Pet dogs transfer veterinary medicines to the environment

Swimming emissions from dogs treated with spot-on fipronil or imidacloprid: Assessing the environmental risk

BACKGROUND

Fipronil and imidacloprid are increasingly recognised as contaminants of concern in aquatic environments. This study aimed to quantify swimming emissions from dogs treated with spot-on fipronil or imidacloprid, assess the associated environmental risks and evaluate whether current label instructions on swimming restrictions are adequate.

METHODS

Emissions from swimming were measured for 49 dogs treated with spot-on fipronil or imidacloprid on days 5, 14 or 28 post-application. The environmental risk was assessed by calculating risk quotients, dividing the predicted environmental concentrations by the predicted no-effect concentrations for freshwater ecosystems.

RESULTS

Mean washoff ranged from 4% to 0.4% of the applied dose for fipronil and 10% to 1.4% for imidacloprid across the 5-28-day period. Risk quotients indicate a risk to aquatic ecosystems throughout the products' duration of action.

LIMITATIONS

The results may underestimate emissions for fipronil, as swimming is permitted from 3 days post-application and measurements began on day 5.

CONCLUSION

This study highlights clear ecological risks from spot-on parasiticides and provides evidence that current label instructions on swimming do not provide sufficient environmental protection. Risk-based parasite control strategies and extended swimming restrictions are recommended. Regulatory review of environmental risk assessments and mitigation measures is warranted to protect aquatic environments.

Evaluation of a specific system of extended producer responsibility for veterinary medicines packaging waste

In Portugal, packaging products for veterinary medicines (VM) are subjected to the extended producer responsibility (EPR) scheme coordinated by a Producer Responsibility Organisation (PRO), responsible for the management of both human and VM packaging waste. Despite an 80% recycling target for VM packaging waste, recent years have consistently shown performance below this level. However, there is no compositional data on VM packaging waste in scientific literature, hindering effective problem diagnosis and solution proposals. So, this research proposes a protocol to characterise VM packaging waste entering and leaving a sorting centre and presents the corresponding results. Of the 822.1 kg entering the centre, glass is the predominant material (66.7%, in weight). Often, glass has rubber and metal attached, but this is not recognised as a constraint on recyclability by the glass recycling industry. Biohazardous VM waste was found in the containers dedicated to pharmacologic VM waste, raising a challenge. To evaluate alignment with the principles of circularity, opportunities for waste reduction were assessed but found to be limited by stringent VM regulations. Nevertheless, the potential for recycling could be enhanced through adjustments to the sorting procedures. Moreover, future research should prioritise biohazard risks and operational aspects of recyclability. In addition, discussion and potential reconsideration of recycling rate targets for this waste category are recommended.

A systematic review of fluralaner as a treatment for ectoparasitic infections in mammalian species

Fluralaner (Bravecto™) is a novel isoxazoline ectoparasiticide used for controlling ectoparasites of domestic mammals and is increasingly being used on wildlife. The aim of this systematic review was to evaluate the efficacy, pharmacokinetics, and safety of fluralaner on mammals given its increasing use. The search was performed in GoogleScholar and the SciFinder databases using the terms 'fluralaner' and 'Bravecto™', and was concluded on 30th August, 2024. A total of 250 references were initially saved and reduced to 121 peer-reviewed journal articles using PRISMA guidelines, based on the removal of duplicates, those published in low quality journals (ranked less than Q2), and limiting publications to clinical trials. Articles were then categorised and ranked using the level of evidence, Cochrane 'risk of bias' assessment tool, methodological quality, and study size. Overall, the efficacy of fluralaner has been assessed on 14 mammalian species, and pharmacokinetic investigations conducted on 15. Fluralaner was mostly effective at treating some ectoparasites on captive individuals when there was little chance of re-infection; however, it did not prevent bites from blood-sucking ectoparasites and could not prevent blood-borne pathogen transfer to host animals. Very few studies have investigated the pharmacokinetics of fluralaner, and hence were difficult to compare; however, wombats differed greatly from their eutherian counterparts in their Cmax and t½ values and require further investigation. Overall, fluralaner was deemed moderately safe; however, most studies were classified as fair in terms of quality and most studies were based on small or very small sample numbers. Nineteen studies reported side effects, one of which included signs of severe neurological toxicity, with most of the articles not reporting on safety either positively or negatively. Concerns were raised regarding the extended time fluralaner was detected in faeces and subsequently environmental contamination is a concern. No longer-term impacts of the use of fluralaner have been investigated, and wider implications of the use of this ectoparasiticide have not yet been assessed.

