Hi All,
Welcome to topic 2 for 624EHS - Contemporary Issues in Equine Science.
This topic is all about parasite control practices. DL students, make sure that you look at the launch PowerPoint and video, which has been posted in the Classroom. ALL students are required to contribute to this blog as part of their CW3 assessment. All students have from now until 11:59 pm on Friday 9th of December 2022 to contribute to this blog, to debate the issues surrounding parasite control practices within the equine sector. Ensure you can also evidence your opinions and remember that you are also required to submit a reference list (word document emailed to module leader) by 11.59 pm on Friday 9th of December 2022. You will be graded on the quality and quantity of both your blog contributions and your reference list. Remember, the point of this is to debate the issues, so you should be replying to each other's posts. I will be keeping an eye on the blog, but if you have any issues, you should email me. Please remember to register your name with your comments so that I know who has contributed with which comment.
Rosa
Parasite control is extremely important within equine management, infection from either endoparasites or ectoparasites may lead to serious health implications (Wilkes et al., 2019). Control of parasites by administering anthelmintics is largely used within the equine industry. However, Wilkes et al., (2019) found that the frequent use of anthelmintics alongside poor management practices has led to immune resistance and better strategies are necessary to improve this.
ReplyDeleteThere have been changes in approaches to worm control in the UK with the use of faecal egg counts on the rise. Yet many owners still do not utilise these practices. And there seems to be a lack of knowledge and understanding around testing leaving important gaps in knowledge distribution (Tzelos et al, 2019).
DeleteThere needs to be a focus on knowledge sharing in the future to prevent overuse of anthelmintics and thus anthelmintic resistance. An increase in owner perceived knowledge increases the intention to use FEC and the impact of perceived knowledge can be influenced by factors such as social media (Vineer et al, 2017).
DeleteParasite control strategies worldwide remain over-reliant on anthelmintic use. Wilkes et al. (2019) investigated parasite control practices in thoroughbred and standarbreds stud farms in and investigate the frequency of use of management factors that have been associated with the likelihood of promoting or delaying anthelmintic resistance and found that there is a lack of awareness of the importance of non-chemotherapeutic strategies in integrated approaches to parasite control aimed at delaying the development of drug resistance.
DeleteSimilarly, Nielsen et al. (2018) investigated parasite control strategies used by equine owners in the United States and found that most owners dewormed 2–3 times a year with ivermectin being the most commonly used anthelmintic; about 22% of owners used fecal egg counts (FEC) in some form, with less than 10% using them on a regular basis. Less than 5% made use of fecal egg count reduction tests (FECRT).
Deletethis study illustrated a general need for more effective communication of current parasite control guidelines, especially the need for parasite surveillance in the form of FEC and FECRT.
Whereras Nielsen et al. (2018) had a larger pool of data (the study was carried out in 28 states, representing 70.9% of all equine operations in the United States, with at least five equids present, recruting overall 380 operations) and Wilkies at al. (2019) only managed to recruit 75 operations (25% response rate) which might be considered a weakness in this study, both studies highlight the need for greater veterinary involvement in the implementation of more sustainable parasite control practices with greater emphasis placed on surveillance through FEC and FECRT testing. Also, espiecially in the study by Nielsen et al. (2018) there is evidence that equine owners do not differentiate their parasite control efforts between different horses and thier individual requirements, further highligthing a need for more emphasis in teaching and discussing about these aspects to equine owners.
DeleteWilkes et al, 2019 carried out a questionnaire to obtain Information regarding parasite control practices currently used on Thoroughbred and Standardbred studs in Australia and investigate the frequency of use of management factors that have been associated with the likelihood of promoting or delaying AR.
DeleteSeventy-five completed questionnaires were received, Ninety-seven per cent of respondents used anthelmintics to manage worms in horses. The most commonly used anthelmintics in mares and foals were ML-praziquantel combinations and less than 5% of respondents used targeted treatment regimens. The majority of respondents (97%) considered AR to be important; however, few respondents were aware of the use of FEC reduction tests for monitoring of drug efficacy.
The implementation of pasture hygiene practices was variable. Manure was removed from the pasture on 60% of farms, using manual, machine, harrowing or dung beetle methods. Properties that moved horses to a new paddock after anthelmintic administration were 10 times less likely to undertake pasture manure removal. Other pasture management practices included mowing/slashing, fertilising, seeding, ploughing/harrowing, pasture rotation and spelling and co-grazing. Most respondents rotated pastures between grazing groups (82%) and rested pastures (88%). Co-grazing with cattle was reported by 36% of respondents.
