Cyathostomin resistance to moxidectin and combinations of anthelmintics in Australian horses

Background Cyathostomins are the most important and common parasitic nematodes of horses, with > 50 species known to occur worldwide. The frequent and indiscriminate use of anthelmintics has resulted in the development of anthelmintic resistance (AR) in horse nematodes. In this study we assessed the efficacy of commonly used anthelmintics against cyathostomins in Australian thoroughbred horses. Methods Two drug efficacy trials per farm were conducted on two thoroughbred horse farms in the state of Victoria, Australia. In the first trial, the horses on Farm A were treated with single and combinations of anthelmintics, including oxfendazole (OFZ), abamectin (ABM), abamectin and morantel (ABM + MOR), moxidectin (MOX) and oxfendazole and pyrantel (OFZ + PYR), at the recommended doses, whereas the horses on Farm B only received MOX, at the recommended dose. The faecal egg count reduction test (FECRT) was used to determine the efficacy and egg reappearance period (ERP) of anthelmintics. Based on the results of the first trial, the efficacies of MOX and a combination of ABM + MOR were reassessed to confirm their activities against cyathostomins. Results Of the five anthelmintic products tested on Farm A, resistance against OFZ, ABM and OFZ + PYR was found, with efficacies of − 41% (− 195% lower confidence limit [LCL]), 73% (60% LCL) and 82% (66% LCL) at 2 weeks post-treatment, respectively. The FECRT showed high efficacies of MOX and ABM + MOR (100%) at 2 week post-treatment and shortened ERPs for these anthelmintics (ABM + MOR: 4 weeks; MOX: 5 weeks). Resistance to MOX was found on Farm B, with a reduced efficacy of 90% (70% LCL) and 89% (82% LCL) at 2 weeks post-treatment in trials one and two, respectively. Conclusions This study provides the first evidence of MOX- and multidrug-resistant (ABM and combinations of anthelmintics) cyathostomins in Australia and indicates the need for continuous surveillance of the efficacy of currently effective anthelmintics and large-scale investigations to assess the ERP for various anthelmintics. Graphical Abstract

Genetic inbreeding depression load for fertility traits in Pura Raza Española mares

Fertility is a key factor in the economic success of horse farms. However, it has received little attention due to the difficulty of measuring fertility objectively. Since its studbook creation (1912), the Pura Raza Española (PRE) breed has been a closed population and become high in-bred resulting in inbreeding depression (poor phenotypic values). Nevertheless, heterogeneous effects of inbreeding depression have been detected among founders and non-founders. The aims of this study were (1) to analyse the genetic parameters for reproductive traits in mares of the PRE horse breed, and (2) to estimate, for the first time, the inbreeding depression load associated with common ancestors of the breed. A total of 22,799 mares were analysed. Heritability estimates ranged from 0.05 (interval between first and second foaling) to 0.16 (age at first foaling), while inbreeding depression load ratios ranged from 0.06 (parturition efficiency at 6 th foaling) to 0.17 (age at first foaling), for a partial inbreeding coefficient of 10%. While heritability is related to the variability expressed in the population, inbreeding depression load ratios measure the potential variability, whether expressed in the population or not. Most correlations between additive and inbreeding depression load genetic values were significant (P-values <0.001), and of low to moderate magnitude. Our results confirm that individual inbreeding depression loads allow us to select horses that have a genetic value resistant to the deleterious effects of inbreeding.

Improving Horse Welfare and Environmental Sustainability in Horse Husbandry: Linkage between Turnout and Nitrogen Surplus

A scientific consultation tool is currently being developed in Germany to assess, analyze, and improve animal welfare on site and simultaneously consider aspects of environmental sustainability in horse husbandry in order to contribute to a resource-conserving and responsible handling of natural resources and the welfare of living beings. To date, no study has assessed to what extent species-appropriate free-range locomotion possibilities are implemented on horse farms and to what extent turnout areas are affected by unwanted nutrient inputs from horse excretions. Using the indicators “species-appropriate turnout” (hereafter: “turnout”) and “unwanted nitrogen inputs in water bodies” (based on “nitrogen surplus”), we exemplarily examine animal- and environmentally relevant aspects of horse husbandry. We conducted 88 assessments on 46 horse farms (n = 2220 horses) to test literature-based indicators of animal welfare and environmental sustainability. We found that the indicator “nitrogen surplus,” used to assess an aspect of environmental sustainability, was mostly a problem in the wintertime (summertime = −4.24, range: −109.27–58.97; wintertime: mean: 12.01, range: −35.19–468.00 nitrogen surplus per hectare, n = 44 farms, p < 0.001), when the horses had a reduced space allowance for free locomotion. On most farms, “turnout” was provided daily for several hours, but in many of the single housing systems, not all horses had the possibility for free locomotion (24.1 ± 20.4% of horses per farm), which is unacceptable in terms of animal welfare. Husbandry systems with a large enough space allowance for turnout (≥200 m2 per horse) were found to be measures with a valuable synergetic effect, providing a resource which is an opportunity both for an environmentally sustainable and welfare-friendly horse husbandry. Demanuring remarkably decreased the nitrogen surplus (p < 0.001). Hence, based on the study, we recommend to daily demanure the pasture or paddock if the space allowance is less than 200 m2 per horse. In conclusion, regarding animal welfare, group housing is favorable, but regarding a site-specific environmentally friendly or even biodiversity-enhancing management, space allowance per horse is a crucial factor rather than the type of housing system. The two selected exemplary indictors demonstrate the need for a holistic and comprehensive decision support system that considers the linkage between horse welfare and environmental sustainability in order to assist peoples’ decision-making with horses under their care.

