Seasonal Variation in Habitat Selection by Free-Ranging Feral Horses Within Alberta’s Forest Reserve

Little is known about habitat selection by free-ranging feral horses in Montane environments, including how horse use may vary seasonally throughout the year. We tracked four global positioning system collared horses in four separate harems between November 2008 and October 2010 for a portion of the Rocky Mountain Forest Reserve in southwest Alberta, Canada. We assessed seasonal habitat selection for the study period by combining locational data with landscape data (including vegetation types) in an information theoretic framework. Home ranges for horses varied from 12.4 to 90 km² and were confined to local watersheds. Horses selected most for lowland grasslands across all seasons, with shrublands increasingly selected in spring and summer. Harvested conifer forests were only selected by horses during winter. Resource selection functions indicated that in addition to vegetation type, horses were selecting for a variety of habitat characteristics (i.e., distance to forest and solar radiation), while water availability, topographic accessibility, and disturbance features (e.g., distance to roads, recreational trails, and seismic lines associated with energy exploration) had little or no influence on horse selection. Overall, horses demonstrated selection for habitats covering 14% of the study area while avoiding 42% of habitats: remaining areas were used in proportion to their availability. Concentration of horse use within sparse vegetation types (grassland and shrubland), particularly during one or more times of the year, help identify critical horse habitat including areas where multiple, overlapping land uses interact on public land.     

Potential Spread of Cheatgrass and Other Invasive Species by Feral Horses in Western Colorado

The invasive grass cheatgrass (Bromus tectorum L.) presents major challenges for land management and habitat conservation in the western United States. Feral horses (Equus ferus caballus) have become overabundant in some areas of the West and can impact fragile semiarid ecosystems. Amid ongoing efforts to control cheatgrass in the Great Basin, we conducted a study to determine if feral horses contribute to the spread of cheatgrass through distribution via their feces. We collected feral horse fecal samples from Little Book Cliffs Herd Management Area in western Colorado in 2014. Fecal samples were dried, and 20 from each of 3 collection sessions were cultivated to examine germination success. Six species germinated from 18 samples (30%; mostly one plant per sample where germination occurred), including cheatgrass from 8% of samples. In a separate study we examined the diet of this same horse population using fecal plant DNA barcoding. Plant species that germinated were rare in the diet and germinated from fewer samples than expected relative to their detection in the diet. Our results suggest that feral horses could be contributing to cheatgrass propagation. Native ungulates and domestic cattle also have this potential. Although management of all large ungulates is necessary to mitigate cheatgrass spread, control of feral horse numbers is particularly necessary.     

A survey on the use of rugs in Australian horses

The practice of horse rugging has important implications for horse welfare and performance, but in Australia, rugging practices have not been properly documented. The objective of this study was to obtain an understanding of Australian horse rugging practices. An online survey reviewed the management of 2659 Australian horses over 12 months. Of the reported horses a total of 84.8% were rugged, although most owners (69.5%) indicated that they were unsure whether horses needed to be rugged at all. Rugging was felt by 59.8% of owners to be a requirement for horses in competition. Riding and competition were significantly associated with the use of rugs. Nearly all respondents (89.0%) felt that ‘over-rugging’ was a concern. However, 4.8% of owners would use up to 4 rugs at any one time on their horse and 21.4% of horses were still rugged in temperatures above 20°C in Australia. Many Australian horse owners (42.8%) also believe that horses feel cold if they are not rugged. Anthropomorphism when it comes to rugging horses cannot be justified as the horse has a much wider thermoneutral zone (TNZ) than humans. Australian climate, owner opinions, equestrian discipline and whether a horse is used for riding influence Australian horse rugging practices. However, current practices are based on limited available research and are not necessarily to the benefit of the horse. The major limitation was that the survey likely attracted respondents who are interested in the topic creating a self-selection bias.     

Epizootiological aspects of type 1 and type 4 equine herpesvirus infections among horse populations.

The dissemination of equine herpesvirus types 1 (EHV-1) and 4 (EHV-4) among various horse populations in Japan was investigated through the isolation and typing of virus strains from horses with respiratory diseases. Type specific monoclonal antibody pools were used for the typing of isolates. The 42 strains of EHV-1 and 64 strains of EHV-4 were isolated from 4593 nasal swabs and/or blood plasma samples collected from 3326 horses during a period from 1979 to 1990. All the strains of EHV-1 were isolated from racehorses only and during the winter season exclusively, when the epizootic of respiratory diseases occurred among racehorse populations at two Training Centers of the Japan Racing Association. In contrast, the strains of EHV-4 were isolated from horses irrespective of the season, facility, or horse population; foals and yearlings in breeding farms and our institute, rearing horses in rearing farms, and racehorses. Especially, 4 strains of EHV-4 were isolated from plasma samples containing buffy coat cells. We believe this is the first reported case of EHV-4 cell-associated viremia in the world. All 87 strains isolated from aborted fetuses were identified as EHV-1. The results suggest that EHV-1 is responsible for epizootic respiratory diseases in racehorses in the winter and abortion among mares at the late stage of gestation, and that EHV-4 causes respiratory diseases throughout the year among all horse populations.     

