Older Horses Research Articles

Challenges for the veterinary profession: A grounded theory study of veterinarians' experiences of caring for older horses.

In Great Britain, owners are keeping their horses into increasingly older age, reflecting societal changes in human-animal relationships. The uptake of routine veterinary services is reported to reduce as horses age. Horse owners seek information regarding their animal's health from alternative sources before and/or following veterinary involvement. Information regarding the experiences and behaviours of veterinarians toward older horse health care provision is limited. This study sought to explore how veterinary care for the ageing horse is conceptualised and approached by veterinarians treating horses in Great Britain. Exploratory qualitative. A subset of qualitative data, collected as part of a larger study investigating how owners and veterinarians make decisions regarding the care of the older horses, was analysed using a constructivist grounded theory approach. Data included semi-structured in-depth interviews with nine veterinarians and veterinary clinical records pertaining to the horses of 13 participating owners. Veterinarians valued regular interactions with owners to optimise a horse's management, however, the timing and nature of veterinary involvement varied. The context of older age shaped decision-making and 'age-appropriate' interventions were negotiated within the context of each horse and owner. Where participants had concerns about a horse, they sought to achieve an owner's adherence to their advice while navigating the veterinarian-owner relationship. Interpersonal dimensions of veterinarian-owner interactions appeared to shape, and could challenge, veterinarians' delivery of health care services and their own sense of being a professional who cares for animals, and about people. A sample of veterinarians were recruited for this study based on horse owners' involvement. The provision of veterinary care for the older horse rests upon networks of relationships. Collaboration between the profession and owners in both the design and delivery of, veterinary health care services may better enable different types of knowledge and values to be brought together more effectively.

Anatomy of the Right and Left Ventricular Subvalvular Apparatus of the Horse (Equus caballus).

Due to the growing interest among veterinarians and the increasing market demands, the development of equine cardiology is necessary. Currently, veterinary medicine for companion animals needs to catch up to human medicine-equine medicine included. A common condition in older horses is aortic valve regurgitation resulting from fibrosis, while its more severe form occurs in younger horses or develops due to a bacterial infection. Mitral valve regurgitation, especially dangerous due to the possibility of sudden death, has a better prognosis if the horse has valve prolapse. Tricuspid valve regurgitation usually does not pose a clinical problem, although its severe cases may lead to heart failure. Some pathologies can be treated surgically, which requires excellent knowledge of anatomy. The object of this study consisted of twenty domestic horse hearts. The focus was on the normal and comparative anatomy of the left and right subvalvular apparatus. The number of muscular bellies of the papillary muscles and the type of connection of the muscles were analysed. Moreover, the height of muscle originating from the ventricle wall was determined, the morphological regularity of the papillary muscle was assessed, and the chordae tendineae originating from the papillary muscles were examined. The conducted research allowed for comparing domestic horses with different species through other studies, the authors of which described this particular aspect. Interspecies similarities which may be correlated with the evolutionary relatedness, as well as differences that could reflect adaptation to different lifestyles, environmental conditions, or metabolic requirements of the animals, have been found. This study expands the knowledge of animals' normal and comparative anatomy, and contributes to the development of veterinary surgery, internal medicine, and biology.

Međusobni utjecaj reproduktivnog statusa, dobi i osobnosti konja na ostvarivanje punog atletskog potencijala u natjecanjima u preponskom jahanju

The study analysed the results of showjumping competitions of 41 warmblood horses of varying reproductive status, age and personality. In total, 8 stallions, 18 mares, and 15 geldings were included. Horses were divided in the following age groups: young horses 4-7 years old (n=15), mature horses 8-13 years old (n=13) and older horses 14-20 years old (n=13). Horses were also divided according to dominant personality component, obtained by questionnaires: excitability (n=4), protection (n=7), sociability (n=15), curiosity (n=9), horses without a dominant personality component (n=6). Horses in this study were compared to the results of showjumping competitions of the Croatian Equestrian Federation in the past two consecutive years, considering data from 80 classes, 44 tournaments and 3280 starts. The Winter Cup (1.10-1.3) was considered the time of absence of cyclicity in mares while the Summer Cup (1.3-1.10) was considered the full season of reproductive cyclicity of mares. The aim of the study was to determine correlations between the dominant personality component, reproductive status and age of the horse in obtaining optimal results in showjumping competitions. Based on the results, the dominant personality component positively influences the horse’s success in showjumping(ranking, penalties). Excitable horses had the poorest results, especially during the reproductive season (P<0.05). Protective horses had the best results regardless of season. It is likely that determination of the dominantpersonality component could help in better selection of showjumping horses. Geldings had the least seasonal variations, while mares had significantly better results out of season (P<0.05). Stallions also had better results out of season, though the difference was not statistically significant. Recommendations include introducing methods of cycle blockage in mares to improve focus and results in all categories. Contrary to expectations, older horses (14-20 years old) obtained better results than mature horses (8-13 years old). Further research of all observed parameters on a significantly higher sample of showjumpers is required to determine whether the findings here could be applied to the complete population of warmblood horses used in showjumping competitions in Croatia and abroad.

