Molecular epidemiology of Streptococcus zooepidemicus infection in naturally occurring equine respiratory disease

The objective of the study was to characterise the molecular epidemiology of Streptococcus zooepidemicus infection among isolates collected sequentially from recently weaned, pasture maintained Welsh mountain ponies with naturally occurring respiratory disease. Weekly nasopharyngeal and tracheal lavage samplings over a 10-week period were conducted in 29 ponies. Two PCR typing methods based on characterisation of the M-protein hypervariable (HV) region and the 16S-23S rRNA gene intergenic spacer were then applied to isolates of S. zooepidemicus recovered from nasopharyngeal swab and tracheal wash samples. S. zooepidemicus infection was highly prevalent during the study, being isolated from 94% of tracheal washes and 88% of nasopharyngeal swabs. Among 39 different S. zooepidemicus types isolated, more were isolated from the trachea (n=33) than the nasopharynx (n=27). There was evidence from temporal patterns of infection for clonal succession over time by the more prevalent S. zooepidemicus types. Novel S. zooepidemicus types were identified, including previously untyped HV regions and intra-strain multiples of both the HV region and intergenic spacer types.     

Cryptosporidiosis in Horses of Urban Areas of Porto Alegre,Rio Grande do Sul,Southern Brazil

The aim of the present study was to detect the presence of Cryptosporidium spp. oocysts in the feces of horses used in military training and in horseback riding activities. A total of 90 fecal samples were collected from three sites in the city of Porto Alegre, state of Rio Grande do Sul, Brazil as follows: 71 samples were obtained from the Brazilian Army, seven from the hospital accredited with the School of Veterinary Medicine of Universidade Federal do Rio Grande do Sul, and 12 from a facility offering animal rest and training. All samples were collected between the months of January and February, 2008. They were screened microscopically for oocysts using the modified Ziehl–Neelsen staining technique. Oocysts were classified on the basis of their microscopic characteristics. The overall infection rate of horses as determined by microscopic analysis was 27.87% (25/90) and was identified only in horses raised in the Brazilian Army, with a rate of 35.21% (25/71). The morphometric analysis of oocysts revealed a mean size of 4.78 × 4.0 μm and a shape index of 1.16. None of the infected horses appeared to be clinically ill.     

Seroprevalence of Sarcocystis neurona and Its Association With Neurologic Disorders in Argentinean Horses

Equine protozoal myeloencephalitis (EPM) is generally caused by Sarcocystis neurona and can produce substantial economic losses on equine production in America. The aims of the present study were to evaluate the seroprevalence of S. neurona in the main horse-production area of Argentina and associate it with the occurrence of neurologic disorders. Serum samples were collected from 640 horses in nine Argentinean provinces. Most of the samples correspond to animals ≥1.5-year-old from different breeds (n = 628); 12 samples were from younger horses. Further seroprevalence comparison was conducted from the older animals grouped with (n = 148) or without neurologic signs (n = 480). Immunoblot: proteins from 2 × 10⁷S. neurona merozoites were used as antigen on each membrane. Reactivity to antigens with relative mobility of 7, 10, and 16 kDa was considered specific for antibodies against S. neurona; reactivity at 30 kDa was recorded separately. The overall seroprevalence for S. neurona was 26.1% (167/640), and all the provinces had positive horses. Seroprevalence of animals with neurologic signs was greater (P < .001) than what was observed in normal horses (39.2% vs. 22.1%), with an odds ratio of 2.27. Reactivity at 30 kDa was detected in 71% of all samples. This study identified a wide distribution of S. neurona–positive animals in Argentina and horses with neurologic signs having a greater seroprevalence than normal horses. Sarcocystis neurona infection should be considered for early differential diagnosis and treatment of animals with neurologic disorders to decrease the economic impact of EPM in Argentina.     

