Prevalence, risk factors, and species diversity of strongylid nematodes in domesticated Thai horses: insights from ITS-2 rDNA metabarcoding

Strongylid nematodes represent a major health and performance concern for equids globally. However, the epidemiology of strongylid infections in horse populations remains largely unexplored in Thailand. This study investigated the prevalence of strongylid parasites and the associated risk factors in domesticated horses in Thailand. Additionally, the study utilized ITS-2 rDNA metabarcoding to characterize the diversity and co-occurrence patterns of strongylid species. Of the 408 horses examined, 50.98% tested positive for strongyle infection, with an average intensity of 445.67 ± 639.58 eggs. Notably, only 25.74% exhibited fecal egg counts of ≥ 200 eggs per gram (EPG), highlighting the need for targeted deworming protocols. Significantly higher EPG values were observed in yearling horses (p = 0.001) and those kept in outdoor pastures (p = 0.0001). Metabarcoding identified 15 strongylid species, with Cylicostephanus longibursatus being the most abundant (mean relative abundance: 37.30%, SD = 31.16%). No Strongylus species were detected. Alpha diversity analysis revealed no significant differences in species richness and evenness across horse groups, while beta diversity analysis showed significant dissimilarities (p = 0.004), primarily driven by Cylicostephanus longibursatus, Cyathostomum pateratum, and Cylicostephanus calicatus, which contributed to over 60% of the variation. Species co-occurrence patterns were largely random, with a limited number of positive (n = 5) and negative (n = 2) species pair associations. These findings provide essential insights into the current state of strongylid infections in Thai horses and offer a foundation for future research and management strategies.

Chemical contaminants in donkey milk: A review of literature on sources, routes and pathways of contamination, regulatory framework, health risks, and preventive measures

Donkey milk has garnered increasing attention due to its potential health benefits and nutritional properties, positioning it as a valuable alternative to cow's milk for specific consumer groups, such as individuals with allergies, young children, elderly populations, and those with compromised immune systems. However, the presence of chemical contaminants in donkey milk presents a significant concern for food safety and public health. This review aims to provide an assessment of the types and sources of chemical contaminants in donkey milk, including heavy metals, mycotoxins, pesticides, polychlorinated biphenyls, and antimicrobial and antiparasitic veterinary drugs. Through a comprehensive analysis of available literature, we examine the routes and pathways through which these contaminants enter the milk, their prevalence, and the associated health risks. The review also briefly discusses analytical methods for detecting these contaminants and the existing legislative framework that regulates these contaminants, underscoring its critical role in safeguarding public health and promoting safe consumption of donkey milk products. By identifying gaps in existing research and suggesting areas for further study, this review seeks to contribute to the development of more effective strategies for monitoring and mitigating chemical contamination in donkey milk, ultimately safeguarding consumer health and supporting the sustainable production of this niche dairy product.

Common clinical findings identified in working equids in low- and middle-income countries from 2005 to 2021

Despite several millions of working equids worldwide, there are few published studies regarding the epidemiology of their health and welfare. Data collected by non-governmental organisations (NGOs) operating in the working equid sphere therefore have important epidemiological value and could be used towards animal health surveillance. The aim of this study was to identify common clinical findings and mortality patterns of working equids in low- and middle-income countries and investigate their epidemiology using data collected from an international NGO. A retrospective analysis was conducted to determine the proportion of clinical findings and mortality risk by equid species, year and region. Negative binomial regression models were generated to investigate differences in mortality risk and proportion of key clinical findings between equid species, hemispheres and calendar month. A total of 4,313,606 presentations were reported from 14 countries between January 2005 and March 2021 (mean 22,121; SD ± 7,858 per month). Wounds and abscesses were the most reported clinical finding for all equid species (mean proportion 35%; SD ±0.19 of all findings). A higher proportion of wounds (mean proportion 41.7%; SD±0.2) was recorded in donkeys than mules or horses (P<0.001). Mules had higher reported mortality risk (1.2%; 95% CI 0.94-1.46%) than horses (0.4%; 95% CI 0.36-0.55%; p<0.001) or donkeys (0.2%; 95% CI 0.14-0.22%). Work-related wounds were the predominant finding in working equids, particularly so in donkeys. Prevention strategies should focus on improvements to work equipment and practices for all equids. Future investigations required include refinement of diagnostic approaches for donkeys and investigation of risk factors to understand the higher mortality in mules. Routine monitoring of clinical findings reported by national or international NGOs could be included in animal health surveillance strategies, although standardisation of data for this purpose is needed so that changes in prevalence following implementation of prevention strategies can be monitored.