Assessing the Peripheral Levels of the Neurotransmitters Noradrenaline, Dopamine and Serotonin and the Oxidant/Antioxidant Equilibrium in Circus Horses.

Due to the paucity of information on circus management effects on the welfare of horses, this study investigated the plasma concentrations of noradrenaline, dopamine and serotonin, known to be indices of mental status, as well as the reactive oxygen metabolites (d-Roms) and the biological antioxidant potential (BAP), likely to denote the oxidant/antioxidant equilibrium of organisms, in horses managed in different Italian circuses. For the study, 56 circus horses of different breeds and ages were enrolled and divided into six groups according to the horses' management (circus management, groups G1-G5; classic riding management representing the control group, CG). From each horse, blood samples were collected in order to assess the concentration of selected parameters. One-way ANOVA showed no differences (p > 0.05) in serotonin, dopamine, noradrenaline, d-Roms and BAP values between circus and control horses. No differences related to the breed of the horses enrolled in the study were found in the values of all investigated parameters (p > 0.05). Furthermore, neurotransmitters showed overlapping levels between the different age classes of investigated horses (p > 0.05); contrariwise, the age of the horse displayed a significant effect on BAP values, with the oldest horses (16-21 age class) exhibiting lower BAP values compared to 4-5, 6-10 and 11-15 age classes (p < 0.05), whereas the d-Roms showed similar values in horses of different age classes (p > 0.05). The results gathered in the present study suggest that the mental status of horses under circus management was not compromised; however, better attention and care in the management of older horses is advocated, as they showed a lower biological antioxidant potential than younger horses; thus, they could be more susceptible to oxidative stress.

Comparative pharmacokinetics of phenylbutazone in healthy young-adult and geriatric horses.

To evaluate the effects of aging on phenylbutazone (PBZ) disposition in older horses (≥ 25 years old) compared to young adults (4 to 10 years old) by characterizing the pharmacokinetic profile of PBZ and its active metabolite, oxyphenbutazone (OPBZ), following a 2.2-mg/kg dose, IV. We hypothesized that the disposition of PBZ will be affected by age. 16 healthy horses (8 young adults aged 4 to 10 years and 8 geriatric horses ≥ 25 years old). Horses were administered a single 2.2-mg/kg PBZ dose, IV. Plasma samples were collected at designated time points and frozen at -80 °C until assayed using liquid chromatography-tandem mass spectrometry. Pharmacokinetic analyses were performed using Phoenix WinNonlin, version 8.0 (Certara). Both clinical and pharmacokinetic data were compared between age groups using independent samples t tests, with P < .05 considered significant. Baseline characteristics did not differ between groups, with the exception of age, weight, and plasma total solids. Plasma concentrations of PBZ were best described by a two-compartment model. The maximum plasma concentration of OPBZ was reached at 5 hours for both age groups, and the metabolite-to-parent-drug area-under-the-curve ratios were approximately 20% for both groups. None of the pharmacokinetic parameters of PBZ or its metabolite, OPBZ, differed significantly between age groups. The hypothesis was rejected as there was no significant difference in PBZ disposition in young-adult horses compared to geriatric horses. Our data do not support the need for dose adjustments of PBZ in clinically healthy geriatric horses.

