Emerging outbreaks associated with equine coronavirus in adult horses

The purpose of this study was to describe clinical, hematological and fecal PCR results from 161 horses involved in outbreaks associated with ECoV. The outbreaks happened at four separate boarding facilities between November 2011 and April 2012 in the States of CA, TX, WI and MA. Following the molecular detection of ECoV in the feces from the initial index cases, the remaining herdmates were closely observed for the development of clinical signs. Fecal samples were collected from sick and healthy horses for the PCR detection of ECoV. All four outbreaks involved primarily adult horses. Fifty-nine horses developed clinical signs with 12–16 sick horses per outbreak. The main clinical signs reported were anorexia, lethargy and fever. Four horses from 3 different outbreaks were euthanized or died due to rapid progression of clinical signs. The cause of death could not be determined with necropsy evaluation in 2 horses, while septicemia secondary to gastrointestinal translocation was suspected in 2 horses. Blood work was available from 10 horses with clinical disease and common hematological abnormalities were leucopenia due to neutropenia and/or lymphopenia. Feces were available for ECoV testing by real-time PCR from 44 and 96 sick and healthy horses, respectively. 38/44 (86%) horses with abnormal clinical signs tested PCR positive for ECoV, while 89/96 (93%) healthy horses tested PCR negative for ECoV. The overall agreement between clinical status and PCR detection of ECoV was 91%. The study results suggest that ECoV is associated with self-limiting clinical and hematological abnormalities in adult horses.     

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.     

Longitudinal study of antimicrobial-resistant commensal Escherichia coli in the faeces of horses in an equine hospital

The increasing prevalence of antimicrobial resistance in bacteria represents a considerable problem for human and veterinary medicine, causing complications in the treatment of infections. Resistance in Escherichia coli from horses has been documented in commensal and pathogenic strains, but little information exists regarding the prevalence of such bacteria in hospitalised horses or associated risk factors. A longitudinal cohort study was conducted of 103 horses admitted to a referral equine hospital for more than 48 h, with faecal samples collected on hospital admission and subsequently every two days until discharge. Horses undergoing radioactive gamma scintigraphic examination, un-weaned foals and mares with un-weaned foals were excluded. Data were collected from enrolled animals, including antimicrobial treatment history and hospitalisation details. Samples were cultured for resistant E. coli; isolates had their antimicrobial resistance profile determined. High sample prevalence for resistant E. coli was identified for all antimicrobials examined except co-amoxiclav. The prevalence of resistance was consistently lower at admission, rising to a peak 4 days post-admission. Risk factors were analysed using multilevel, multivariable modelling, which identified significant clustering of resistance outcomes within horses. For all outcomes except trimethoprim resistance, the day the sample was obtained was significant, with increased risk of resistance for samples taken on day 2 or later. Antimicrobial treatment in the previous seven days and increased total daily dosages of cotrimoxazole prescribed in the hospital in the previous 24-48 h were associated with increased risk. Location within the hospital and admission reason were significant risk factors for some resistance outcomes. High levels of multidrug-resistant E. coli (47.7% of samples) and extended spectrum β-lactamase-producing E. coli (27.3% of samples) were recovered; such bacteria could significantly complicate treatment if they were the cause of infection and may represent a risk to personnel in close contact with hospitalised horses.     

Medical problems of adult horses, as ranked by equine practitioners

This paper reports the results of a survey conducted among members of the American Association of Equine Practitioners, concerning medical problems of adult horses. A one-page questionnaire listing 36 medical problems grouped by body system was completed by 1,149 veterinarians. The top-ranked disease was colic, followed by viral respiratory tract disease, endometritis, dermatitis, and parasitism. When responses were evaluated by type of practice, location of practice, and number of veterinarians in the practice, ranking of the top 2 diseases was the same for the total respondents. Ranking of diseases 3 through 5 varied when these criteria were taken into consideration.     