BEVA primary care clinical guidelines: Equine parasite control

BACKGROUND

There is a lack of consensus on how best to balance our need to minimise the risk of parasite-associated disease in the individual horse, with the need to limit the use of anthelmintics in the population to preserve their efficacy through delaying further development of resistance.

OBJECTIVES

To develop evidence-based guidelines utilising a modified GRADE framework.

METHODS

A panel of veterinary scientists with relevant expertise and experience was convened. Relevant research questions were identified and developed with associated search terms being defined. Evidence in the veterinary literature was evaluated using the GRADE evidence-to-decision framework. Literature searches were performed utilising CAB abstracts and PubMed. Where there was insufficient evidence to answer the research question the panel developed practical guidance based on their collective knowledge and experience.

RESULTS

Search results are presented, and recommendation or practical guidance were made in response to 37 clinically relevant questions relating to the use of anthelmintics in horses.

MAIN LIMITATIONS

There was insufficient evidence to answer many of the questions with any degree of certainty and practical guidance frequently had to be based upon extrapolation of relevant information and the panel members' collective experience and opinions.

CONCLUSIONS

Equine parasite control practices and current recommendations have a weak evidence base. These guidelines highlight changes in equine parasite control that should be considered to reduce the threat of parasite-associated disease and delay the development of further anthelmintic resistance.

CANTERing towards more sustainable helminth control

Victoria Colgate of Equine Infectious Disease Surveillance introduces CANTER, a voluntary pan-industry initiative that is aiming to inspire behaviour change among horse owners and promote a more sustainable approach to controlling parasites in their animals.

Epidemiology of Colic: Current Knowledge and Future Directions

Epidemiologic studies are essential for the generation of evidence-based, preventive health care strategies. This includes ways to minimize colic risk and assist informed decision making concerning diagnosis, treatment, and likely outcomes. It is important to consider that colic is not a simple "disease" but is a syndrome of abdominal pain that encompasses multiple different disease processes, and which is multifactorial in nature. This review focuses on prevention and diagnosis of colic, including specific forms of colic, communications with owners/carers concerning colic risk and management, and areas of future research.

Equine Anthelmintic Resistance: Horse Owner and Yard Manager Perception of the Barriers Affecting Strategic Control Measures in England

Equine anthelmintic resistance poses a threat to the health and welfare of horses worldwide. With no new imminent anthelmintic classes, it is vital to decrease the resistance rate and preserve available classes. Traditional indiscriminate anthelmintic use is not synonymous with a strategic control ideology; however, many continue to implement outdated practices. In comparison to livestock farmers, there have been few social science studies examining horse owner behaviours. This study aimed to understand the perceived barriers faced by horse owners and yard managers to adopting a strategic approach to helminth control, and to explore their experiences. Semi-structured interviews permitted the exploration of the stakeholders' beliefs, opinions, experiences, attitudes, and behaviours. Personal resources, internal influences, and external influences were identified by participants as the barriers to adoption of strategic controls. Two further themes impacting effective implementation of strategic controls emerged surrounding helminth information and source, as well as accurate dosing. Challenges associated with anthelmintic administration and bodyweight estimation suggest that inaccurate dosing is prevalent. Industry-wide implementation of a single 'best practice' could support prescriber decision-making to encourage uptake of effective strategic helminth controls. The barriers identified in this study could help influence guidance given to horse owners through a better understanding of their beliefs and behaviours.

Comparison of FECPAKG2, a modified Mini-FLOTAC technique and combined sedimentation and flotation for the coproscopic examination of helminth eggs in horses

Background

Due to high prevalence of anthelmintic resistance in equine helminths, selective treatment is increasingly promoted and in some countries a positive infection diagnosis is mandatory before treatment. Selective treatment is typically recommended when the number of worm eggs per gram faeces (epg) exceeds a particular threshold. In the present study we compared the semi-quantitative sedimentation/flotation method with the quantitative methods Mini-FLOTAC and FECPAK^G2 in terms of precision, sensitivity, inter-rater reliability and correlation of worm egg counts to improve the choice of optimal diagnostic tools.