A Preliminary Protocol of Radiographic Image Processing for Quantifying the Severity of Equine Osteoarthritis in the Field: A Model of Bone Spavin

Osteoarthritis (OA) of the tarsal joint, also known as bone spavin, is a progressive joint disease that increases in severity with age. It is a significant cause of hind limb lameness, leading to a deterioration in the quality of life of horses, particularly in old age. In this study, the tarsal joints of 20 older horses aged 15 to 35 years were radiographically imaged and processed using the computed digital absorptiometry (CDA) method for bone mineral density (BMD) assessment. The radiological signs of bone spavin were scored on a scale ranging from normal (0) to severe OA (3), and the examined joints were grouped according to the severity of OA. The percentage of color pixels (%color pixels), representing successive steps on the scale of X-ray absorption by a density standard, differed between the steps in a BMD characteristic manner for each group. Furthermore, two examined ranges of relative density allowed for the distinction of joints affected by severe OA from other joints, while another two ranges allowed for the differentiation of joints affected by moderate and severe OA from normal joints. The proposed color annotation-assisted decomposition of radiological images based on the CDA protocol shows promise for advancing research on the quantification of radiological signs of OA. This approach could be valuable for monitoring the progression of the disease in older horses.

Athletic prognosis following arthroscopic removal of osteochondral fragments of the proximal dorsal sagittal ridge of the fetlock in Thoroughbreds intended for flat racing.

To establish racing prognosis in Thoroughbred yearlings with proximal sagittal ridge osteochondral lesions and compare them to dorsoproximal and palmar/plantar first phalanx osteochondral lesions. A total of 47 horses had proximal sagittal ridge lesions, 34 had palmar/plantar first phalanx lesions, and 115 had dorsoproximal first phalanx lesions. Retrospective case series. Medical records of Thoroughbred yearling racing prospects treated arthroscopically for fetlock osteochondral lesions were reviewed. Data were collected from a public database, including the ability to train and race, earnings, starts, wins, and placed races. Racing prognosis was analyzed and compared between three lesion locations. Of the proximal sagittal ridge group, 76.6% raced, 65.71% of the palmar/plantar first phalanx group, and 74.58% of the dorsoproximal first phalanx group. Career length was similar for all lesions. A lower number of "starts" in the group "five years old and older" was found for the dorsoproximal first phalanx group compared to the cohort with proximal sagittal ridge lesions. Mares had more "earnings" at two years old but fewer "starts" at "five years old" compared to colts and geldings. Forelimb lesions were predictive for fewer total career starts. Proximal sagittal ridge lesions had similar prognoses to dorsoproximal and palmar/plantar first phalanx lesions. In older horses, there was an increase in the number of starts for the proximal sagittal ridge group compared to the dorsoproximal first phalanx group. Mares and forelimb lesions were associated with decreased racing starts. These findings aid in prognostication for Thoroughbreds with osteochondral lesions removed arthroscopically in the fetlock joint.

The effect of solarium light therapy on selected biological and biochemical parameters of peripheral blood in young and old horses.

The aim of the study was to assess the impact of solarium light therapy on selected biological and biochemical parameters of peripheral blood in recreational horses. The study involved 10 horses divided into two groups of young (aged 5 to 7 years) and old (aged 14 to 19 years) individuals. All animals participated in light therapy sessions every other day. Blood was sampled three times during the study: before the treatment, after five light sessions, and after ten light sessions. Morphological parameters, the activity of antioxidant enzymes, TAS values, and the levels of glutathione (GSH), vitamin D3, vitamin C, and malondialdehyde (MDA) were measured in the whole blood. Light therapy contributed to an increase in MCV, HDW, MCVr, CHr and MPV indices, and simultaneously a decrease in the basophil counts, MCHC, RDW and CHCMr indices in both groups of horses (p ≤ 0.05). At the same time reticulocytes fell in older whereas white blood cells and monocytes counts expanded in younger individuals. The treatment also increased the activity of glutathione reductase (GR) and glutathione peroxidase (GPx) in young but decreased the activity of mentioned enzymes in blood plasma of old horses. The total antioxidant status (TAS) of the blood plasma rose progressively, whereas GSH levels declined in all individuals. Moreover, vitamin D3 levels did not change, whereas vitamin C levels gradually decreased during the experiment. The therapy also helped to reduce levels of MDA in the blood plasma, especially of older horses (p ≤ 0.05). In turn, GPx and GR activities as well as MDA levels significantly declined, whereas GSH levels notably elevated in erythrocytes (p ≤ 0.05). Solarium light therapy appears to have a beneficial impact on the morphological parameters and antioxidant status of blood in recreational horses in the winter season. However, the observed results could in part be attributed to the natural physiological adaptation of each individual organism to the treatment.