Anthelmintic resistance in equine parasites - detection, potential clinical relevance and implications for control

During the past two decades anthelmintic resistance in equine parasites has been found in the group of small strongyle species (cyathostomins) and in the ascarid species Parascaris equorum. The ubiquitous nature and possible severe consequences of disease with these nematodes make them the prime targets of current worm control programmes. Traditional control strategies mainly rely on the strategic application of anthelmintics, currently represented by three major drug classes: benzimidazoles (BZ), the tetrahydropyrimidine pyrantel (PYR) and macrocyclic lactones (ML). Following decades of routine and frequent anthelmintic applications, many cyathostomin populations on horse farms in industrialised countries must be considered as resistant to BZ anthelmintics. However, to date no published cases of cyathostomin disease specifically associated with anthelmintic resistance were reported. Possibly this is due to the generally subclinical and unspecific symptoms associated with cyathostomin infections. Nevertheless, exclusive reliance on the ML drug class may increase the threat of clinical disease due to drug-resistant cyathostomins. More recently, P. equorum has been reported as having developed resistance against ivermectin and moxidectin, two representatives of the ML-class. These anthelmintics are currently the most frequently used drug class in horses. This nematode species is mainly found in foals and in younger horses due to the development of immunity following exposure to infection. Infection with P. equorum can result in clinically drastic consequences such as obstruction and/or penetration of the small intestine, the latter usually leading to death. In conclusion, on horse farms the efficacy of anthelmintic treatments should be examined routinely for each drug class. Several factors can influence the rate at which anthelmintic resistance develops; high frequency of treatment being one of the most important. Modern control strategies should therefore attempt to significantly reduce anthelmintic treatments. Several pasture and farm management practices found to be negatively associated with nematode and anthelmintic resistance prevalence will be discussed in the review presented here.     

Use of matrix population models to estimate the efficacy of euthanasia versus trap-neuter-return for management of free-roaming cats

OBJECTIVE: To evaluate the efficacy of trap-neuter-return and trap-euthanatize management strategies for controlling urban free-roaming cat populations by use of matrix population models. DESIGN: Prospective study. SAMPLE POPULATION: Estimates of free-roaming cat populations in urban environments. PROCEDURE: Data from the literature describing the biology of free-roaming cat populations in urban environments were gathered. A matrix population model was developed with a range of high and low survival and fecundity values and all combinations of those values. The response of population growth rate to a range of management actions was assessed with an elasticity analysis. RESULTS: All possible combinations of survival and fecundity values of free-roaming cats led to predictions of rapid, exponential population growth. The model predicted effective cat population control by use of annual euthanasia of > or = 50% of the population or by annual neutering of > 75% of the fertile population. Elasticity analyses revealed that the modeled population was most susceptible to control through euthanasia. CONCLUSIONS AND CLINICAL RELEVANCE: Free-roaming cat populations have a high intrinsic growth rate, and euthanasia is estimated to be more effective at reducing cat populations than trap-neuter-return programs.     

Clinical trials of efficacy of praziquantel horse paste 9% against tapeworms and its safety in horses