Methods

Using sedimentation/flotation (counting raw egg numbers up to 200), we investigated 1067 horse faecal samples using a modified Mini-FLOTAC approach (multiplication factor of 5 to calculate epgs from raw egg counts) and FECPAK^G2 (multiplication factor of 45).

Results

Five independent analyses of the same faecal sample with all three methods revealed that variance was highest for the sedimentation/flotation method while there were no significant differences between methods regarding the coefficient of variance. Sedimentation/flotation detected the highest number of samples positive for strongyle and Parascaris spp. eggs, followed by Mini-FLOTAC and FECPAK^G2. Regarding Anoplocephalidae, no significant difference in frequency of positive samples was observed between Mini-FLOTAC and sedimentation/flotation. Cohen’s κ values comparing individual methods with the combined result of all three methods revealed almost perfect agreement (κ ≥ 0.94) for sedimentation/flotation and strong agreement for Mini-FLOTAC (κ ≥ 0.83) for strongyles and Parascaris spp. For FECPAK^G2, moderate and weak agreements were found for the detection of strongyle (κ = 0.62) and Parascaris (κ = 0.51) eggs, respectively. Despite higher sensitivity, the Mini-FLOTAC mean epg was significantly lower than that with FECPAK^G2 due to samples with > 200 raw egg counts by sedimentation/flotation, while in samples with lower egg shedding epgs were higher with Mini-FLOTAC than with FECPAK^G2.

Conclusions

For the simple detection of parasite eggs, for example, to treat foals infected with Parascaris spp., sedimentation/flotation is sufficient and more sensitive than the other two quantitative investigared in this study. Mini-FLOTAC is predicted to deliver more precise results in faecal egg count reduction tests due to higher raw egg counts. Finally, to identify animals with a strongyle epg above a certain threshold for treatment, FECPAK^G2 delivered results comparable to Mini-FLOTAC.

Grpahical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-022-05266-y.

An Exploration of Environmentally Sustainable Practices Associated with Alternative Grazing Management System Use for Horses, Ponies, Donkeys and Mules in the UK

Simple Summary

Equestrian land could be a potentially important environmental resource, given that pastureland can help to sequester carbon from the atmosphere, prevent soil erosion and provide diverse ecosystems for native plant and wildlife species. However, equestrian land has been overlooked in environmental research and policy. This study reports on the ways which horse, pony, donkey and mule keepers in the UK described environmental practices as part of their equid care. Through an analysis of survey responses (N = 758) from equid keepers using alternative grazing systems, we report on three very different management approaches which resulted in keepers aiming to promote healthy pastures and healthy animals. This study provides the basis for future research exploring attitudes to sustainability in equid keepers, as well as evaluating the impact of their efforts.

Abstract

Equestrian grazing management is a poorly researched area, despite potentially significant environmental impacts. This study explored keepers’ use of alternative grazing systems in the care of UK horses, donkeys and mules through an internet survey. The survey was available during the summer of 2020 and comprised closed and open questions, which were analysed with descriptive statistics and iterative thematic analysis, respectively. A total of 758 responses was incorporated into the analysis; the most popular system used were tracks (56.5%), Equicentral (19%), “other” (e.g., non-grass turnout) (12.5%), rewilding (7.5%) and turnout on either moorland (0.7%) or woodland (2.5%). The thematic analysis highlighted that equid keepers across the systems were highly engaged in exploring sustainable practices. Their approaches varied according to each system, yet all aimed to fulfil practices in three major categories, i.e., supporting diverse plant life (usually through restricting equid access to certain areas), supporting wildlife (through the creation of biodiverse environments) and sustainably managing droppings and helminths. Additionally, proponents of the Equicentral systems declared to be aiming to support soil health. These data provide a promising insight into equid keepers’ behaviour and attitudes to sustainability.

Using worm egg count data to detect and counter trends in equine helminth abundance

Jan van Dijk, RCVS specialist in veterinary parasitology, describes how data can be used to both increase understanding of trends in equine helminth abundance and drive better treatment of individual horses.

Study design synopsis: Battle in the stable: Bayesianism versus Frequentism

Frequentism dominates scientific practice although Bayesianism may provide an alternative, especially when analysing data from complex, high-dimensional models. The key differences between Bayesianism and Frequentism are highlighted in the introduction. Next, I review the different stages of Bayesian statistical reasoning in a research setting, explain the key concepts and illustrate them with toy examples taken in equine veterinary medicine. An extension to more complex models (Bayes network) is introduced and guidelines are offered as a conclusion.

