Bugs and drugs: a systems biology approach to characterising the effect of moxidectin on the horse's faecal microbiome.

BACKGROUND: Anthelmintic treatment is a risk factor for intestinal disease in the horse, known as colic. However the mechanisms involved in the onset of disease post anthelmintic treatment are unknown. The interaction between anthelmintic drugs and the gut microbiota may be associated with this observed increase in risk of colic. Little is known about the interaction between gut microbiota and anthelmintics and how treatment may alter microbiome function. The objectives of this study were: To characterise (1) faecal microbiota, (2) feed fermentation kinetics in vitro and (3) metabolic profiles following moxidectin administration to horses with very low (0 epg) adult strongyle burdens. HYPOTHESIS: Moxidectin will not alter (1) faecal microbiota, (2) feed fermentation in vitro, or, (3) host metabolome. RESULTS: Moxidectin increased the relative abundance of Deferribacter spp. and Spirochaetes spp. observed after 160 h in moxidectin treated horses. Reduced in vitro fibre fermentation was observed 16 h following moxidectin administration in vivo (P = 0.001), along with lower pH in the in vitro fermentations from the moxidectin treated group. Metabolic profiles from urine samples did not differ between the treatment groups. However metabolic profiles from in vitro fermentations differed between moxidectin and control groups 16 h after treatment (R2 = 0.69, Q2Y = 0.48), and within the moxidectin group between 16 h and 160 h post moxidectin treatment (R2 = 0.79, Q2Y = 0.77). Metabolic profiles from in vitro fermentations and fermentation kinetics both indicated altered carbohydrate metabolism following in vivo treatment with moxidectin. CONCLUSIONS: These data suggest that in horses with low parasite burdens moxidectin had a small but measurable effect on both the community structure and the function of the gut microbiome.

Shortened egg reappearance after ivermectin or moxidectin use in horses in the UK.

This study reports ivermectin and moxidectin egg reappearance periods (ERP) from UK horses with persistently positive faecal egg counts (FEC), defined as positive FEC within the ERP of an anthelmintic post-treatment, or with FECs that remained positive after the normal ERP post-anthelmintic treatment. A selected population of UK pleasure horses deemed at high risk of strongyle infection was studied. The earliest ERP recorded after ivermectin or moxidectin, using first positive FEC, was 5 weeks. From 16 premises where moxidectin was used, five had ERP ≥12 weeks using two further metrics. For premises where moxidectin was administered to only one animal (present or tested), and evaluated as one group (n = 61), ERP was ≥10 weeks. For premises where ivermectin was used, the ERP was ≥5 weeks. Premises with only one horse (present or tested), dosed with ivermectin (n = 31), analysed as one group, demonstrated egg reappearance ≥6 weeks. These field data suggest shortened ERPs following macrocyclic lactone treatment compared to previously published values (8-10 and >13 weeks respectively) when these drugs were first marketed.

Ovicidal efficacy of fenbendazole after treatment of horses naturally infected with cyathostomins.

The ovicidal activity of benzimidazole (BZ) anthelmintics is unique and not seen in other drug classes. Such ovicidal efficacy is not widely reported for equine cyathostomins, nor has this activity been tested in the face of BZ resistance. Although the product label states that fenbendazole is for use against BZ-susceptible cyathostomins, susceptibility testing is rarely performed. In this field-based study, the ovicidal efficacy of fenbendazole in horses (n=39) harbouring BZ-resistant cyathostomins was compared when dosed at 7.5mg/kg body weight (BW) orally, as a single dose per os (n=21) or daily for five consecutive days in feed (n=18). Suppression of egg hatch rate was observed in the single and five- day treatment groups; a significant difference between pre- and post-treatment egg hatch rates (P<0.05) was observed for three days after treatment with a single dose of fenbendazole (on premises with BZ-resistant cyathostomins), and for three days after treatment for five consecutive days with fenbendazole (on premises with BZ-resistant cyathostomins). Post treatment numbers of eggs and larvae remained significantly lower (P<0.05) than pre-treatment levels to the end of the trial. We conclude that in the face of BZ-resistant cyathostomins the ovicidal effect of fenbendazole persist for three days after both a single oral dose of 7.5mg/kg per os and after treatment orally for five consecutive daily doses at 7.5mg/kg in feed.