The aim of this study with horses and a few ponies naturally infected with tapeworms was to confirm in clinical trials the efficacy and safety of a praziquantel horse paste 9%. The field trials were conducted in 1997 and 1998 in Canada, France, Germany and New Zealand. A secondary aim of the study in Canada was to determine if a 24h post-treatment fecal sample provides the best estimate of the prevalence of tapeworms in horses when using a fecal examination technique. Fecal samples were taken from each of 1062 animals at least three times pre-treatment (PRT). In Canada, fecal samples were examined using the Cornell-Wisconsin centrifugal flotation technique, and in France, Germany and New Zealand using a centrifugation/flotation technique. In each trial, the animals were randomized into two treatment groups: praziquantel horse paste 9% at 1mg/kg body weight (BW) and untreated. Fecal samples were taken from each animal nine times post-treatment and over a period of 5 weeks. In Canada, a fecal sample was taken also at 24h after treatment. Personnel examining the samples were "blinded" to treatment groups. On the day of treatment, each treated animal was examined for adverse reactions to the paste 10min after treatment and then hourly for 4h. Thereafter, each animal was examined once daily for 5 weeks. In Canada, Germany and New Zealand, the only tapeworm egg found was Anoplocephala perfoliata. In France, A. perfoliata was the most common species and a few animals had A. magna and Paranoplocephala mamillana. The prevalence of A. perfoliata among animals sampled in Canada, France, Germany and New Zealand was 51.8, 34.4, 13.1 and 26.2%, respectively. A total of 248 animals were treated with the praziquantel paste and all except one accepted it readily. There were 292 animals completing the study, 219 treated and 73 untreated. In Canada, Germany and New Zealand, the efficacy of the praziquantel horse paste 9% against A. perfoliata was 100%. In France, the efficacy against A. perfoliata, A. magna and P. mamillana was 90.9, 100 and 100%, respectively. The best estimate of prevalence for A. perfoliata in a herd was derived from fecal samples taken 24h after treatment. At 24h, 22 of 23 treated horses were positive, whereas on any day pre-treatment fewer horses were positive. Adverse reactions observed were mild to moderate colic and in only two treated horses.     

Review of hypoxaemia in anaesthetized horses: predisposing factors,consequences and management

Objective

To discuss how hypoxaemia might be harmful and why horses are particularly predisposed to developing it, to review the strategies that are used to manage hypoxaemia in anaesthetized horses, and to describe how successful these strategies are and the adverse effects associated with them.

Prevalence of behavioral disorders in the Swiss horse population

In the Swiss horse population, the prevalence of conspicuous behaviours (behavioural disorders and stable vices) was recorded with a written questionnaire in a representative survey among 1861 horse yards, and the occurrence of the stereotypic behavioural disorders crib-biting, weaving and boxwalking was analysed with emphasis on their association with horse specific (breed, age, sex) and environmental factors (e.g. housing system, nutrition, management and utilisation). 622 horse yards with a total number of 2536 horses answered to the questionnaire, and conspicuous behaviours were described for 418 horses (16.5%). Thereof, the most common stereotypic behavioural disorders with a potential negative impact on animal welfare, crib-biting, weaving, and/or boxwalking were named for 89 horses (3.5%). Stable vices (e.g. shying, bucking, aggressivity against humans) were noted for 47 horses (1.9%). For 281 horses (11.1%) conspicuous behaviours such as pawing, lip-liking, head shacking, kicking stall were given; these can be categorised as behavioural disorders or as stable vices depending on their intensity and causation. Data analysis data revealed a number of statistically significant associations between genetic factors (breed), housing, management practices, utilisation and the three stereotypies. The strongest influence on the degree of behavioural disorders had the breed as well as the extent of direct social contact with other horses, free movement on pasture, feeding pattern and regular utilisation.     

A survey of aged horses in Queensland, Australia. Part 1: management and preventive health care

Objective To describe management practices and routine preventive care of aged horses in Queensland, Australia, including effects of owner characteristics, affiliation to an equestrian group and retirement of the horse. Methods Owners of horses were contacted via Equestrian Australia (EA) and asked to complete a questionnaire about their aged horses (e.g. age, breed, sex and colour); their use and management, including preventive health care; and use of equine healthcare providers. Results Horses aged 15 years or greater represented one-third of the total horses owned in the population sample. The median age of the horses was 20.7 years (range 15–44 years). Basic husbandry and preventive health care varied depending on demographic region, age of the horse and its use. Affiliation with EA was associated with the breed and use of the horse, but not with management or preventive health care other than frequency of hoof care visits. Retired horses had reduced basic husbandry and preventive health care compared with non-retired horses. There was reduced preventive health care in rural compared with urban areas. The majority (61%) of horses in the current study had not been visited by a veterinarian in the previous 12 months. Conclusion Aged horses constitute a large subgroup of the Australian horse population. Although basic management is at a high level for most aged horses, it appears to be reduced following the horse's retirement and in the more rural areas. There was limited veterinary involvement in preventive healthcare strategies for aged horses, especially in rural areas.     

The wild horse controversy

Differing viewpoints regarding wild (feral) horse management have resulted in majorcontroversy for public land management. While the livestock industry has not advocated the eradication of wild horses, much of the publicity on the issue has given this misleading impression. The livestock industry has advocated wild horse management. Wild horse herds have, in some cases, presented major management conflicts for ranchers when they have been allowed to multiply to uncontrolled numbers. In many areas, wild horse management has been secondary in priority to completion of environmental impact statements. During this interim period, wild horse herds have gone without management. Livestock numbers have been regulated by management agencies in accordance with forage production. Wild horses also must be managed within the carrying capacity of the rangeland. Management plans developed and implemented jointly by all interested factions present the best viable solution to the wild horse controversy.     