Multiyear and seasonal wide-scale indicators for French surface waters contamination by WFD substances

This study offers an unprecedented valuation of the French surface waters WFD chemical monitoring dataset, covering 101 substances (metals, industrial and persistent organic pollutants (POPs), plant protection product (PPP) and biocides active substances, combustion residues) measured monthly on 4000 sites of the 6 main continental river basins, during 12 years (2009-2020). The concentration data were first made comparable through an original process removing the bias induced by the space-and-time heterogeneity of the monitoring labs performance, to gather a reference workable set of monthly contamination indicators. These were then used to display the substances' seasonal and interannual timeseries, revealing, e.g. the succession of PPP active substances contamination peaking periods in the 6 basins, or the long-term trends of the concentrations of the various chemicals, sometimes evidencing insufficiencies in the monitoring performance. These environmental observations were put in regard of the knowledge of the substances ban, restriction or reduction measures, to assess how streams' chemical quality responds to them. Additionally, the observed contamination features and their variations over the years are discussed in terms of changes in their usages, product substitution, emission sources, and linked to environmental processes like runoff, river dilution and physicochemical conditions. Some original findings and interpretation are provided on glyphosate and AMPA wide-scale data inter-relation, and some light is cast on the efficacy of the recent national policies restricting pesticides use in populated areas. For PPPs, the developed water contamination indicators were compared to tonnage data. We assessed their degree of linear relationship, which we propose to quantitatively express through a substance specific basin-to-river contamination coefficient. The interannual variations of this coefficient appear to be related to the changes in the water contamination seasonal patterns. We were also able to describe and validate the dependency of this coefficient on the molecular properties of the substances, conferring some capabilities for predicting the relative environmental risk induced by non-yet monitored compounds. We finally discuss the relevance of the developed indicators to complement the national chemical pollutants management system currently in place.

High prevalence of veterinary drugs in bird's nests

The environmental impact of insecticides used as ectoparasitic treatments for companion animals is not well understood, since they are not subject to detailed environmental risk assessment. Many of these treatments include active ingredients such as fipronil and imidacloprid that are banned from agricultural use in the EU. These treatments are applied topically and can remain on the animal's fur for an extended period of time. Birds (adults, eggs, and nestlings) using fur as an inner layer for their nests have the potential of being exposed dermally to these chemicals. In this study, we collected 103 nests from blue and great tits, which were lined with fur. Using UHPLC-MS/MS, we detected 17 out of the 20 insecticides we screened for, with the number of insecticides detected per nest ranging from 2 to 11. Fipronil, imidacloprid, and permethrin were detected in 100 %, 89.1 %, and 89.1 % of samples, respectively. The average concentration of fipronil, imidacloprid and permethrin were respectively 115.5 ppb, 376.3 ppb, and 231.1 ppb. Dinotefuran was found at the highest concentration of 7198 ppb in a single sample. Overall, a higher number of either dead offspring or unhatched eggs was found in nests containing a higher number of insecticides, higher total concentration of insecticides or a higher concentration of fipronil, imidacloprid or permethrin, suggesting that contact exposure of eggs to insecticides in nest lining may lead to mortality and lower reproductive success. This highlights the need for a re-evaluation of the environmental risks associated with use of these potent and persistent insecticides on companion animals.