Prevention of post operative complications following surgical treatment of equine colic: Current evidence.

Changes in management of the surgical colic patient over the last 30 years have resulted in considerable improvement in post operative survival rates. However, post operative complications remain common and these impact negatively on horse welfare, probability of survival, return to previous use and the costs of treatment. Multiple studies have investigated risk factors for post operative complications following surgical management of colic and interventions that might be effective in reducing the likelihood of these occurring. The findings from these studies are frequently contradictory and the evidence for many interventions is lacking or inconclusive. This review discusses the current available evidence and identifies areas where further studies are necessary and factors that should be taken into consideration in study design.

Characterisation of the faecal metabolome and microbiome of Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: The intestinal bacterial community of the horse is a key determinant of intestinal and whole body health. Understanding the bacterial community structure and function is an important foundation for studies of intestinal health and disease. OBJECTIVES: To describe the faecal bacterial community and volatile organic compounds (VOCs) of the faecal metabolome of healthy Thoroughbred racehorses and to characterise responses to dietary supplementation with amylase-rich malt extract. STUDY DESIGN: Intervention study. METHODS: Faecal samples were collected noninvasively before and 6 weeks after supplementation in 8 privately owned Thoroughbred racehorses in active race training. Faecal metabolome was characterised using thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS), with spectral analysis performed using AMDIS and compared against the NIST database. Taxonomic description of the faecal microbiota was achieved using error-corrected 454 pyrosequencing data from 16S rRNA gene amplicons. RESULTS: The faecal metabolome of our study population was dominated by organic acids, alcohols and ketones. We identified 81 different VOCs only 28 of which were present in >50% of samples indicating functional diversity. Faecal VOC profiles differed between first and second sampling point, some VOCs being significantly reduced post supplementation, consistent with a marked response to dietary amylase-rich malt extract. Faecal microbiota was characterised as highly diverse; samples demonstrated verifiable diversity in the range 1200-3000 operational taxonomic units (OTUs) per individual. The methods used also describe high levels of infrequent, low abundance OTUs. Faecal microbial community structure was found to be different following dietary supplementation. Differences in several low abundance bacterial taxa were detected and also some evidence of interhorse variation in response. CONCLUSIONS: The volatile faecal metabolome of Thoroughbred racehorses is dominated by organic acids, alcohols and ketones; this study demonstrates that dietary supplementation with amylase-rich malt extract may significantly alter the profile of VOCs. The faecal microbiome is highly diverse, dominated by Firmicutes and Bacteroidetes. Small but significant changes in microbial community structure were detected following dietary supplementation. This study describes the faecal metabolome and microbiome of healthy Thoroughbred racehorses against which future studies of disease and dietary intervention can be benchmarked.

Management and horse-level risk factors for recurrent colic in the UK general equine practice population.

REASONS FOR PERFORMING STUDY: Recurrent colic occurs frequently in the general horse population but little evidence exists about what factors place horses at greater risk of recurrent colic. OBJECTIVES: To quantify time-varying and non time-varying risk factors for recurrent colic among horses attended by first-opinion veterinary surgeons in northwest England. STUDY DESIGN: Nested case-control study. METHODS: A nested case-control study was conducted on data from a prospective longitudinal cohort study of 127 horses recruited subsequent to an episode of medical colic. Data were collected on management and recurrent colic episodes at 4-monthly intervals by telephone questionnaires. All recurrent colic episodes were selected as cases; controls were unmatched and randomly selected from all horse-time at risk. Data relating to the 30 days prior to the date of colic or control selection were used to determine exposure status. Multivariable logistic regression analyses were used to determine risk factors for recurrent colic. RESULTS: In total, 59 cases and 177 controls were included. The final model showed that horses that displayed crib-biting/windsucking (odds ratio [OR] 10.1, 95% confidence interval [CI] 2.5-41.0) or weaving behaviour (OR 3.9, 95% CI 1.5-10.1) had an increased risk of recurrence of colic. Increasing time at pasture reduced the risk of recurrence (OR 0.99, 95% CI 0.99-1.0). A significant interaction was found suggesting that the risk associated with crib-biting/windsucking may be modified by feeding fruit/vegetables; however, further research is required before recommendations for feeding practices can be made. CONCLUSIONS: This study suggests that sufficient access to pasture may be an important means of reducing recurrent colic risk. The behavioural risk factors highlight individuals who may be at increased risk of recurrent colic and whose colic prevention strategies should be carefully managed.