Immunization with Trichophyton verrucosum Vaccine in Hunter/Jumper and Dressage Horses with Naturally Occurring Trichophyton equinum Infection: A Prospective,Randomized, Double-Blinded,Placebo-Controlled Clinical Trial

The aim of the current study was to investigate the efficacy of Trichophyton verrucosum vaccine in hunter/jumper and dressage horses with trichophytosis caused by Trichophyton equinum (cross immunity). A total of 25 hunter/jumper and dressage horses between the ages of 2 and 14 years, naturally infected with Trichophyton equinum, were enrolled and randomly assigned to either a placebo or an intramuscular lyophilized Trichophyton verrucosum vaccine group. Clinical evaluations were done by the same investigator, who scored clinical healing at the beginning, during, and at the end of the treatment and was blinded to allocation to the groups. At the end of the trial, vaccine treatment significantly decreased the investigator's clinical scores (P < .001), and no significant changes were detected in the placebo treatment group. In all of the horses vaccinated, the lesions improved gradually within 7 to 12 days after vaccination. Complete clinical remission was detected within 28 to 42 days, and all treated horses became culture negative within 25 days of starting treatment. No clinical healing was observed in nine untreated control horses throughout the study. No recurrence was observed in treated horses within 10 months after therapy. Results of the current study indicate that inactivated Trichophyton verrucosum vaccine may be a safe and effective therapy for horses with Trichophyton equinum infection.     

An outbreak of fatal hemorrhagic pneumonia caused by Streptococcus equi subsp. zooepidemicus in shelter dogs

An outbreak of fatal hemorrhagic pneumonia with 70~90% morbidity and 50% mortality occurred in an animal shelter in Yangju, Gyeonggi Province, Korea. Clinically, the affected dogs showed severe respiratory distress within 48 h after arriving in the shelter. The dead were found mainly with nasal bleeding and hematemesis. At necropsy, hemothorax and hemorrhagic pneumonia along with severe pulmonary consolidation was observed, though histopathological analysis showed mainly hemorrhagic bronchopneumonia. Lymphoid depletion was inconsistently seen in the spleen, tonsil and bronchial lymph node. Gram-positive colonies were shown in blood vessels or parenchyma of cerebrum, lung, liver, spleen, and kidney. Also, Streptococcus (S.) equi subsp. zooepidemicus was isolated from the various organs in which the bacterium was microscopically and histologically detected. In addition, approximately 0.9 Kb specific amplicon, antiphagocytic factor H binding protein, was amplified in the bacterial isolates. In this study, we reported an outbreak of canine hemorrhagic bronchopneumonia caused by S. equi subsp. zooepidemicus in an animal shelter in Yangju, Korea.     

Demographic and Environmental Risk Factors for Exposure to Lawsonia intracellularis in Horses in Israel

Equine proliferative enteropathy (EPE) is an enteric disease of foals that is caused by Lawsonia intracellularis. Clinical cases have been reported worldwide; however, data regarding the epidemiology of L. intracellularis in horses are scarce. Thus far, L. intracellularis has not been reported in the Middle East. The objectives of this study were to determine whether the causative agent of EPE exists in horses in Israel and in the Palestinian Authority and to define environmental and demographic risk factors for exposure. Fecal and serum samples were collected from horses from various regions of the country. The presence of L. intracellularis in horses in Israel was determined by real-time polymerase chain reaction (PCR), and seroprevalence was determined by enzyme-linked immunosorbent assay. One fecal sample of 136 tested (0.7%), was PCR positive. Sixty-seven sera samples (30.5%) of 220 horses in sentinel farms had anti-L. intracellularis antibodies. Low seroprevalence was found in foals both from Israel and from the Palestinian Authority (4.2% and 13.3%, respectively). In logistic regression models, geographical locations, management type, and age were found to be significant risk factors associated with seroprevlaence to L. intracellularis. No significant correlation was found between environmental variables and L. intracellularis seroprevalence after controlling for management type. These results support the existence of L. intracellularis in horses in both Israel and the Palestinian Authority. The reasons for the relatively low prevalence are currently not known and may be the result of different management, low exposure to free-living animals, and differences in environmental variables affecting the bacterial burden.     

Etiologic and epidemiologic analysis of bacterial infectious upper respiratory disease in Thoroughbred horses at the Seoul Race Park

Infectious upper respiratory disease (IURD) of Thoroughbred racehorses has been a frequent problem (29.6% of incidence) at the Seoul Race Park (Korea). Risk factors for IURD include the season with a high transfer rate (summer and fall), the stabling period (≤ 3 months), and age (2 to 3 years old), suggesting that the movement and new environment may have depressed the immune system of the horses and decreased their ability to respond properly to pathogens. The bacterial strains (n = 98) isolated from IURD horses included Pseudomonas spp., Escherichia coli, Staphylococcus spp., Streptococcus equi subsp. equi and zooepidemicus.     