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DeleteLimitations – 75 completed questionnaires from respondents from several Australian states and the results reflect parasite control practices over a broad geographical area. Bias likely occurs in questionnaire studies of equine parasite control as respondents may be more conscientious and have different attitudes to control methods than nonrespondents which may be reflected in the results. As such, the proportion of Australian farms that do not undertake pasture management and other strategies to reduce anthelmintic use may be greater than reported in this study.
DeleteFurthermore prophylactic use of anthelmitic drugs, which was not their intended use, is no longer acceptable in veterinary medicine due to the prevalence of anthelmintic resistance: anthelmintics are meant to be one part of a parasite control program where they are used to treat individuals who have been diagnosed with clinical parasitism in order to decrease disease-associated morbidity, contrary to what common practice does (Tinkler S.H., 2020)
DeleteIn a study completed by Allison etal., (2011), it was found that 45% of respondents were not satisfied with their livery yards worming program and that less than half of respondents consulted their vets regarding worming schedules ect. It was also highlighted that only 25% of respondents wanted to change their anthelmintic programme. This study highlights the need for more owner knowledge, as there was a clear lack of current knowledge available when this study was completed. However, the paper is over 10 years old, therefore owners may be more aware of resistance and managing paricites. Alternately, there could be complications in Faecal egg counts in large groups on livery yards due the range of different management techniques, making it hard for livery yard owners to pinpoint effected horses, and therefore find a blanket approach is more acceptable.
DeleteHowever, critically, a study completed by Lind etal., (2007) found that 72% of respondents found parasites a “minor problem” and that they had no issues past or present with them cause harm to equines. This study causes confusion among the equine industry, due to the heavy literature around issues regarding worming and the resistance. However, this study could be considered outdates due to the length time since publication, therefore suggesting a similar study should be completed, with present knowledge.
DeleteAn alternative viewpoint is that of frequency of admiration. For example, a study, found that only 19% of owners wormed their horses based on FEC. Also, it was found that 73% of owners only estimate their horses weight (Stratford etal 2014), therefore there are a large number of horses that are being wormed in appropriately, but also being given the incorrect dosage. This could also be a contributing factor as why resistance is so prevenient. However, this could contradict Lind etal.,(2007), due to the lack of correspondence between horses and lack of parasite relates issues.
DeleteThis is Supported by Mctigue etal., (2022) that found that a key part of anthelmintic resistance is the lack of knowledge and awareness of bodyweight, and the rate of resistance is reducing but if the knowledge of owners worming application, then this won’t continue. Therefore, adding to the increasing pressure for owners to be educated on recent developments of resistance.
DeleteNearly all countries have implemented prescription-only restrictions of anthelmintic usage by law, which is in contrast to USA and U.K, where all anthelmintic products continue to be available over the counter or online (Becher et al., 2018). Becher et al., (2018) completed a survey based study in which they aimed to describe and compare equine parasitic control strategies throughout Germany, Netherlands, Austria, USA and Denmark. 3092 questionnaires were completed and it was found that Denmark used significantly more fecal egg count strategies and administered significantly less anthelmintics treatments per horse per year. This arises a question as to why, because Austria and Germany have had prescription-only treatments for 30-40 years however their results were similar to America who can buy treatment over the counter without prescription. Therefore, legislation alone cannot be the underlying factor (Becher et al., 2018).
ReplyDeleteFurther studies need to be completed to find out what Denmark does different to have these significant differences in their parasite management and treatment strategies.
Tzelos et al, 2019 found that only 38% of owners obtained advice from their veterinarian with regards to worm control. Plus also finding that 43.8% of owners purchase anthelmintics via the internet. These issues could be addressed by altering prescribing legislation in the UK to promote better quality face-to-face interactions when anthelmintics are sold and minimise the amount of anthelmintics purchased online (Tzelos et al, 2019).
DeleteSimilar to what Easton et al, 2016 previously found when investigating the use of anthelmintics with 76.2% of owners buying anthelmintics online. Owners who sought advice from veterinarians were more likely to be recommended to use faecal egg counts (FEC) (Easton et al, 2016).
DeleteIn regards to the comment about seeking advice from a veterinarian; the paper by Tzelos et al., (2019) found that 38% of owners obtained advice from their veterinarians, yet this study shows that a percentage then went to buy the recommended anthelminitc treatment online. It can be taken from this that owners may have had a brief conversation with their vet to ask which would be the best anthelminitc to treat their horse at the specific time, with them then buying this online as a cheaper option. However, face-to-face interactions with veterinarians would be more appropriate as the veterinarian is then 'more likely' to offer a FEC before determining which anthelminitc the owner should use. Overall, advice from the veterinarians may be sought but it does not mean it was the correct interaction (Tzelos et al., 2019; Easton et al., 2016).