Dominant components of the Thoroughbred metabolome characterised by (1) H-nuclear magnetic resonance spectroscopy: A metabolite atlas of common biofluids.

REASONS FOR PERFORMING STUDY: Metabonomics is emerging as a powerful tool for disease screening and investigating mammalian metabolism. This study aims to create a metabolic framework by producing a preliminary reference guide for the normal equine metabolic milieu. OBJECTIVES: To metabolically profile plasma, urine and faecal water from healthy racehorses using high resolution (1) H-nuclear magnetic resonance (NMR) spectroscopy and to provide a list of dominant metabolites present in each biofluid for the benefit of future research in this area. STUDY DESIGN: This study was performed using 7 Thoroughbreds in race training at a single time point. Urine and faecal samples were collected noninvasively and plasma was obtained from samples taken for routine clinical chemistry purposes. METHODS: Biofluids were analysed using (1) H-NMR spectroscopy. Metabolite assignment was achieved via a range of one- and 2-dimensional experiments. RESULTS: A total of 102 metabolites were assigned across the 3 biological matrices. A core metabonome of 14 metabolites was ubiquitous across all biofluids. All biological matrices provided a unique window on different aspects of systematic metabolism. Urine was the most populated metabolite matrix with 65 identified metabolites, 39 of which were unique to this biological compartment. A number of these were related to gut microbial host cometabolism. Faecal samples were the most metabolically variable between animals; acetate was responsible for the majority (28%) of this variation. Short-chain fatty acids were the predominant features identified within this biofluid by (1) H-NMR spectroscopy. CONCLUSIONS: Metabonomics provides a platform for investigating complex and dynamic interactions between the host and its consortium of gut microbes and has the potential to uncover markers for health and disease in a variety of biofluids. Inherent variation in faecal extracts along with the relative abundance of microbial-mammalian metabolites in urine and invasive nature of plasma sampling, infers that urine is the most appropriate biofluid for the purposes of metabonomic analysis.

Expression of PGP 9.5 by enteric neurons in horses and donkeys with and without intestinal disease.

Intestinal motility disorders are an important problem in horses and donkeys and this study was carried out in order to evaluate the enteric neurons in animals with and without intestinal disease. Surplus intestinal tissue samples were collected from 28 horses undergoing exploratory laparotomy for colic. In addition, surplus intestinal samples from 17 control horses were collected immediately following humane destruction for clinical conditions not relating to the intestinal tract. Similar samples were also collected during routine post-mortem examinations from 12 aged donkeys; six animals were humanely destroyed for conditions related to the intestinal tract, while the remaining six were humanely destroyed for other reasons including dental and orthopaedic diseases. Tissue samples were fixed in formalin and immunohistochemical labelling was performed targeting the enteric neurons using a polyclonal antibody specific for the neuronal marker PGP 9.5. The distribution and density of neuronal networks were assessed qualitatively and semiquantitatively. There was strong PGP 9.5 expression in both the horse and donkey samples and labelling was detected throughout the tissue sections. In both species, PGP 9.5-immunoreactive nerve fibres were detected in all layers of the intestinal tract, both in large and small intestinal samples. Networks of enteric neurons were present in the donkey with a similar distribution to that seen in the horse. There was no demonstrable difference in enteric neuronal density and distribution in the groups of animals with intestinal disease compared with those without, apart from two (out of 28) horses with intestinal disease that showed a marked reduction in PGP 9.5 immunoreactivity. Apart from these two animals, this total cohort analysis differs from some previously observed findings in horses with intestinal disease and may therefore reflect the different pathophysiological processes occurring in varying intestinal conditions resulting in colic both in the donkey and the horse.

Risk factors for large colon volvulus in the UK.