Dog swimming and ectoparasiticide water contamination in urban conservation areas: A case study on Hampstead Heath, London

Widespread occurrence of two ectoparasiticide compounds in the aquatic environment, imidacloprid and fipronil, have prompted concerns about their potential environmental impacts. However, very little focus has been placed on water bodies in urban green spaces used for dog swimming. In this study, occurrence of both substances on Hampstead Heath, London, was compared in ponds with (n = 3) and without dog swimming activity (n = 3), as well as connecting streams above, between, and below these ponds (n = 6). Imidacloprid and fipronil were detected at main swimming points in dog swimming ponds at mean concentrations of 309 ± 104 ng/L and 32 ± 13 ng/L, respectively, indicating a high environmental risk in these samples. Measured concentrations in ponds not accessible for dog swimming were either below the limits of detection or limits of quantification for both chemicals. Across all ponds, there was a strong positive correlation between measured dog swimming activities and concentrations of imidacloprid (R2 = 0.91) and fipronil (R2 = 0.79). Some contamination was detected in connecting streams between ponds. A wider chemical analysis for the presence of urban waste water chemical residue signatures indicated minimal contamination, including in source waters. A survey of visitors who allow their dogs to swim in the sampled ponds confirmed frequent use of products containing imidacloprid and fipronil. In total, 86 % of 101 dog owners were unaware of the potential environmental impacts of products, and 94 % indicated that protecting nature would be an important consideration when selecting products. Besides the current practice of limiting dog access to ponds, information collected on product use and dog swimming practices identified additional opportunities to reduce contamination. We suggest that more cooperation between industry, regulators, veterinarians, green space managers, and the public can reduce risks to urban biodiversity while maintaining recreational benefits for dog owners and dogs.

Factors contributing to pesticide contamination in riverine systems: The role of wastewater and landscape sources

Wastewater treatment plant (WWTP) discharges can be a source of organic contaminants, including pesticides, to rivers. An integrated model was developed for the Potomac River watershed (PRW) to determine the amount of accumulated wastewater percentage of streamflow (ACCWW) and calculate predicted environmental concentrations (PECs) for 14 pesticides in non-tidal National Hydrography Dataset Plus Version 2.1 stream segments. Predicted environmental concentrations were compared to measured environmental concentrations (MECs) from 32 stream sites that represented a range of ACCWW and land use to evaluate model performance and to assess possible non-WWTP loading sources. Statistical agreement between PECs and MECs was strongest for insecticides, followed by fungicides and herbicides. Principal component analysis utilizing optical fluorescence and ancillary water quality data identified wastewater and urban runoff sources. Pesticides that indicated relatively larger sources from WWTPs included dinotefuran, fipronil, carbendazim, thiabendazole, and prometon whereas imidacloprid, azoxystrobin, propiconazole, tebuconazole, and diuron were more related to urban runoff. In addition, PECs generally comprised a low proportion of MECs, which indicates possible dominant loading sources beyond WWTP discharges. Cumulative potential toxicity was higher for sites with greater ACCWW and/or located in developed areas. Imidacloprid, fipronil, and carbendazim accounted for the largest portion of predicted potential toxicity across sites. The chronic aquatic life toxicity benchmarks for freshwater invertebrates were exceeded for 82 % of the imidacloprid detections (n = 28) and 47 % of the fipronil detections (n = 19). These results highlight the ecological implications of pesticide contamination from WWTP discharges and also the potential legacy effects from accumulated soil and groundwater sources. Pesticide management strategies that mitigate both current and historical impacts may improve the health of aquatic ecosystems.

Fecal elimination of fluralaner in different carnivore species after oral administration

Fluralaner is a recent external parasiticide, first of a new class of drugs (isoxazoline parasiticides). It is widely used in companion animals both for its wide spectrum (fleas, ticks and other mites) but also for its ease of use (oral tablets given once for 1 to three months). It is known to be eliminated primarily via the feces (>90%) as the unchanged compound. In zoo carnivores, controlling external parasites is also important and there are no specific products with a marketing authorization to control them. The first objective of this study was to evaluate the pharmacokinetic profile of fluralaner in zoo carnivores. The second objective was to demonstrate that fluralaner can be eliminated over a prolonged period of time, thereby raising questions about its potential impact on non-target species such as arthropods. After adjusting the oral dose using allometric equations, animals were dosed and fecal samples were collected on a regular basis for up to three months to determine the fecal elimination curve of fluralaner as a surrogate of plasma kinetics (for ethical and safety reasons, plasma samples were not considered). All samples were analyzed with a validated LC-MSMS technique. Our results show that, despite limitations and a limited number of animals included, most carnivores eliminate fluralaner in their feces for several weeks to months (in Lions, fluralaner was still detectable after 89 days). To our knowledge, this is the first study demonstrating such a long elimination period in animals. Further studies would be required to investigate the risk associated with the presence of active residues in other carnivore feces for the environment, especially in dogs and cats, considering the large use of this class of compounds.