93 Evaluating the efficacy of anthelmintics in an upper Midwest horse herd

Abstract Cyathostomins in the gastrointestinal tract are ubiquitous in horses around the world and remain a target in parasite control programs. Resistance to anthelmintics has risen in recent years with widespread resistance to benzimidazoles and pyrantels and emerging resistance to macrocyclic lactones. Thus, investigating the efficacy of anthelmintics in different locations is important to direct future parasite control programs. This 2-yr study evaluated the efficacy of three anthelmintic drugs in a university-owned equine herd in the upper Midwest using fecal egg count reduction tests (FECRT). Additionally, the effect of age group and body condition score (BCS) on fecal egg shedding was evaluated. We hypothesized that drug resistance is present in the parasite population of this equine herd. Fecal egg counts (FEC) of strongelid eggs were determined using the McMaster method. The efficacy of anthelmintics was determined by calculating the percentage of reduction in FEC between d 0 and d 14 post-treatment. Eighteen horses of various breeds were used in the study. The horses were grouped by age (&amp;lt; 10, 10-16, and &amp;gt; 16 yr; n = 6 in each group) and BCS using the Henneke system (5.0-5.5, n = 9; 6.0-6.5., n = 6; and 7.0-8.0, n = 3). In yr 1, horses within age group were randomly assigned to anthelmintic treatment: pyrantel pamoate, fenbendazole, or ivermectin. In yr 2, all horses received ivermectin. Individual FEC were performed on the day of anthelmintic treatment (d 0) using freshly voided feces. FEC were repeated 14 d after treatment. FEC were log transformed before analysis. Efficacy of the anthelmintics were compared using a mixed model ANOVA with repeated measures (SAS 9.4). Results were considered significant when P &amp;lt; 0.05. The FECRT was greater when treated with ivermectin and pyrantel pamoate (94.8 ± 11.6 % and 96.6 ± 14.3 %, respectively) compared with fenbendazole (54.4 ± 10.8 %; P &amp;lt; 0.05). The FECRT increased from 54.4% when treated with fenbendazole to 100% when the same horses were treated with ivermectin (P &amp;lt; 0.05). Age tended to affect egg shedding in horses (P = 0.0548). Young horses (&amp;lt; 10 yr) had a greater FEC compared with older horses (&amp;gt;16 yr; P &amp;lt; 0.05) but were not different from horses aged 10 to 16 yr (P &amp;gt; 0.05). There was no effect of BCS on strongelid egg shedding in this study (P = 0.9468). These results indicate the efficacy was within the expected range with no signs of resistance to pyrantel pamoate (93.3 to 100% reduction). There was evidence of emerging resistance to ivermectin (70.4 to 100% reduction) and significant resistance to fenbendazole (0 to 71.5% reduction) in the cyathostomin population in this horse herd. The findings of this study agree with previous research demonstrating resistance to anthelmintics. These results highlight the importance of designing improved parasite control programs to limit the spread of drug resistance with the ultimate goal of improving overall health of the horse.

Career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand

Context Racing structure and focus for racehorses differs across jurisdictions and is poorly described. In New Zealand and Australia, jumps racing accounts for a small proportion of total Thoroughbred races each year, as opposed to the larger jumps-racing (National Hunt) industry with purpose-bred horses found in the UK and Ireland. Aims This study aimed to describe the career profile and pattern of racing for Thoroughbred jumps-racing horses in New Zealand. Methods Metrics from every horse with a full jumps-racing career (n = 1276, 89% geldings) between the 2005/06 and 2021/22 racing seasons (n = 40,302 starts) were examined. Descriptive statistics, box plots and heat maps were used to describe the data, by using horse age as a proxy for career progression. Key results Jumps-racing horses had a median of 17 flat starts (IQR 9–30) before their first jumps-racing start. The median career of a jumps-racing horse was 3.7 years (IQR 2.3–5.2) and 29 starts (IQR 16–44). Older horses had a decreasing number of flat-racing starts and an increasing proportion of steeplechase-racing starts. However, the majority of horses still had at least one flat-race start per calendar year, often prior to the first jumps race. Most horses had one spell each season (length 194 days, IQR 124–259), and a condensed preparation length over the winter months, with a median of 14 days (IQR 10–21) between starts. Conclusion The career pattern for jumps-racing horses in New Zealand reflects the industry retention of horses with a prior career in flat racing into a secondary jumps-racing career. Successful horses have increased focus on preparation for the winter jumps-racing season. Implications Jumps racing provides a secondary racing career for some flat-racing horses, particularly geldings. This strategy reduces wastage of horses from the industry.