DeleteThe paper completed by Tzelos et al., (2019) was a questionnaire based study which comprised of 58 questions to understand if there was a continued improvement in the uptake of evidence-based control practices by horse owners in the U.K. A total of 652 surveys were returned with 519 of these fully completed, which is a large number of responses to work with from all around the U.K. The questions gathered a lot of information on what the horse owners did in regards to worming, what type of horses they owned, where they were kept, yard practices such as quarantining new horses and many more questions. These gave a great overview and understanding of the ways in which horse owners in the U.K. go about worming practices and also looking at their knowledge in this topic area. The main limitation to this study is a possibility of bias due to being a questionnaire. Respondents may write responses which determine them to be a better owner, or what they think the person wants to hear, so all responses may not be answered truthfully. Another limitation was that this study was distributed online, therefore only owners who have access to the internet and used social platforms could find this questionnaire in order to create a response. Despite these, this study gathered many results and this enabled a good understanding of current worming practices and knowledge within the U.K. Which concluded a notably slow change from interval treatment to targeted treatment strategies which is a positive, however still a large proportion of owners are buying anthelmintics online. Therefore, changes are occurring, just at a slow pace and further changes in the industry could be made such as altering prescribing legislations (Tzelos et al., 2019).
DeleteRegarding Vetanairian knowlege, O’meara and Mulcahy, (2002) found that veterinary professionals, do not consider worming a high priority role and that this could highlight a gap in their knowledge as well as owners ect. This provides confusion, due to owners and cares looking to veterinarians for advice all over the world, and that if the lack of knowledge is there in professionals the how are owners meant to be educated. This study was a old study and there may be improvement in knowledge currently, however, there is still need for, more development in order to keep paricite infestation at a minimum
DeleteContinuing from international knowledge, Similar to the UK, it was found in New Zealand that only 20% of respondents in a recent study went to there veterinarians for advise regarding worming schedules. Therefore highlighting this being a global problem and not to a national problem, regarding the lack of certainty that vets offer. Also again questioning whether vets have significant knowledge on the situation. (Bolwell etal, 2015)
DeleteRendle, (2021) also, states blanket worming is not appropriate in autumn, due to availability if diagnostic techniques. This could therefore cause confusion for owners due to clinicians suggesting that equines should be wormed once a year (Dorset Equine Veterinary Services, 2022). However, by testing regularly, and with testing becoming available in a range of different places from vets to feed shops, it questions weather previous statements (worming yearly) were made due to the lack of recourses and facilities of these diagnostic techniques as a way of ensuring equines got wormed once a year regardless. Therefore, creating questions as to why vets are still recommending this strategy
DeleteA way of encouraging vets to improve there knowledge could be knowledge is that not only will it help decrease resistance, and parasite infestation. It will also help increase veterinarian sales, profit, and client enjoyment, due to more services being used (Rendle, 2018). This is therefore another incentive for veterinarians to become educated. However, the morality of this point of view could be questioned, due to the legislations that vets must adhere to state they must prevent animals form harm.
DeleteThere has been a shift in the species responsible for parasitic related deaths. Cyathostomin infection has replaced cases of death previously caused by Strongylus vulgaris and tapeworms. Fatal cyathostominosis cases have been increasing since the year 2000 and cyathostominosis has remained the most frequent cause in cases of death from parasitic origin (Salle et al, 2020).
ReplyDeleteLimitations though apply to the study cited, Sallè et al. (2020) as it only took in consideration young horses between the ages of 2-24 months, 90% of which came from Normandy and it looked at of non-strongylid communities and an assessment of cyathostominosis and verminous arteritis so it's not fully comprehensive of parassitic species. Furthermore as acknowledged by the authors, there is no other example of comprehensive longitudinal analysis of equine parasite communities in any other region than Kentucky so this might pose a limitation to the authors findings as there is no available comparison whith other regions or countries.
DeleteAs previously highlighted it can be challenging creating a working schedule for such wide ranges of equines with different management techniques, such that is found at livery yards. It is therefore important that parisite control in these types of cases should be completed with assistance from vets in order to help prevent resistance (Barker, 2015)
DeleteThere is a need to carry out FWECRT to fully evaluate the threat of anthelmintic resistance. Relf et al, 2014 found that after treatment with anthelmintics including moxidectin when a FWECRT was carried out the egg reappearance period was shortened, suggesting some resistance to the drug (Relf et al, 2014).