Pharmacological studies and pharmacokinetic modelling to support the development of interventions targeting ecological reservoirs of Lyme disease

The development of interventions targeting reservoirs of Borrelia burgdorferi sensu stricto with acaricide to reduce the density of infected ticks faces numerous challenges imposed by ecological and operational limits. In this study, the pharmacokinetics, efficacy and toxicology of fluralaner were investigated in Mus musculus and Peromyscus leucopus mice, the main reservoir of B. burgdorferi in North America. Fluralaner showed rapid distribution and elimination, leading to fast plasma concentration (Cp) depletion in the first hours after administration followed by a slow elimination rate for several weeks, resulting in a long terminal half-life. Efficacy fell below 100% while Cp (± standard deviation) decreased from 196 ± 54 to 119 ± 62 ng/mL. These experimental results were then used in simulations of fluralaner treatment for a duration equivalent to the active period of Ixodes scapularis larvae and nymphs. Simulations showed that doses as low as 10 mg/kg have the potential to protect P. leucopus against infestation for a full I. scapularis active season if administered at least once every 7 days. This study shows that investigating the pharmacology of candidate acaricides in combination with pharmacokinetic simulations can provide important information to support the development of effective interventions targeting ecological reservoirs of Lyme disease. It therefore represents a critical step that may help surpass limits inherent to the development of these interventions.

Temperature-bounded development of Dirofilaria immitis larvae restricts the geographical distribution and seasonality of its transmission: case study and decision support system for canine heartworm management in Australia

Dirofilaria immitis is the causative agent of canine heartworm disease. We used the established heartworm development unit (HDU) principle to map the extrinsic incubation period (EIP) of D. immitis in Australia using historical weather data from 2013-2022. We found weather conditions suitable for EIP completion showed substantial seasonality and geographical variability. Whilst a considerable percentage of the Australian territory showed suitable weather conditions to always support EIP completion (17%), only 2.7% of the 2021 Australian human population lived in this region. Therefore, 97% of the population lived in an area that changed its EIP suitability within the study period. EIP completion is required prior to D. immitis transmission, meaning that infection risk of D. immitis is seasonal and location-dependent, being disrupted each year for most of the human population's dogs. We developed an online, open access tool allowing us to visualise EIP completion across Australia historically and in near real-time. We aim to support veterinarians to make risk-based recommendations for dirofilariosis prevention by using the tool, available at https://heartworm-mapping.adelaide.edu.au/shiny/.

Human biomonitoring of neonicotinoid exposures: case studies after the use of a spray-agent to ornamental plants and a topical medication to pets

Acetamiprid (ACE) and imidacloprid (IMI) are insecticides of global importance and are used as spray and watering agents for ornamental plants to control biting and sucking insects or as topical medications on pets to remove and control fleas. Human biomonitoring data on ACE and IMI exposures when applying these products are limited. We investigated exposures to ACE and IMI in male volunteers after the domestic application of either an ACE-containing agent or an IMI-containing spot-on medication. Complete and consecutive urine samples were collected for up to 56 h after application. Urine samples were analyzed for ACE, IMI, and their respective metabolites (N-desmethyl-ACE, IMI-olefin, and sum of 4-/5-hydroxy-IMI) by liquid chromatography-tandem mass spectrometry. Fairly uniform concentrations of N-desmethyl-ACE could be observed before and after orchid treatment, so that an ACE exposure associated with orchid treatment can most likely be excluded. In contrast, after the application of the IMI-containing medication, elevated concentrations of IMI, 4-/5-hydroxy-IMI, and IMI-olefin were quantified in urine samples post-20 h with maximum concentrations of 3.1, 14.9, and 8.0 μg/g creatinine, respectively, well above general background levels. Nevertheless, the IMI intake (10.6 μg/kg bw), calculated from the excreted amounts, was around five times below the current European acceptable daily intake. Based on the case results here, household exposures to ACE and IMI after spray treatment of ornamental plants and anti-flea treatment of dogs can be regarded as low and safe. However, people regularly applying neonicotinoid-containing formulations, such as professional gardeners and employees in animal shelters, should be studied in more detail.