REASONS FOR PERFORMING STUDY: Risk factors for large colon volvulus (LCV) in the horse have not been previously reported. Knowledge of these risk factors may allow the introduction of measures that could be taken to minimise the incidence of LCV. OBJECTIVES: To investigate risk factors for LCV in the horse. METHODS: A prospective, multicentre, unmatched case-control study was conducted over a 24 month period in the UK. Data on 69 cases and 204 control horses, from 4 veterinary hospitals, were obtained via telephone questionnaires. Multivariable logistic regression was used to identify associations between horse and management-level variables and the likelihood of LCV. RESULTS: Increasing height, multiple colic episodes in the previous 12 months and mares, with a greater odds ratio in mares that had previously foaled, were associated with increased risk of LCV. Receiving medication (excluding anthelmintic treatment) in the previous 7 days and quidding behaviour were also associated with increased risk. Management-level variables associated with greater risk of LCV were an increase in the hours of stabling in the previous 14 days, an increasing number of horses on the premises, and 3 or more people involved in the horse's care. Variables related to nutrition associated with increased risk of LCV were being fed hay, being fed sugar-beet, a change in pasture in the previous 28 days, and an alteration in the amount of forage fed in the last 7 days. CONCLUSIONS: This study has identified factors that may assist in the recognition of horses with increased risk of LCV and factors that might be altered to minimise the incidence of LCV. POTENTIAL RELEVANCE: Clinicians can use this information to identify horses at risk of LCV and to provide evidence-based advice to owners of these horses.

Survival of horses following strangulating large colon volvulus.

REASONS FOR PERFORMING STUDY: The pattern of long-term survival and specific factors associated with long-term survival have not previously been evaluated in horses with a strangulating large colon volvulus (LCV). OBJECTIVES: To provide data on the long-term survival of horses with LCV and to identify pre-, intra- and post operative variables associated with survival. METHODS: Clinical data and long-term follow-up information were obtained from 116 horses with a strangulating LCV (≥360°) undergoing general anaesthesia. Two multivariable Cox proportional hazards models for post operative survival time were developed: Model 1 included all horses and evaluated preoperative variables and Model 2 included horses that survived anaesthesia and evaluated pre-, intra- and post operative variables. RESULTS: The study population comprised 116 horses. Eighty-nine (76.7%) survived general anaesthesia. Of these, the percentage that survived until discharge, to one year and to 2 years was 70.7%, 48.3% and 33.7%, respectively. Median survival time for horses that survived general anaesthesia was 365 days. In Model 1 increased preoperative packed cell volume (PCV) was significantly associated with reduced post operative survival (hazard ratio [HR] 1.08, 95% confidence interval [CI] 1.05-1.11). However, this effect changed over time. In Model 2 abnormal serosal colour intraoperatively (HR 3.61, 95% CI 1.55-8.44), increased heart rate at 48 h post surgery (HR 1.04, 95% CI 1.02-1.06), and colic during post operative hospitalisation (HR 2.63, 95% CI 1.00-6.95), were all significantly associated with reduced post operative survival. CONCLUSIONS: Survival time in horses with a LCV was associated with preoperative PCV, serosal colour, heart rate at 48 h post operatively and colic during post operative hospitalisation. POTENTIAL RELEVANCE: This study provides evidence-based information on the long-term survival of horses with LCV and identifies parameters that may assist decision-making by clinicians and owners.

Surgical lesions of the small colon and post operative survival in a UK hospital population.