ReplyDeleteManagement / husbandry of the horse also needs to be a large consideration, as well as the need for faecal worm egg counts (FWEC) and faecal worm egg count reduction tests (FWECRT), there is a need for pasture and stable management to aid in parasite control. Horses kept in large numbers (>30 horses/ha) were found to have significantly high FWEC results than those kept in smaller numbers (Joo et al, 2022). Other management factors that have been associated with high FEC results include all day grazing and not mowing roughs on the pasture (Fritzen et al., 2010). The removal of faeces from the pasture plays a crucial role in reducing infection pressure in the environment (Kaplan and Vidyashankar., 2012 ; Stratford et al., 2013).
ReplyDeleteAs well as those management factors, other techniques employing centrifugation-enhanced flotation have been shown to perform with diagnostic sensitivities around 60% for detecting burdens of at least one worm and 90% for detecting infections of 20 worms or more (Kjær et al.,2007; Nielsen, 2022). Thus, these modified egg counting techniques can detect larger tapeworm burdens with a high level of reliability.
DeleteNew tests such as the FECPAKG2, optimised for livestock but yet t be approved for equids, are reported to allow owners to perform FECs on their own animals without the need for a lab and reducing the inaccuracies caused by the problematic storage of samples prior to testing. The accuracy of this new method was tested in a study conducted by Tyson et al. (2020) which found that the FECPAKG2 performed equally as well as the control method (an accepted non-remote equine FEC method). The mean percentage accuracy of the G2 test compared to the control values was 101%. The relative accuracy of the G2 method compared to the control method was not affected by the level of infection and it was concluded that the FECPAKG2 method is suitable for performing FECs in horses. The availability of such a methods, to test for parassitic burden, will further encourage horse owners to perform FECs for targeted treatments further delaying anthelmintics resistance.
DeleteWith the recommendation that regular fecal egg counts should be performed, there is a need for improving the understanding of the movement of parasite eggs during flotation. Traditionally, and in order to facilitate easier identification and/or enumeration, samples are analysed after separating eggs from other fecal particulates by exposing them to a solution with a density higher than that of the eggs, but lower than the remaining fecal contents.
DeleteNorris et al, 2019 developed a novel method for viewing and analyzing the speeds and movement patterns of eggs of endoparasites as they interact with flotation solution. This may be of use in future efforts to produce type-specific endoparasite egg flotation protocols and can aid in optimizing egg flotation protocols for reliably detecting parasite ova of clinical significance.
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ReplyDeleteDespite all of this, there are of course limitations to FEC strategies which have been discussed by Nielsen, (2022). Fecal egg counts are not clinical diagnostic tools and parasite eggs in equine faeces are a common finding in healthy horses, therefore they do not dictate pathology or disease.
ReplyDeleteThe larval stages of strongyle infections are the pathogenic stages and these do not produce eggs. Ascarid and strongylid FEC do not reflect the size of the intestinal worm burden. Nielsen et al., (2010) completed a study which valuated linear correlations between ascarid and strongylid egg and worm counts in a largedata set and found correlation coefficients to be less than 0.30. Thus, a faecal egg count does not allow a quantitative assessment of infection intensity, so a horse with a high egg count does not necessarily harbour more worms than one with a low count (Nielsen, 2022)
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DeleteSchurer et al, 2014 carried out testing upon fecal samples under various storage temperatures which simulated diagnostic and research protocols. Fresh; −80 °C for 3 days; −20 °C for 30 days; and −80 °C for 3 days followed by −20 °C for an additional 30 days. Eggs were counted using a quantitative double centrifugation sucrose fecal flotation (modified Stoll egg count). Repeated measures ANOVA was used to detect differences in egg counts Counts for P. equorum and strongylid type eggs which decreased significantly following freezing.
DeletePost-freezing, some samples that had been positive on fresh examination became negative for Parascaris and strongylid eggs.
This study suggests that protocols requiring freezing artificially lowers recovery of eggs of Parascaris and strongylid nematodes in fecal surveys.
However, recovery rates for eggs of other helminth species as well as sporocysts of Sarcocystis spp. were relatively robust compared to the freshly tested fecal samples. This is reassuring for large scale fecal surveys needed for fecal egg count reduction analyses following treatment, and for surveillance in animal populations.
It also suggests that parasites commonly found in equine fecal samples are more sensitive to subzero temperatures and should be processed fresh whenever accurate FECs are needed such as for drug efficacy trials.
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DeleteAgreeing with previous statements, Snalune, (2008) found high mucosal burdens don’t show in faecal egg count, therefore, highlighting the need for more accurate way of testing to be completed, in a way is easy and not expensive for owners. This could also question the accuracy for all types of tests completed, such as the Sliva test for tape worm, due to owners’ accuracy as well as test accuracy. However, due to the age of the study also with the recent media influence regarding worming prevalence, this study could be outdated.