Monitoring equine ascarid and cyathostomin parasites: Evaluating health parameters under different treatment regimens

BACKGROUND

Strongylid and ascarid parasites are omnipresent in equine stud farms, and ever-increasing levels of anthelmintic resistance are challenging the industry with finding more sustainable and yet effective parasite control programs.

OBJECTIVES

To evaluate egg count levels, bodyweight and equine health under defined parasite control protocols in foals and mares at two Standardbred and two Thoroughbred stud farms.

STUDY DESIGN

Longitudinal randomised field trial.

METHODS

A total of 93 foals were enrolled and split into two treatment groups, and 99 mares were enrolled and assigned to three treatment groups. All horses underwent a health examination, and episodes of colic or diarrhoea were recorded at each faecal collection date. Bodyweights were assessed using a weight tape, and mares were body condition scored. Group A foals (FA) were dewormed at 2 and 5 months of age with a fenbendazole/ivermectin/praziquantel product, while group B foals (FB) were dewormed on a monthly basis, alternating between the above-mentioned product and an oxfendazole/pyrantel embonate product. Group A mares (MA) were dewormed twice with fenbendazole/ivermectin/praziquantel, group B mares (MB) were dewormed with the same product, when egg counts exceeded 300 strongylid eggs per gram, and group C mares (MC) were dewormed every 2 months, alternating between the two products. Health data were collected monthly for 6 months (foals) and bimonthly for 13 months (mares). Data were analysed with mixed linear models and interpreted at the α = 0.05 significance level.

RESULTS

There were no significant bodyweight differences between foal groups, but MA mares were significantly lighter than the other two groups. Very few health incidents were recorded. Foals in group FA had significantly higher ascarid and strongylid egg counts, whereas no significant differences were observed between mare groups.

MAIN LIMITATIONS

Study duration limited to one season.

CONCLUSIONS

Anthelmintic treatment intensity was lowered from the traditional intensive regimes without measurable negative health consequences for mares and foals.

Novel Equine Faecal Egg Diagnostics: Validation of the FECPAKG2

Simple Summary

Faecal egg counts (FECs) are the standard method of diagnosing the level of intestinal parasites in horses and other grazing animals. Testing before treatment is an important factor in slowing the appearance of drug resistance in these parasites. The FECPAK^G2, optimised for livestock, allows owners to perform FECs by tapping into remote expertise. However, the performance of the FECPAK^G2 has yet to be assessed for equids. Therefore, a comparison of the FECPAK^G2(G2) method with an accepted non-remote equine FEC method (FECPAK^G1) was performed, using samples of faeces from horses in Wales and New Zealand. The FECPAK^G2 performed equally as well as the control method (FECPAK^G1), and this was true regardless of the data’s country of origin. 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 FECPAK^G2 method is suitable for performing FECs in horses. It is anticipated that the user-friendliness of the method will increase the uptake of FECs amongst horse owners by the direct use of the technology or through their veterinary practice, likely slowing the development of anthelmintic resistance.

Abstract

Faecal egg counts (FECs) are the standard method of diagnosing the level of parasitic helminth egg shedding in horses and other grazing animals. Testing before treatment is an important factor in slowing the appearance of anthelmintic resistance in nematode parasites. The FECPAK^G2, optimised for livestock, is reported to allow owners to perform FECs on their own animals without the need for a separate microscope or any specialist knowledge by tapping into remote expertise. However, the performance of the FECPAK^G2 has yet to be assessed for equids. Therefore, a comparison of the FECPAK^G2 (G2) method with an accepted equine FEC method (FECPAK^G1(G1)) was performed, using faecal samples from 57 horses in Wales and 22 horses in New Zealand. There was a significant correlation between the FECs obtained by the two methods (p < 0.001) and no effect of the country of origin on the data (p = 0.157). The mean percentage accuracy compared to the control values (mean G2 count as a percentage of the mean G1 count, ±SStandard Error (SE)) was 101 ± 4%. There was no significant interaction between the method applied and the country of origin of the data (p = 0.814). The relative accuracy of the G2 method compared to the control method (FECPAK^G1) was not affected by the level of infection (p = 0.124) and it was concluded that the FECPAK^G2 method is a suitable method of performing FECs in horses. It is anticipated that the user-friendliness of the method will increase the uptake of FECs amongst horse owners, either by the direct use of the technology or through their veterinary practice, likely slowing the development of anthelmintic resistance.