REASONS FOR PERFORMING STUDY: There is limited information about risk factors and survival associated with disorders of the small colon requiring surgical management. OBJECTIVES: 1) To document the types of surgical lesion in horses where pathology of the small (descending) colon was the primary cause of abdominal pain, 2) to describe the short- and long-term survival of these cases and identify factors associated with survival and 3) to identify preoperative variables associated with localisation of a lesion to the small colon. METHODS: Clinical data and long-term follow-up were obtained for horses that underwent exploratory laparotomy over a 10-year period. Descriptive data were generated for short- and long-term survival and survival analysis performed to identify factors associated with reduced survival. Univariable and multivariable relationships were explored using a Cox proportional hazards model. Preoperative factors associated with increased likelihood of a small colon lesion were explored, using controls randomly selected from horses undergoing exploratory laparotomy for treatment of colic unrelated to the small colon. RESULTS: The study population included 84 horses. Of horses with small colon lesions recovered from anaesthesia, the percentage that survived until discharge, one year and 2 years following surgery, was 91.0, 81.0 and 73.5%, respectively. Median survival time for horses in which a resection had been performed was 1029 vs. 3072 days in the nonresection group. Small colon cases were more likely to have shown a longer duration of colic signs prior to admission (P<0.001) and to develop post operative diarrhoea (P = 0.001) when compared with surgical controls. CONCLUSIONS: Lesions of the small colon carry a good prognosis for survival following surgery. Resection and anastomosis was the only factor associated with reduced long-term survival. POTENTIAL RELEVANCE: This study provides information about lesion types and post operative survival that may be used to assist informed decision-making when managing these cases.

Field efficacy of praziquantel oral paste against naturally acquired equine cestodes in Ethiopia.

The efficacy of an oral formulation of praziquantel (Equitape, Horse paste, Fort Dodge) in the reduction of cestode egg counts and serum antibody level against Anoplocephala perfoliata was assessed in 44 donkeys under field conditions. The donkeys were confirmed both by faecal examination and serum antibody assessed by an enzyme-linked immunosorbent assay to have natural infection with tapeworms. The donkeys were randomly allocated into treatment (n = 22) and control (n = 22) groups. The treatment group was treated with both praziquantel and ivermectin (Ivomec, Merial) at a dose rate of 1 mg/kg and 200 µg/kg, respectively while the control group was treated only with ivermectin. Faecal samples were collected before treatment (day-0) and 2, 6, 8, 12, and 16 weeks post-treatment while blood samples were collected before treatment and 8 and 16 weeks after treatment and analysed. The results of the study demonstrated that praziquantel paste was highly effective in reducing cestode eggs in donkeys and had an efficacy of more than 99 % until week 16 (day 112). No cestode egg reappearance by 16 weeks post-treatment in any animal in the treatment group was observed while donkeys in the control group continued shedding cestode eggs. The immunological assay also showed a significant reduction in serum antibody level against A. perfoliata in treated donkeys compared to the control group (p = 0.0001). This marked decrease in serum antibody level indicates reduced risk of cestode-associated colic and other gastrointestinal disorders and clinical diseases. No adverse reactions or clinical effects were encountered in any animal within either group throughout the trial period.

Equine cestodosis: a sero-epidemiological study of Anoplocephala perfoliata infection in Ethiopia.

A 12/13 kDa antigen, tapeworm ELISA test, developed for use in horses, was used to detect parasite-specific serum antibody, IgG(T), in the serum of donkeys. In a pilot study the 12/13 kDa antigen was tested and proved to detect the antibody, IgG(T), in donkey sera. Blood samples from 797 donkeys, naturally exposed to cestode infection, from four geographical localities were collected and sera were prepared and analysed. There was substantial serological evidence that donkeys were potentially infected with A. perfoliata. A range of ELISA OD values were obtained from the serological assay. Over 26% and 7.5% of the donkeys were moderately and highly infected, respectively, showing at least a 34% sero-prevalence. The rest, 66.1%, were either with low infection intensity or negative for A. perfoliata infection. The risk of infections, both in sero-prevalence and intensity, as determined by ELISA optical density (OD), were highest in the highland areas of Ethiopia where pastures are low-lying and wet, and permanent pasture management is regularly practised. Sex, age and body condition of the donkeys had no significant effect either on prevalence of the infection or on the serum antibody level. These results indicate a risk of intestinal disorders, particularly, colic, associated with A. perfoliata infection in donkeys.

Adipose tissue-derived adiponectin expression is significantly associated with increased post operative mortality in horses undergoing emergency abdominal surgery.