Welfare problems of horses

The article presents an analysis of the basic concepts of animal welfare, which is a prerequisite for quality and successful innovative animal husbandry. The horses welfare should be considered from the standpoint of the concept of the "five freedoms", which should be reflected in the lives of animals. The aim of the article is to analyze the state of the horses welfare and the prospects of development and implementation at the national and European levels. The analysis indicates the need to develop a system for assessing the welfare of horses and its implementation in Ukraine, while, taking into account objective and subjective indicators, the system for assessing the welfare of horses should include owners, veterinarians (horse care) and experts. To assess the welfare of sport horses, the Veterinary Regulations (BP) of the International Equestrian Federation (FEI) must be used during the competition, which must be observed during the event. Methods for assessing the degree of welfare, characterize the condition of the animal in both external and internal indicators, but the dominant is stress, which through the nervous and endocrine systems adversely affect all parts of the immune system. In Ukraine, the horse population has tripled reduce in thirty years and continues to decline, but the analysis of horse welfare in Ukraine is either not conducted at all, or is sporadic and mainly aimed at assessing individual animal health indicators (assessment of body condition, lameness, etc.). Therefore, in Ukraine it is necessary to establish criteria and develop a system for assessing the welfare of horses, improving the legal framework and implementation in practice. A plan of recommended action for stakeholders (federations, veterinarians, horse owners, government services, etc.) was presented, and it was recommended to develop and implement criteria for assessing the welfare of horses that could be used to study animal welfare. We believe that the system of horse welfare assessment as a consulting tool is necessary for the standardization of survey and analysis of welfare, to develop measures to optimize the management of horses, which should be the main document of equestrian associations of Ukraine. In addition, legislation on the welfare of horses is crucial, but there is no legislation acts in the field of welfare. Undoubtedly, in combination with the welfare of horses, it is important to develop an algorithm for biosecurity in the horses management with an emphasis on the epizootology of diseases, vaccination conditions, disinfection and analysis of critical points of admission to animals, which should be the basis for the development of the National Standard for Welfare and Biosecurity at the level of horse farms in Ukraine.

Anthelmintic resistance of horse strongyle nematodes to ivermectin and pyrantel in Lithuania

Background With intensive use of anthelmintic drugs in recent decades, anthelmintic resistance (AR) in horse nematodes is becoming a growing issue in many countries. However, there is little available information about the parasites, treatment practices or AR in the horse population in Lithuania. The aim of this study was to assess the current situation of AR on horse farms in Lithuania. The study was conducted in 25 stables on horses with a strongyle faecal egg count (FEC) of ≥ 200 eggs per gram. A faecal egg count reduction test (FECRT) was performed on each farm after administration of ivermectin (IVM) or pyrantel (PYR). Results The efficacy of IVM was comparatively high, with 98.8% of 250 horses having a zero egg count 14 days after treatment. Two conditions were used to interpret the FECRT results for PYR: firstly, resistance was determined when FECR was < 90% and the lower 95% confidence interval (LCL) was < 80%, and secondly when in addition the upper confidence level (UCL) was < 95%. Under the first condition, resistance against PYR was found in five stables (25% of all tested herds), while when considering the UCL as well, resistance was only detected in two stables (8%). The FEC showed a significant (P < 0.01) difference between the treatment and control groups. Only cyathostomin larvae were detected in larval cultures derived from strongyle-positive faecal samples collected 14 days after treatment of a test group with PYR. Conclusions This in vivo study showed that PYR resistance is prevalent on horse farms in Lithuania, while the efficacy of IVM still appears to be unaffected. However, further studies of ivermectin resistance are needed. These findings should guide the implementation of more sustainable management of strongyle infections in horses in Lithuania.

The Role of Socio-Economic Determinants of Horse Farms for Grassland Management, Vegetation Composition and Ecological Value

Socio-economic context is increasingly seen as a decisive factor for sustainable agricultural land use. The high prevalence of part-time farming and frequent lack of formal agricultural education within the equine sector are often seen as reasons why horse-grazed pastures do not fulfill their biodiversity potential. In spite of the substantial variability within horse farming, little is known about the relationship of socio-economic determinants with vegetation characteristics of horse-grazed grasslands. We surveyed 122 horse farms in Germany, classifying them into four socio-economic classes according to farm income type and farm managers’ agricultural education. We recorded farm structure parameters, grassland management practices and vegetation characteristics. Socio-economic class partly explained the great variability in farm structure that we observed. In contrast to our expectation, income type and agricultural education did not distinctly affect grassland management and were neither directly nor indirectly related to vegetation characteristics. Part-time farming and lack of agricultural education thus did not adversely affect the ecological value of horse-grazed grasslands. By contrast, both farm structure and paddock level management affected grassland vegetation and ecological value. Therefore, the socio-economic context of horse farms should be addressed in further research with strategies targeting the development of sustainable grassland management in horse keeping.