DeleteAnother factor that might impact on parassitic burden and anthelminitics resistance is climate change. The analysis conducted by Sauermann et al. (2020) found that that without mitigation, climate change is likely to accelerate development of anthelmintic resistance as climate change has effects on pathogens or parasites modifying occurrence and distribution range. Under anthelmintic treatment the reproductive advantage to surviving adult worms is greater because the period over which eggs successfully develop is longer, hence there is a shift of successful reproduction in favour of resistant genotypes. Under the more favourable projected climate conditions and unchanged management regimes, the ratio of the reproductive rate of susceptible versus resistant parasites will shift towards the resistant parasites.
ReplyDeleteSauermann et al. (2020) findings suggest that the changing environmental conditions in temperate climates will further lessen the ability to effectively control livestock parasites with anthelmintic treatments only and how non-drug related parasite control strategies will be increasingly necessary with predicted climate changes.
DeleteSauermann et al., (2020) explain that if parasite populations increase in size due to climate conditions, owners and veterinarians are likely to respond to this by administering greater quantities of anthelmintic drugs, therefore, further increasing the resistance. However, a limitation to this study is that only 16 horses were used for this investigation and only three locations were used so it is a small based study that could benefit from being further proven in a larger scale.
DeleteCanhão-Dias et al. (2020) reviewed the efficacy of new predatory fungi products as promising tools for gastrointestinal parasite control as the increasing hazards of drug resistance and ecotoxicity, biological control with predatory fungi stands out as a good tool for future parasite management, whether as a complementary treatment or as an alternative to standard parasite control. Overall despite all the advances in understanding predatory fungi, there is scarce information about the fungi’s potential impact on the soil microbiome. As such, more studies need to be conducted in order to fully understand how beneficial these treatments are in the long-term but there is evidence that treatments with nematophagous fungi reduce the number and viability of gastrointestinal parasites’ larvae and eggs, both in vivo and in vitro experiments, in distinct animal species.
ReplyDeleteIn research to find alternative means of controlling parasite burden, Payne et al, 2013, carried out a screening crude extracts from 37 species of Australian native plants for their anthelmintic activity in vitro against cyathostomin larvae (development from egg to third larval stage), with the aim of identifying those species that may be suitable for incorporation into sustainable parasite management programs.
ReplyDeleteResults from some species of plants completely inhibited larval development (100% inhibition compared to the control), while another 10 species caused 90% inhibition at the initial screening concentration.
Results suggest that a number of Australian native plants have significant anthelmintic activity against cyathostomin larval development in vitro.
There is potential for these plants to be used as part of sustainable parasite control programs in horses, although more research is needed to identify the compounds responsible for the anthelmintic effects and confirm their activity in vivo (Payne et al, 2013).
(Apologies for the older papers, I have no access to WCG library at the moment, so I am having to use google scholar)
The study by Payne et al., (2013), was completed in vitro and further studies would need to be completed in vivo to reiterate their results. There are multiple factors relating to physiology of the host and nematodes that may alter the bioavailability of the active compounds. As an example, host pharmacokinetics may limit the amount of active compounds reaching the nematodes. So these results have a limitation because they were achieved in vitro, meaning there is a lack of confidence in what anthelmintic activity the plant extract has in the equine.
DeleteAnother limitation is that no up to date research has been completed to further back this information up, with this paper being completed in 2013 it is difficult to be confident in these results without more research.
DeleteAnother fungi species being investigated as a means for alternative parassite control is Duddingtonia flagrans, a nematophagous fungi, which showed, in vitro and in initial trials in vivo, promising results in reducing nematode parassitic burden and in reducing the number of parasitic nematode larvae present on pasture (Bampidis et al., 2020).
ReplyDeleteJunco et al. (2022) further reviewed the application of this fungi species finding that In vitro tests showed that the action of the fungus against infective larvae ranged from 48 to 94% whereas in vivo applications had variable results in different studies. This is mostly due to environmental conditions, dosage and frequency of administration that condition both the presence of larvae and the activity of the fungus.
Following the recomandations from literature, in order for this fungi to be used as an efficient parasite control method, regional studies must be carried out on field conditions as to assess wether the environment plays an important role on the fungi effectiveness in controlling the preparasitic forms of nematodes in different livestock species.
Overall, in response to rising anthelminitic resistance, the use of fungi and plant derivates, the use of copper oxide wire particles and condensed tannin-rich plants and grazing systemscan be effective and sustainable alternatives for parasite control in livestock, coadiuvated by a selective therapiutic use of anthelmintics (Burke & Miller, 2020)
ReplyDelete