Lying behavior in horses in relation to box size

To analyze if horses' lying behavior is influenced by the size of their lying area, 8 horses were kept, first, in a large box—(2.5 × height of the horse)²m²—and then in a small box—(1.5 × height of the horse)²m²—or vice versa. After a 5-day adaptation period, the lying behavior (frequency and duration of sternal and lateral recumbency, rotating behavior just before lying down, and rolling behavior just before getting up) was observed from video recordings on 3 consecutive nights. The results showed that the duration of sternal recumbency was significantly longer in the large boxes than in the small boxes (P = .002). Furthermore, box size exerted an influence on the frequency of the rolling behavior shown before getting up, but box size was not the only factor affecting this behavior. We conclude that observations of the resting behavior of horses are necessary to make recommendations for the minimal size of stalls for horses.     

Molecular epidemiology of Salmonella Heidelberg in an equine hospital

From 1992 to 1997, multi-drug resistant (MDR) Salmonella Heidelberg isolates were cultured from a number of horses hospitalised in a veterinary hospital in Victoria, Australia. To examine the relationships between the cases, 28 isolates from the hospital were compared by pulsed field gel electrophoresis (PFGE), IS200 element profiles, antimicrobial resistance patterns, plasmid profiles and phage typing. The PFGE patterns following digestion with XbaI and BlnI restriction endonucleases showed that the isolates from the veterinary hospital originated from a common source. These isolates also had indistinguishable IS200 profiles. However, PFGE was more discriminatory than IS200 profiles. All the veterinary hospital isolates and one independent isolate had the same antimicrobial resistance pattern and had at least one plasmid in common. Localisation of antimicrobial resistance genes indicated that the veterinary hospital isolates had more than one plasmid carrying resistance genes and that the genes encoding sulphathiazole and trimethoprim resistance were not on these plasmids. Phage typing was ineffective as 22 of the 28 isolates were untypeable. In conclusion, the combination of different methods used for epidemiological studies suggested that a single strain of MDR S. Heidelberg was isolated from horses admitted to the hospital for 6 years and caused salmonellosis in susceptible horses within that period with no apparent correlation between the antimicrobials used and retention of its MDR phenotype.     

Assessment of a point-of-care lactate monitor in emergency admissions of adult horses to a referral hospital

BACKGROUND: Blood lactate concentration [LAC] is considered a useful indicator of disease severity in horses. Agreement of point-of-care (POC) lactate monitors with laboratory standards has not been established for clinically abnormal horses. Hypothesis: It was hypothesized that results from a POC lactate monitor would be in agreement with a laboratory-based measurement of [LAC]. ANIMALS: The study included adult horses presented for emergency evaluation. METHODS: A prospective observational study was performed. [LAC] was measured with whole blood (AWB) and plasma (APL) by means of a POC monitor (Accutrend) and compared with results from whole blood measured by a laboratory blood gas analyzer (NOVA). RESULTS: Samples from 221 horses were used to compare the 2 lactate measurement techniques. Agreement (p +/- SE) was closest between APL and NOVA (0.97 +/- 0.01); an average observed difference of 0.15 +/- 0.89 (mean +/- SD) and 95% limits of agreement (LOA) -1.89, 1.59 also were found. Agreement was preserved and 95% LOA further decreased in horses with NOVA [LAC] of <5 mM and PCV <40%. Agreement was modest when testing whole blood samples on the POC monitor with increased 95% LOA. CONCLUSIONS AND CLINICAL IMPORTANCE: Results indicate close agreement between NOVA and the POC monitor when [LAC] was measured with plasma. Results were less consistent at higher [LAC] but sufficiently reliable to follow trends. Although whole blood may be used with the POC monitor to identify clinically important hyperlactatemia, results may be insufficiently reliable to monitor trends.     

Prevalence of obesity in mature horses: an equine body condition study

Obesity is becoming a major health concern in horses because of its associations with insulin resistance, oxidative stress/inflammation, and laminitis. However, there is limited information on the prevalence of obesity in horses. The USDA National Animal Health Monitoring System (NAHMS) 1998 Equine study estimated that approximately 1.4% of the U.S. horse population is overweight or obese. The purpose of this study was to determine the prevalence of overweight and obesity in a subpopulation of horses in Virginia. A random sample of 300 mature, Light Breed horses (140 mares, 151 geldings, and 9 stallions) was selected from the VMRCVM Equine Field Service practice. Horses were evaluated during summer 2006. Body Condition Score (BCS) was assigned using a scale of 1 (emaciated) to 9 (obese) by two independent scorers. Neck circumference (cm) was measured at three locations and averaged (ANC). Girth, body length, and height at the withers were measured and used to calculate body weight (BW) and Body Mass Index (BMI). ANC and height at the withers were used to calculate Neck Circumference to Height Ratio (NCHR). Horses were categorized based on BCS as under condition (BCS <4), optimal condition (BCS 4–6), over condition (BCS 6.5–7), and obese condition (BCS 7.5–9). Six horses (2%) were under condition, 141 horses (47%) were in optimal condition, 96 horses (32%) were over condition, and 57 (19%) were obese. BW (p = 0.047), ANC, BMI and NCHR (all p < 0.001) increased with BCS. The prevalence of overweight and obesity in these horses was much higher than previously reported.     