Topical, contact, and oral susceptibility of adult Culicoides biting midges (Diptera: Ceratopogonidae) to fluralaner

BACKGROUND

Culicoides biting midges (Diptera: Ceratopogonidae) are economically important blood-feeding pests closely associated with livestock production. They are the principal vectors of two hemorrhagic disease viruses affecting both wild and domestic ruminants within the US: bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). BTV impacts the US agriculture sector through direct commodity loss and strict international livestock trade restrictions. Yet, despite posing a considerable threat to US livestock, Culicoides are understudied, and management strategies are lacking. Current control tools for Culicoides are limited to synthetic chemicals, predominantly pyrethroids. With limited products available for livestock producers, proper pesticide rotation is difficult. The present study investigates the efficacy of fluralaner, an isoxazoline insecticide, beyond its current labeled use as an ectoparasiticide in anticipation of adding a new class of pesticides into rotation for use against biting midges.

METHODS

The efficacy of fluralaner was evaluated by conducting contact, topical, and oral toxicity bioassays on adult female Culicoides sonorensis. Contact toxicity was assessed by using a modified WHO cone assay, which simulates exposure through landing on an insecticide-treated surface. A modified WHO topical toxicity assay, in which fluralaner dilutions were administered to the lateral thorax, was used to assess topical toxicity. For evaluation of oral toxicity, females were offered a blood meal spiked with fluralaner in an artificial membrane feeding system to simulate a systemic insecticide.

RESULTS

Contact exposure of fluralaner did not cause extensive or consistent mortality. Even the highest concentration tested (100 mg/ml) resulted in an average of only 24.3% mortality at 24 h, and mortality did not significantly differ between exposed and control midges at any concentration. One hundred percent mortality was consistently achieved at concentrations of 1 mg/ml when fluralaner was applied topically. The LC50 for topical exposure to fluralaner at 24 h was estimated to be 0.011 mg/ml. Oral exposure to fluralaner through ingestion of a spiked blood meal proved to be the most effective exposure method, significantly increasing mortality in a dose-dependent manner at 1 h post-exposure. The LC50 at 24 h following ingestion was 14.42 ng/ml.

CONCLUSION

Our results suggest that fluralaner is a viable candidate for use as an insecticide against adult biting midges if exposed orally, such as in a systemic given to livestock. As withdrawal period requirements for meat animals present unique yet definitive challenges, pharmacokinetic studies of isoxazoline drugs need to be pursued and finalized for livestock before fluralaner may be used as a management strategy in this manner. Alternatively, livestock not raised for consumption, such as hair sheep, would directly benefit from administering oral fluralaner as a component of a BTV disease management program.

To flea or not to flea: survey of UK companion animal ectoparasiticide usage and activities affecting pathways to the environment

Due to the convenience and efficacy of modern ectoparasiticides, routine prophylactic use has become commonplace for dogs and cats. However, the environmental consequences of this large-scale use are not well-understood, and multiple potential pathways for ectoparasiticides to the environment exist. Of particular concern is the potential for topically applied ectoparasiticides to pass to waterways, both down-the-drain via wastewater treatment plants and directly through swimming. In this online cross-sectional survey of 1,009 UK cat and dog owners, we investigated ectoparasiticide usage and the frequency of activities that are likely to result in transfer of the active substance to the environment, with a focus on pathways to waterways. A total of 603 dog owners and 406 cat owners completed the survey. Amongst dog and cat owners, 86.1% and 91.1% had administered an ectoparasiticide treatment to their pet in the preceding 12 months. Imidacloprid was the most frequently administered ectoparasiticide in both cats and dogs, followed by fluralaner in dogs and fipronil in cats. Eighty-four percent of owners who applied topical ectoparasiticides to their dog said they were aware of product warnings regarding swimming and bathing after application. Spot-on treated dogs were reported to swim significantly less frequently than non spot-on treated dogs (p = 0.007); however, 36.2% were reported to swim at least monthly. Similarly, significant differences were found in bathing frequency between spot-on treated and non spot-on treated dogs, with treated dogs less likely to be bathed at frequent (weekly) intervals, however 54.6% were reported to be bathed at least monthly. Washing of bedding was unaffected by ectoparasiticide treatment, and 87.8% of dog owners and 69.1% of cat-owners reported washing their pet's bedding at least every 3 months, suggesting that residue washoff from bedding may be occurring for most topically treated animals. Results suggest that transfer of ectoparasiticides to the environment is likely to occur for many of the millions of animals treated annually in the UK, with imidacloprid spot-on treated dogs estimated to swim, be bathed and have their bedding washed over 3.3 million, 5 million and 6.3 million times per year, respectively.

