control products that are subsidized by the government, which include ARs, when they observe damage to their crops inflicted by rodents. We also describe how ecologically based rodent management (EBRM) practices could be feasible and sustainable alternatives to rodenticide use.

Asymptomatic Anticoagulant Rodenticide Exposure in Dogs and Cats-A French and Belgian Rural and Urban Areas Study.

Anticoagulant rodenticides (ARs) are important tools for controlling rodent pests, but they also pose a health threat to non-target species. ARs are one of the most common causes of pet poisoning. However, exposure of domestic animals to subclinical doses of ARs is poorly documented. To study the random exposure of dogs and cats to ARs, feces from animals showing no clinical signs of rodenticide poisoning were collected from a network of French and Belgian veterinarians. We analyzed fresh feces from 304 dogs and 289 cats by liquid chromatography-tandem mass spectrometry. This study showed a limited prevalence of AR exposure in dogs and cats of 2.6 and 4.5% respectively. In both species, access to the outdoors is a risk factor for ARs exposure. In contrast, the sex of the animals did not affect the ARs exposure status. The observation of the ratio of cis and trans isomers suggested primary exposure in dogs, but also in some cats. While primary exposure in dogs appears to be related to the use of ARs as plant protection products, primary exposure in cats may be malicious, as warfarin, an anticoagulant formerly used as a rodenticide and now used only in humans, was found in 4 of 13 exposed cats. Secondary exposure may also occur in cats.Our study showed reduced exposure in dogs and cats, compared to wildlife, which often has high exposure, especially in areas where rodent control is important.

Retrospective analysis of clinical characteristics of and treatment strategies for patients with long-acting anticoagulant rodenticide poisoning.

Long-acting anticoagulant rodenticide (LAAR) poisoning remains a serious public health problem. The aim of this study was to explore the clinical characteristics of different LAARs and a method of making a decision on the VK1 treatment course and the time to stop VK1 treatment safely. This retrospective study compared the clinical characteristics of two LAARs poisoning patients and used multivariate regression method to explore the relationship between blood LAAR concentration and vitamin K1 dose/treatment time. A total of 115 patients with LAAR poisoning were included in this study after screening. Of these, 50 patients attempted to commit suicide. The median LAAR concentration of the patients at admission was 409 (157-1174)ng/mL, and the VK1 treatment duration was 14 (8-34)days. The total VK1 treatment time in patients with LAAR poisoning was positively correlated with admission LAAR concentration. During the maintenance treatment period, the VK1 dosage was positively correlated with blood LAAR concentration. Low dose of VK1 during the maintenance period is indicative of the blood LAAR concentration being relatively low. This provides a basis for judging the LAAR content in the body during the maintenance treatment period.