REASONS FOR PERFORMING STUDY: Adipose tissue is an important source of inflammatory cytokines (adipokines) and adiposity has been identified as having a significant effect on human morbidity and mortality. Obesity is also an emerging welfare problem in the UK horse population, but the role that it plays in secondary diseases is unclear. OBJECTIVES: To examine the expression of inflammation-related adipokine genes in retroperitoneal adipose tissue of horses undergoing emergency abdominal surgery and to explore associations with adiposity and post operative survival. METHODS: Retroperitoneal adipose tissue samples were obtained from 76 horses undergoing emergency abdominal surgery. Real-time PCR was used to measure gene expression for leptin, adiponectin, tumour necrosis factor-alpha, macrophage chemoattractant protein-1, macrophage inhibitory factor, serum amyloid A, haptoglobin and interleukin-1. Multivariate patterns of adipokine expression were explored with principal component analysis (PCA), whilst univariable associations with post operative survival were tested in a Cox proportional hazards model. RESULTS: Leptin gene expression was higher in overweight and obese horses than in lean animals. Expression of mRNA encoding adiponectin mRNA in visceral adipose tissue was positively associated with increased post operative mortality (hazard ratio 1.31, 95% CI 1.05-1.65). However, PCA did not demonstrate multivariable patterns of adipokine gene expression from visceral adipose tissue associated with body mass index or with survival. CONCLUSIONS: In horses presented with acute intestinal disease, increased adiponectin gene expression from retroperitoneal adipose tissue is associated with an increased risk of mortality. Obesity assessed by BMI had no association with increased post operative mortality in horses with primary gastrointestinal disease. POTENTIAL RELEVANCE: Further study is warranted on the expression and effects of adipokines, particularly adiponectin, and correlation with postoperative outcome.

Factors associated with survival of epiploic foramen entrapment colic: a multicentre, international study.

REASONS FOR PERFORMING STUDY: Epiploic foramen entrapment (EFE) has been associated with reduced post operative survival compared to other types of colic but specific factors associated with reduced long-term survival of these cases have not been evaluated in a large number of horses using survival analysis. OBJECTIVE: To describe post operative survival of EFE cases and to identify factors associated with long-term survival. METHODS: A prospective, multicentre, international study was conducted using clinical data and long-term follow-up information for 126 horses diagnosed with EFE during exploratory laparotomy at 15 clinics in the UK, Ireland and USA. Descriptive data were generated and survival analysis performed to identify factors associated with reduced post operative survival. RESULTS: For the EFE cohort that recovered following anaesthesia, survival to hospital discharge was 78.5%. Survival to 1 and 2 years post operatively was 50.6 and 34.3%, respectively. The median survival time of EFE cases undergoing surgery was 397 days. Increased packed cell volume (PCV) and increased length of small intestine (SI) resected were significantly associated with increased likelihood of mortality when multivariable analysis of pre- and intraoperative variables were analysed. When all pre-, intra- and post operative variables were analysed separately, only horses that developed post operative ileus (POI) were shown to be at increased likelihood of mortality. CONCLUSIONS: Increased PCV, increased length of SI resected and POI are all associated with increased likelihood of mortality of EFE cases. This emphasises the importance of early diagnosis and treatment and the need for improved strategies in the management of POI in order to reduce post operative mortality in these cases. POTENTIAL RELEVANCE: The present study provides evidence-based information to clinicians and owners of horses undergoing surgery for EFE about long-term survival. These results are applicable to university and large private clinics over a wide geographical area.

Recurrent colic in the horse: incidence and risk factors for recurrence in the general practice population.

REASONS FOR PERFORMING STUDY: The frequency of recurrent colic in the UK equine general practice population is previously unreported. Elucidating risk factors for recurrent colic could provide a basis for clinical decision making and interventions. OBJECTIVES: To determine the incidence rate of and risk factors for recurrent colic. HYPOTHESES: Horse management, prophylactic health care and innate behaviour contribute to the risk of recurrent colic. METHODS: A cohort of 127 horses was enrolled at the point of a veterinary-diagnosed medical colic episode. Participating owners completed a baseline and 3 follow-up telephone questionnaires over one year. Clinical details of each colic episode were collected with data on management, behaviour and preventive healthcare. Incidence was calculated using time at risk data; non-time varying covariates were assessed for association with recurrent colic using multivariable logistic regression. RESULTS: The recurrence rate was 50 colic events/100 horse years at risk (HYAR). Including only veterinary attended recurrent colic episodes the incidence was 35 colic events per 100 HYAR. A multivariable logistic regression model was built to explore non-time varying risk factors for recurrence collected from baseline data. The model showed that horses that have a known dental problem (OR 5.5, 95% CI 1.3, 23.1) or crib-bite/windsuck (OR 12.1, 95% CI 1.4, 108.1) were at increased risk of recurrence during the year following a colic event. CONCLUSIONS AND POTENTIAL RELEVANCE: The incidence of recurrence in horses following a medical episode of colic is high in this population and represents a welfare concern. The incidence rate can be used to compare intervention efficacy in similar populations. Identified risk factors could provide the basis for management interventions or highlight at risk individuals.