Plague mitigation for prairie dog and black-footed ferret conservation: Degree and duration of flea control with 0.005% fipronil grain bait

Sylvatic plague, a primarily flea-borne zoonosis, is a significant threat to prairie dogs (Cynomys spp., PDs) and their specialized predators, endangered black-footed ferrets (Mustela nigripes, BFFs). Host-fed fipronil baits have proven effective in controlling fleas on PDs for the purposes of plague mitigation and BFF conservation. Currently, annual treatments are the norm. We tested the long-term efficacy of fipronil bait treatments with black-tailed PDs (C. ludovicianus, BTPDs) and BFFs in South Dakota, USA. During 2018-2020, we provided BTPDs on 21 sites with grain bait formula, laced with 0.005% fipronil (50 ​mg/kg); 18 non-treated sites functioned as baselines. In 2020-2022, we live-trapped, anesthetized, and combed BTPDs for fleas. Flea control was significant for at least 639-885 days. Flea abundance on the treated sites was < 0.5 fleas/BTPD for ∼750 days. During 2020-2022, we sampled BFFs for fleas on 4 BTPD colonies treated with fipronil grain bait and 8 non-treated colonies. Flea control was significant with BFFs, but flea abundance began to rebound within ∼240 days post-treatment. When feasible, the combination of insecticide treatments, such as fipronil baits, and BFF vaccination against plague provide a "two-pronged" protection approach for these endangered carnivores. If fipronil bait treatments are less effective with predatory BFFs than PDs, as found herein, the "two-pronged" approach might be used to protect BFFs and biennial fipronil bait treatments might be used to protect PDs. If BFF vaccination is not possible, or few BFFs can be vaccinated, annual fipronil bait treatments might be used as a precaution to protect BFFs. Flea densities might be surveyed to determine when/where more frequent treatments seem useful.

Neonicotinoids: Still present in farmland birds despite their ban

Neonicotinoids (neonics) are the most widely used insecticides worldwide and are considered to be of low risk to non-target organisms such as vertebrates. Further, they are reported to be rapidly excreted and metabolized, reducing their potential toxicity. Nevertheless, growing evidence of adverse effects of neonics on farmland bird species raise questions about the purported harmless nature of these pesticides. We attempted to search for pesticide residues in species of different trophic levels and at different life stages, by using multiple bird monitoring programs on a Long-Term Socio-Ecological Research (LTSER) platform. Three passerine birds-the blackbird (Turdus merula), cirl bunting (Emberiza cirlus), and common nightingale (Luscinia megarhynchos)-that feed on seeds and invertebrates were monitored during their reproductive period, and the grey partridge (Perdix perdix) that feeds on seeds was monitored during its wintering period. We also monitored chicks of an apex predator-the Montagu's harrier (Circus pygargus)-that preys mostly upon common voles but also upon insects. We found that the birds' blood samples showed presence of residues of five neonics: three banned since 2018 in France-clothianidin, thiacloprid, and thiamethoxam-and two-dinotefuran and nitenpyram-used for veterinary purposes only. While none of these neonics was detected in blackbirds, all were present in grey partridges. Clothianidin was detected in all species, except blackbirds. Concentrations of the three banned neonics were similar or higher than concentrations found in birds monitored elsewhere before the ban. These findings raise questions about the persistence of neonics within the environment and the mode of exposure to wild fauna. Future investigations on the sublethal effects of these neonics on life-history traits of these farmland birds may help in providing a better understanding of the effects of exposure of bird populations to these insecticides, and also to the consequent effect on human health.