Key beliefs underlying public feeding of free-roaming cats in Malaysia and management suggestions

Public feeding of free-roaming cats subsidizes their population growth, and has consequences in highly interconnected ecosystems including predation of native wildlife and alteration of their behavior and populations. Research is needed to explain, predict, and possibly curb public feeding. We conducted a theoretically informed analysis of key beliefs underlying intentions to feed free-roaming cats in Malaysia, offering new insights as well as management suggestions. Normative beliefs had the strongest associations with behavioral intentions. Management strategies should consider social influences from families and friends of those who feed free-roaming cats, especially cat owners and their significant others. Our results also suggest key behavioral beliefs regarding disadvantages of feeding free-roaming cats could be strengthened through education and other initiatives. The findings are particularly important for Malaysia, which is biodiversity-rich but has a large free-roaming cat population and a high incidence of public feeding.     

Evaluation of a risk-screening questionnaire to detect equine lung inflammation: results of a large field study

Reasons for performing study: The diagnosis of equine recurrent airway obstruction (RAO) and inflammatory airway disease (IAD) is based on clinical signs and increased inflammatory cell percentages in the bronchoalveolar lavage (BAL) fluid. Since a BAL is an invasive procedure, a risk‐screening questionnaire (RSQ) would be a valuable screening tool for lung inflammation. Objective: To evaluate the accuracy of a RSQ to detect lower airway inflammation (LAI) in a large population of horses. Methods: A standardised BAL was performed in the field on 167 horses in Alberta, Canada. Horses were separated into 3 categories: 1) BAL normal; 2) BAL mild to moderate LAI (MLAI), and 3) BAL severe LAI (SLAI). The horse owners were asked to complete a RSQ. The RSQ scores were compared to the BAL results to determine the likelihood of a horse having MLAI, SLAI or no LAI. Results: Based on BAL cytology, 28 (17%) horses were normal and 139 (83%) were abnormal, with 110 (66%) showing MLAI and 29 (17%) SLAI. Horses with SLAI and MLAI had a mean RSQ score of 0.95 and 0.70, respectively, compared to 0.60 for normal BAL horses. Horses with SLAI showed more clinical signs than normal and MLAI horses. The sensitivity and negative predictive values of the RSQ for detecting SLAI using a cut‐off score of 0.87, were excellent at 0.90 (95%CI 0.73–0.98) and 0.96 (95%CI 0.82–1.00). Questions on the clinical signs typically found in RAO cases differed significantly between horses with BAL SLAI and those with BAL normal. Conclusions: Prevalence of MLAI was high in this population. Although the RSQ did not allow differentiating normal horses from horses with MLAI, it has a high sensitivity to detect horses with SLAI and is therefore a good screening tool for SLAI.     

利用微卫星分析康西草原马匹种群的遗传多样性和群体结构

旨在揭示康西草原马匹的品种来源以及群体遗传结构。本研究采集了当地60匹健康状况良好、体重适中、3～6岁之间不区分公母马的血液样品,试验分为6个种群并以纯血马等4个国外马品种、1个我国地方马品种作为对照， 通过设计引物并提取基因组DNA结合微卫星扩增法对染色体上12个微卫星位点的等位基因进行检测，并对各种群遗传多样性参数、群体分化指数、瓶颈效应以及群体结构进行分析。试验按照群体个数为依据分为6组，每组1个重复，每个重复以该组样本量为标准。分析6个种群马的遗传参数结果表明，其中共检测到221个等位基因,平均Shannon指数为1.691；有效等位基因数(Ne)为3.649～5.397；期望杂合度(He)为0.681～0.798；观测杂合度(Ho)为0.632～0.780；平均多态信息含量(PIC)为0.643～0.772。这些结果表明，6个群体都具有很高的遗传多样性。通过微卫星DNA位点的连锁不平衡及哈迪-温伯格平衡分析发现， 大多数位点的P值都大于校正值(P=0.006 5)，表示较多位点都处于哈迪-温伯格及连锁平衡状态。各群体间群体分化系数(Fst)表明，群体间分化程度较低(Fst<0.15)。基于Nei’s遗传距离与地理距离之间Mantel相关性检验显示二者之间呈现正相关性(R=0.502)，但未达到显著水平(P=0.310)；各马匹种群瓶颈效应分析表明，P值极显著(P_(IAM)<0.01)说明该地区的马群体受到过瓶颈效应的影响且该马群体历史上数量有大规模的减少。通过 FCA因子分析、基于Nei’s标准遗传距离UPGMA树状图以及Structure贝叶斯聚类分析发现，该地区马种群与纯血马和温血马聚为一类，说明该种群最有可能主要来源于温血马和纯血马。这些结果揭示，康西草原地区马匹具有较高的遗传多样性，该地马群体的血统与纯血马和温血马相近，这为当地马遗传资源评估以及开发利用打下了坚实的基础。     

Is cloning horses ethical?