Strongyle egg shedding and egg reappearance periods in horses with pituitary pars intermedia dysfunction

Pituitary pars intermedia dysfunction (PPID) is the most common endocrine disorder of older horses. Immune dysfunction in horses with PPID could increase susceptibility to infectious diseases, including strongyle infections; however, few data are available. The aim of this study was to determine if horses with PPID had increased strongyle faecal egg counts (FEC) compared with control horses, over a fourteen-week period in Victoria, Australia. Clinical signs and plasma adrenocorticotropic hormone (ACTH) concentrations were used to categorise horses into PPID (n=14) or control (n=31) groups. Faecal samples were collected for FEC determination prior to anthelmintic treatment, and fortnightly post-treatment for each horse. Generalised linear mixed modelling, using a gamma distribution, was used to compare differences between groups in the repeated measures study. The confounding variable of age was controlled for as a fixed effect. Following anthelmintic treatment, mean FEC was greater for the PPID group compared to the control group on day 56 (405 ± 756 eggs per gram [EPG] vs 40 ± 85 EPG, p=0.05) and day 70 (753 ±1598 EPG vs 82 ±141 EPG, p=0.04). There were no differences in mean FEC between groups on days 84 and 98. Cumulative FEC (day 14 to day 98) was significantly greater for the PPID horses than control horses (2118 ± 4016 EPG vs 798 ± 768 EPG, p<0.0001). Group egg reappearance period was shorter for PPID horses (day 56 post-anthelmintic treatment) compared to control horses (day 70) and 30% of the PPID horses reached a FEC threshold of >200 EPG on day 42, compared to 0% of control horses (p=0.02). These results suggest that the rate of a re-established patent infection between groups could be different due to a comprised immune response in PPID horses or differences in the host-parasite relationship regarding encysted stage larvae. However, despite differences between groups, some horses with PPID consistently had no detectable or low FEC (<200 EPG) during the study period. These findings highlight the importance of individual FEC monitoring to determine if anthelmintic treatment is required, in line with sustainable parasite management practices.

The prevalence and risk factors of dental disease found in 100 miniature horses

IntroductionDental disease is a common condition affecting horses. Its prevalence and characteristics among most of the common breeds of horses and donkeys have been investigated and described in the literature, but information about the prevalence and etiology of dental disease of miniature horses is sparse.MethodsTo determine the prevalence and characteristics of dental disease of miniature horses, we performed oral and dental radiographic examinations on 100 miniature horses. The findings of these examinations were analyzed to determine the prevalence of dental disease and its correlation to age, sex, weight, body condition score, height at the withers, head length and head width. Older horses had a higher prevalence of dental disease, diastemata and crown elongations.ResultsThe most common dental diseases detected in this population were crown elongation, oral mucosal ulceration, diastemata, class 1 malocclusion and hypodontia. Horses with a high body condition score had an increased likelihood of having a class 1 malocclusion. Horses with wider heads had a higher prevalence of dental disease and class 1 malocclusions.ConclusionFrequent oral examinations, starting at an early age, should be prioritized as a part of miniature horse preventive health care to decrease morbidity and slow progression of dental disease.

Management of the older horse

The increasing age of horses presented for veterinary care has been recognised over several decades. The increase in the percentage of horses older than 20 years of age has been attributed to improved nutrition, early recognition and management of conditions seen more frequently in the geriatric horse, and the increased willingness of owners to pursue veterinary care to maintain the comfort of their senior horses. Geriatric medicine is devoted to the management of conditions that have increasing age as a risk factor for their development. Conditions that are seen more frequently in older horses include pituitary pars intermedia dysfunction, chronic weight loss, obesity, osteoarthritis, laminitis, neoplasia and cardiovascular dysfunction. In addition, routine wellness care is essential for early recognition of age-related changes and prompt institution of appropriate care to maintain the comfort of the horse.