A nationwide surveillance scheme for equine grass sickness in Great Britain: results for the period 2000-2009.

REASONS FOR PERFORMING STUDY: Equine grass sickness (EGS) remains a frequently fatal disease of equids in Great Britain (GB). The first nationwide surveillance scheme for EGS was developed to obtain information on the occurrence of EGS and to help facilitate future proposed intervention studies, such as vaccine trials. OBJECTIVES: To collect both retrospective and prospective data on cases of EGS occurring in GB since 2000 and to assess potential risk factors for categories of EGS and survival after chronic EGS. METHODS: Prospective data were collected using a nationwide surveillance scheme for EGS that was developed and initiated in 2007. Data were collected by means of postal and online questionnaires documenting both retrospective premises-level and prospective case-level information. Data on outcomes of EGS category and survival after chronic grass sickness (CGS) were analysed using univariable logistic regression. RESULTS: Descriptive data for 1410 EGS cases occurring in GB in the decade between the beginning of 2000 and the end of 2009 are presented. Univariable logistic regression analyses identified that CGS cases in Scotland were significantly more likely to survive than those occurring elsewhere in GB. There was no relationship between case details and the category of EGS or the outcome among CGS cases. CONCLUSIONS: EGS affected equids throughout England, Scotland and Wales. Although an overall average of 141 cases were reported to the nationwide surveillance scheme annually, this number of cases was not consistent between years. Around 50% of CGS cases survived, although regional differences in survival rates existed, probably due to variation in expertise of care and/or disease severity. POTENTIAL RELEVANCE: This study provides information on the spatiotemporal occurrence of EGS in GB during the last decade. Data from the nationwide surveillance scheme can be used in developing protocols for future intervention studies such as Clostridium botulinum vaccine trials.

Plasma endotoxin in horses presented to an equine referral hospital: correlation to selected clinical parameters and outcomes.

REASONS FOR PERFORMING STUDY: Endotoxaemia is frequently presumed on the basis of clinical signs in horses with colic. OBJECTIVE: Measurements of plasma endotoxin (LPS) are rarely made in clinical cases and there is little information on the correlations between this variable, clinical variables and outcomes. OBJECTIVES: To measure LPS levels in plasma of horses presented to the Philip Leverhulme Equine Hospital on admission and daily for up to 4 days and to relate LPS levels to selected clinical parameters, such as heart rate and packed cell volume, and outcomes. METHODS: Blood samples were collected and stored at -20°C prior to assay of the plasma using a validated kinetic chromogenic Limulus amoebocyte lysate (LAL) assay. Clinical parameters and outcome variables were collected from hospital records. Associations were determined by Chi-squared test and logistic regression analysis. RESULTS: Daily blood samples were collected from 234 horses. LPS was detected in 26.5% of the study population and in 29% of those horses presented for colic. Horses providing samples with detectable LPS were more likely to die whilst in the hospital than those that did not (P = 0.045). Horses presenting with colic were more likely to have detectable LPS in their plasma than noncolic cases (P = 0.037), although LPS was detected in the plasma of 8 out of 42 noncolic horses. A horse that did not meet the study definition of clinical endotoxaemia was 10 times less likely to provide a positive LPS sample (OR 0.10, 95% CI: 0.05-0.22). CONCLUSIONS: The proportion of horses providing samples with detectable LPS was similar to other studies. POTENTIAL RELEVANCE: LPS was detected in the minority of horses presented with colic. Increased levels of LPS positively correlated with packed cell volume and with risk of mortality in colic cases.