Lying behavior and space requirements of German Schwarzbunt fattening calves in box stalls

In German Black Pied calves the height of wrist and length of body was measured and the want of space in lying situation in relation to height of wrist in different stadiums of age was calculated. For this relation was obtained the factor of 0.7, that means that 70 p.c. of the height of wrist are wanted by calves at the end of fattening (up to 250 kg) for lying. A totally extended behaviour in lying is kept during 1.6 and 0.9 p.c. of the length of day by calves which are offered an unlimited, limited space (boxes) respectively. More than 60 p.c. of the phase of this behaviour are lasting less than two minutes. Based on this behaviour found out and on the body measures this quotient seems to be justified as critical value for the minimum want of space in single boxes. As maximum width of a box 80 to 85 cm were calculated up to an age of 25 weeks. The length of the boxes should be related to the length of body and 45 cm more. This means for the found body measures a minimum length of about 180 cm. A higher value would correspond more to a species-related keeping of veal calves than a greater width of the box.     

Inheritance of equine sarcoid disease in Franches-Montagnes horses

The mode of inheritance for susceptibility to equine sarcoid disease (ES) remains unknown. The objectives of this study were to analyse a large sample of the Franches-Montagnes (FM) horse population and investigate the heritability and mode of inheritance for susceptibility to ES. Horses were clinically examined for the presence of sarcoid tumours. A standardized examination protocol and client questionnaire were used and a pedigree- and subsequent segregation-analysis for the ES trait performed. To investigate the mode of inheritance, five models were evaluated and compared in a hierarchical way.The analyses reveal that variation in susceptibility to ES is best explained by a model incorporating polygenic variation. The possible effect of a major gene, such as specific equine leukocyte antigen alleles, is unlikely, but cannot be ruled-out entirely. The heritability of the phenotype on the observation scale for the trait ‘affected with ES’ was estimated to be 8%. A corrected value for the heritability on a liability scale was estimated at 21% and it is therefore possible to estimate breeding values for ES. The arguments against the practical implementation of an estimated breeding value in a multifactorial condition like ES are discussed.     

Differentiation of strains of equine arteritis virus of differing virulence to horses by growth in equine endothelial cells

OBJECTIVE: To compare growth characteristics of strains of equine arteritis virus (EAV) of differing virulence to horses in rabbit kidney (RK)-13 cells and equine endothelial cells (EECs) cultured from the pulmonary artery of a foal. SAMPLE POPULATION: 13 strains of EAV, including 11 field isolates of differing virulence to horses; the highly virulent, horse-adapted Bucyrus strain; and the modified-live virus (MLV) vaccine derived from it. PROCEDURE: The growth characteristics of the 13 strains were compared in EECs and RK-13 cells. Viral nucleoprotein expression, cytopathogenicity, and plaque size were compared to determine whether growth characteristics of the 13 strains were predictive of their virulence to horses. RESULTS: Cytopathogenicity, viral nucleoprotein expression, and plaque size induced by all 13 viruses were similar in RK-13 cells, whereas virulent strains of EAV caused significantly larger plaques in EECs than did the avirulent strains of EAV. Paradoxically, the highly attenuated MLV vaccine and 1 field isolate of EAV caused plaques in EECs that were larger than those caused by any of the other viruses, and sequence analysis confirmed the field isolate of EAV to be indistinguishable from the MLV vaccine. CONCLUSIONS AND CLINICAL RELEVANCE: With the notable exception of the MLV vaccine, growth of the various strains of EAV in EECs was predictive of their individual virulence to horses. Thus, EECs provide a relevant and useful model to further characterize determinants of virulence and attenuation amongst strains of EAV.