Influence of Horse Age on Carcass Tissue Composition and Horsemeat Quality: Exploring Nutritional and Health Benefits for Gourmets

The aim of this study was to show the influence of the age of horses currently in use in Poland on the tissue composition of carcasses and the quality of horsemeat. To conduct a detailed dissection and analysis of horsemeat quality, 12 half carcasses of foals and young horses, 14 half carcasses of adult horses, and 14 half carcasses of older horses were selected. A highly significant difference was demonstrated between the linear measurements of the carcasses of foals and young horses compared with those of adult animals. A significantly higher dressing percentage was observed in foals compared with older horses (p ≤ 0.05). Compared with the carcasses from older horses, the foal carcasses provided a significantly higher amount of meat in class I (p ≤ 0.05). Meat obtained from foal carcasses, when compared with the raw material from other age groups of animals, was characterized by a higher number of points for individual qualitative characteristics in the sensory evaluation. The physicochemical properties of horsemeat were dependent on the age of the horses. Compared with the oldest horses, foal meat was characterized by the lowest ability to bind and retain water. The significantly highest content of protein and fat was found in the meat of adult horses compared with the meat of foals. The horsemeats consumed today, compared with those from the 1980s and 1990s, are characterized by a much lower degree of fat deposition in the carcasses, and a higher dressing percentage index and carcass meatiness. This may result in a greater popularization of horsemeat, both among processors of this raw material and the consumers themselves. This can be a very important advantage, pointing to new aspects of food quantity and quality, especially for gourmets of this type of product.

Evaluation of seasonal influences on adrenocorticotropic hormone response to the thyrotropin-releasing hormone stimulation test and its accuracy for diagnosis of pituitary pars intermedia dysfunction

Pituitary pars intermedia dysfunction (PPID) is an age-related neurodegenerative disorder, affecting >20 % of older horses. There is a need for improved endocrine tests for early disease detection, and the thyrotropin-releasing hormone (TRH) stimulation test has been recommended for diagnosis of early or mild cases. However, it is currently not recommended for year-round use due to marked seasonal variability. The aims of this cohort study were to evaluate effects of month and season on adrenocorticotropic hormone (ACTH) responses to TRH stimulation and to derive monthly cut-offs for PPID diagnosis.Sixty-three horses were assigned to control (n = 17), subclinical PPID (n = 21) and clinical PPID (n = 25) groups, based on a composite reference standard that combined clinical history and examination findings with endocrine test results. TRH stimulation tests were performed monthly for a 12-month period. Circannual changes were evaluated with one- and two-way repeated-measures analysis of variance and receiver operating characteristic curve analysis was used to derive cut-off values for basal and TRH-stimulated ACTH. TRH-stimulated ACTH concentrations were lowest in February-May and highest in August-October. Specificity of both basal and 30 min post-TRH ACTH was generally higher than sensitivity, and TRH stimulation had improved diagnostic accuracy compared to basal ACTH, although its sensitivity was not significantly greater year-round. TRH stimulation tests yielded considerably more positive results than basal ACTH in the subclinical group, but few additional positive results in clinical PPID cases. There were large differences between cut-offs that maximised sensitivity or specificity for TRH-stimulated ACTH, highlighting the importance of considering clinical presentation alongside test results in diagnostic decision-making.

Strongyle faecal egg counts in Swiss horses: A retrospective analysis after the introduction of a selective treatment strategy