This paper assesses whether cloning horses is ethical by reviewing ethical arguments against cloning of nonequine species and determining whether they apply to horses, analysing ethical arguments about horse cloning which do not apply to noncompetitive species and considering the ethical dilemmas faced by veterinarians involved in horse cloning. The author concludes that concerns about the health and welfare of cloned horses render the technique ethically problematic and that the onus is on those providing commercial equine cloning services to collate data and provide a stronger evidence base for ethical decision‐making.     

The epidemiology of Thoroughbred racehorse injuries

Musculoskeletal injuries have a huge, adverse effect on the Thoroughbred racehorse industry. Although fatal musculoskeletal injuries have a low prevalence, many lameness conditions have a high prevalence. Many of the common lameness conditions in racehorses occur over weeks to months, giving ample time to intervene. Injuries may be prevented by including management practices to minimize low hoof heel angle, incorporation of more frequent, shorter high speed works or races in exercise regimes, avoiding excessive accumulation of high speed distances over short periods of time, recognizing and rehabilitating horses with mild injuries and avoiding the use of high toe grabs. It appears important to achieve uniformity of racing surfaces and for the spectrum of environmental conditions “seen” by the horse’s musculoskeletal system. Key to tracking the prevalence of injuries and the success (or lack of success) of interventions is a comprehensive method to manage racehorse inventory, horse location, and horse movement.     

Owner Compliance to an Environmental Management Protocol for Severe Equine Asthma Syndrome

Severe equine asthma (SEA) syndrome is a chronic recurrent respiratory disease, common among adult horses. The disease occurs in genetically susceptible individuals after their exposure to organic dust. Thus, environmental management has proved essential in controlling airway challenge and disease exacerbation. This is a demanding process that can only be achieved through the horse owners’ cooperation. One year after initial diagnosis of SEA in a group of 39 horses, owner compliance to an environmental management protocol was evaluated. The overall compliance to the protocol was poor and the horses’ clinical health and need for pharmacological management was related to the successful implementation of the environmental recommendations provided on disease diagnosis.     

Modelling the spread of a viral infection in equine populations managed in Thoroughbred racehorse training yards

A Monte Carlo model that simulates the management life cycle of a horse population in training on a Thoroughbred flat racing yard (i.e. stable) was developed for computer implementation. Each horse was characterised by several state variables. Discrete events at the horse level were triggered stochastically to reflect uncertainty about some input assumptions and heterogeneity of the horse population in a particular yard. This mathematical model was subsequently used to mimic the spread of equine influenza (EI) within a typical yard following the introduction of one or several infectious horses. Different scenarios were simulated to demonstrate the value of strategies for preventing outbreaks of EI. Under typical UK management conditions and vaccination protocols, the model showed that EI would propagate and that the timing of vaccination in connection with the racing season and the arrival of new horses was a critical factor. The predicted outcomes (based on published characteristics of one EI vaccine) suggested that vaccination in mid-December with boosters in June and September was a viable and successful strategy in preventing the spread of EI in a training establishment.     

The selenium and vitamin E status of horses in Prince Edward Island

Serum selenium (Se), vitamin E, and resting thyroid hormone concentrations were measured in 201 horses in Prince Edward Island (PEI). Selenium concentrations were either marginal (0.0053 to 0.1200 ppm) or deficient (< 0.0053 ppm) in 79% of horses based on current reference ranges for Se in serum. Aged and young adult pleasure horses had a higher prevalence of inadequate Se concentrations compared to racehorses and broodmares (82% and 97% versus 45% and 72%, respectively). Overall, 13% of horses had inadequate (< 200 μg/dL) serum vitamin E concentrations; most of these were young pleasure horses. No horses were hypothyroid and, contrary to findings in other species, there was a positive relationship between serum thyroxine and Se concentrations (P < 0.05). We conclude that Se deficiency is widespread in PEI horse populations, especially in pleasure horses, and vitamin E deficiency is more common in young pleasure horses. Micronutrient supplementation practices employed by PEI horse owners appear inadequate to ensure sufficiency.