The standard parasite management of horses based on regular anthelmintic treatments, now practiced for decades has resulted in a worrying expansion of resistant helminth populations, which may considerably impair control on the farm level. The aim of the present study was to obtain a retrospective (year 2010 – 2016) nationwide analysis of faecal egg count (FEC) data from the Swiss adult horse population, related to horse age and geographic region. Thirteen labs provided a total of 16,387 FEC data of horses aged four to 39 years (average: 13.6 years). The annual number of performed FEC tests increased from 38 to 4,939 within the observation period. Independent of the annual sample size the yearly patterns of the FEC were very similar. Seventy-eight percent (n = 12,840) of the samples were negative and 90 % (n = 14,720) showed a FEC below 200 strongyle eggs per gram (EPG) of faeces. The annual mean strongyle FEC ranged between 60 and 88 EPG with a total mean of 75 EPG. Horses aged 4–7 years showed a significantly (p < 0.00001) higher mean FEC compared with the other age groups, differences were not significant among the older horses. Based on ZIP codes, samples were allocated by 70.0 %, 6.0 % and 0.2 % to the German-, French- and Italian-speaking regions of Switzerland, respectively. With 222 EPG the mean FEC in the French part of Switzerland was significantly higher (p < 0.05) than in the German-speaking region (60 EPG). Eggs of Parascaris spp., anoplocephalids and Strongyloides westeri were found in 0.36 %, 0.32 % and 0.01 % of the samples, respectively. Based on 3,813 questionnaire feedbacks from owners in 2017 covering a total of 12,689 horses, sixty-eight percent (n = 8,476) were dewormed without diagnosis, two percent (n = 240) were not dewormed at all, whereas for 30 % (n = 3,721) the selective anthelmintic treatment (SAT) concept was applied. The SAT implementation rate differed significantly (p < 0.0005) between regions, with 33 %, 20 % and 25 % for the German-, French- and Italian-speaking areas, respectively. The rate of horses spending 16–24 h on pasture per day was significantly higher in the French-speaking region compared to the German-speaking part of Switzerland (p < 0.0001). In addition, pasture hygiene was practiced at a significantly lower rate in the French-speaking part compared to the German- and Italian-speaking regions (both p < 0.0001). Overall, the shift towards the SAT-concept represents a very promising development with respect to mitigating the further spread of anthelmintic resistance.

Fasciola hepatica Infection in Horses in Three Governorates in Northern Egypt: Prevalence and Risk Factors

Fasciola hepatica is a trematode parasite that affects wide range of mammalian hosts including horses. There are no epidemiological data on fasciolosis in Egyptian horses. Hence, the present study aimed to evaluate the seroprevalence of F. hepatica in horses using ELISA as well as assess the associated risk factors for fasciolosis infection. A total of 400 sera samples of horses from three Egyptian governorates were examined. The overall seroprevalence rate in horses was 13% and the disease was more prevalent in Qalubia (14.17%) and Gharbia (16.67%) which are located at Nile Delta. The likelihood of having F. hepatica seropositivity was higher in mixed-breed animals and stallions (OR = 3.97, 95%CI: 1.10–14.28 and OR = 2.07, 95%CI: 1.09–3.93, respectively), and in older horses more than 10 years (OR = 5.69, 95% CI: 1.98–16.36). Horses were more likely to be seropositive with F. hepatica when kept in outdoor housing (OR= 1.53, 95%CI: 0.78–3), during autumn (OR = 3.80, 95%CI: 1.17–12.32) and in the presence of snails (OR = 2.72, 95%CI: 1.34–5.52). Therefore, the obtained data contributes to the understanding of the epidemiology of Fasciola species, assess in establishment of management programmes to reduce disease and public health risks.

Retained efficacy of ivermectin against cyathostomins in Swedish horse establishments practicing selective anthelmintic treatment

Cyathostominae are ubiquitous to grazing horses and regarded the most prevalent internal parasite in the horse. Unfortunately, decades of indiscriminate use of anthelmintic drugs have resulted in the development of resistance in cyathostomins to all currently available drug groups, the most recent being a documented lack of efficacy to the macrocyclic lactones (ML). In vivo determination of anthelmintic resistance in horses most often utilises the faecal egg count reduction test (FECRT). Further, a shortened egg reappearance period (ERP) can indicate a change in response to the applied treatment and suggest an upcoming reduction of efficacy. Although both true resistance as demonstrated by the FECRT and shorter ERPs after ML treatment have now been shown in cyathostomins worldwide, the efficacy of ML as regards to cyathostomins in Sweden is currently unknown. The aim of the present study was therefore to determine FECRTs and ERPs after ivermectin (IVM) treatment in Swedish horses. Sixteen equestrian establishments with a minimum of six horses excreting at least 150 eggs per gram faeces (EPG) at screening were selected. For each establishment, FECRTs and ERPs were determined by collecting faecal samples prior to and 14 days after IVM treatment (200 µg/kg), and thereafter at weekly intervals for a total of eight weeks. All participants responded to a questionnaire detailing pasture management methods and anthelmintic routines.Questionnaire results showed that the majority of establishments (69%) only treated horses with anthelmintic drugs if indicated by faecal diagnostics and all of the establishments had a mean FECRT exceeding 99.0% and ERPs ranging from six to over eight weeks. The ERP was shown to increase with age as young individuals were shown to excrete cyathostomin eggs earlier after treatment compared with older horses (R = 0.21, p = 0.015). Riding schools, stud farms and those declaring not to use separate summer and winter paddocks had significantly shorter ERPs (p <0.01).In conclusion, retained ERPs and no confirmed resistance to IVM were found in Swedish equine establishments practising selective anthelmintic treatment, and supports the use of selective deworming regimens as a means of reducing the risk of anthelmintic resistance development.

Investigation of bovine serum albumin‐specific IgE expression in horses

SummaryBackgroundNeonatal foals are born essentially agammaglobulinaemic and therefore must ingest colostrum or receive immunoglobulins to maintain health. Failure of passive transfer treatment involves administration of equine colostrum, plasma or commercial powdered colostrum (CPC). Anecdotal reports suggest the risk of anaphylaxis associated with plasma transfusion in neonates receiving CPC prior to gut closure. Bovine serum albumin (BSA) in CPC may serve as a target for BSA‐specific immunoglobulin E (IgE) in donor equine plasma.ObjectivesTo determine the presence of BSA‐specific IgE in samples of commercial equine plasma, samples were collected following routine vaccination in healthy horses and horses experiencing adverse vaccine reactions.Study designProspective observational.MethodsSerum was collected from: 65 healthy horses at days 0, 14, 28, 90, 180, 270 and 365 post‐vaccination; 26 horses after vaccine reaction at days 1, 180 or 270 post‐vaccination; 4 horses not vaccinated; and 9 horses from a commercial plasma donor herd. BSA‐specific IgE was determined using enzyme‐linked immunosorbent assay.ResultsBovine serum albumin‐specific IgE was not detected in non‐vaccinated horses and was identified in all vaccinated horses. Younger horses demonstrated a trend for higher fold changes in post‐vaccination BSA‐specific IgE expression compared to older horses. No significant difference in BSA‐specific IgE levels between commercial plasma donors and healthy horses was identified. No significant difference in post‐vaccination BSA‐specific IgE levels between the reactor and healthy horses at days 180 and 270 post‐vaccination were identified.Main limitationsSmall number of reactor horses at day 180 and 270 post‐vaccination with most samples being collected 24 h. There were no healthy horse samples for 24 h post‐vaccination; therefore, it was not possible to compare the groups at this timepoint.ConclusionsHorses may express BSA‐specific IgE following vaccination. There may be a risk of hypersensitivity type reaction when veterinarians administer commercial plasma to neonatal foals consuming CPC prior to gut closure.

Diagnosis and management of thyroid disorders and thyroid hormone supplementation in adult horses and foals.

Equine thyroid disorders pose a diagnostic challenge in clinical practice because of the effects of nonthyroidal factors on the hypothalamic-pituitary-thyroid axis, and the horse's ability to tolerate wide fluctuations in thyroid hormone concentrations and survive without a thyroid gland. While benign thyroid tumours are common in older horses, other disorders like primary hypothyroidism or hyperthyroidism in adult horses and congenital hypothyroidism in foals are rare. There is a common misunderstanding regarding hypothyroidism in adult horses, especially when associated with the clinical profile of obesity, lethargy, and poor performance observed in dogs and humans. Low blood thyroid hormone concentrations are often detected in horses as a secondary response to metabolic and disease states, including with the nonthyroidal illness syndrome; however, it is important to note that low thyroid hormone concentrations in these cases do not necessarily indicate hypothyroidism. Assessing equine thyroid function involves measuring thyroid hormone concentrations, including total and free fractions of thyroxine (T4) and triiodothyronine (T3); however, interpreting these results can be challenging due to the pulsatile secretion of thyroid hormones and the many factors that can affect their concentrations. Dynamic testing, such as the thyrotropin-releasing hormone stimulation test, can help assess the thyroid gland response to stimulation. Although true hypothyroidism is extremely rare, thyroid hormone supplementation is commonly used in equine practice to help manage obesity and poor performance. This review focuses on thyroid gland pathophysiology in adult horses and foals, interpretation of blood thyroid hormone concentrations, and evaluation of horses with thyroid disorders. It also discusses the use of T4 supplementation in equine practice.