A Preliminary Study Examining the Digital Cushion in Horses

The digital cushion is important for the dissipation of impact as the foot contacts the ground. If there is inefficient energy dissipation, potential exists for changes to occur in the foot. Although ultrasonic imaging of the digital cushion has been reported, it is unknown if these measurements account for compositional changes that have been reported across age, breed, and between fore and hind feet. Therefore, the objective of this preliminary study was to establish baseline values in mature, stock type horses with adequate body condition score (BCS). To meet this objective, 24 mature, stock-type horses of similar age, height, and weight were used to establish baseline values for the digital cushion thickness in the live horse. All horses were sound at the time of data collection and had no known history of long-term lameness conditions. Digital cushion thickness of the left fore and left hind foot was determined using ultrasound through the transcuneal approach. Data were analyzed using the PROC MEANS and PROC GLM procedure of SAS with a least square means statement. Significance was set at P ≤ .05. Mean values (±standard error [SE]) for age, weight, height, and BCS were 10.7 ± 0.86 years, 476.2 ± 7.75 kg, 153.56 ± 0.90 cm, and 5.6 ± 0.12, respectively. Mean values (±SE) for the digital cushion of the left fore and left hind were 0.96 ± 0.03 and 1.02 ± 0.04 cm, respectively. When comparing the left fore and left hind, there was no significant difference observed. Overall, baseline values of digital cushion thickness for fore and hind feet were established, allowing for future studies to assess the different variables known to affect digital cushion composition.     

A Multiplex Polymerase Chain Reaction Assay for Direct Detection and Differentiation of β-Hemolytic Streptococci in Clinical Samples from Horses

Streptococcus equi subspecies equi, S equi subspecies zooepidemicus, and S dysgalactiae subspecies equisimilis are β-hemolytic Streptococci, often isolated from horses with respiratory or genital diseases. The aim of this study was (i) defining and validating a multiplex polymerase chain reaction (PCR) protocol for identifying these Streptococci in bacterial cultures and for detecting them directly in equine clinical specimens, and (ii) defining and validating a cheap DNA extraction protocol for clinical specimens. When respiratory and genital samples from symptomatic and asymptomatic horses were tested by bacterial culture and by multiplex PCR, all the 150 samples culture-positive for S equi, S zooepidemicus, or S equisimilis were also positive by PCR. Of 150 culture-negative samples, 143 were negative by PCR. Seven samples were positive by PCR but negative by bacteriology. The multiplex PCR protocol described in this study is proven suitable for a sensitive, specific, and rapid detection and identification of S equi, S zooepidemicus, and S equisimilis in cultured bacterial colonies, as well as in clinical specimens from symptomatic or asymptomatic horses. The inclusion of internal control primers in the PCR protocol excludes false-negative results. A cheap DNA extraction method has been also validated for swabs, tracheal aspirates, bronchoalveolar lavage, and guttural pouches lavage samples.     

Effect of Yeast Culture Supplementation on Digestibility of Varying Forage Quality in Mature Horses

Supplementation of yeast culture to equine diets has improved digestion of nutrients in some studies but not others. Improving the digestibility of lower-quality forages could be advantageous both for the producer and for the horse's health. The objective of this study was to evaluate the effect of yeast culture on digestibility of high- and low-quality forage in mature horses. Sixteen geldings (483.6 ± 25.5 kg and 6.8 ± 3.2 years), of Quarter Horse (n = 14) and Thoroughbred (n = 2) breeding, were used in a 4 × 4 Latin square design with 28-day treatment periods. Russell Bermuda grass hay of either high (13.1% crude protein (CP), 73.1% neutral detergent fiber (NDF), 35.3% acid detergent fiber (ADF), and 6.0% ash) or low (8.1% CP, 75.3% NDF, 37.6% ADF, and 4.3% ash) quality was offered at 1.35% of body weight (BW, dry matter [DM] basis). Diets consisted of high-quality forage with the addition of yeast culture (HY), high-quality forage without yeast culture (HC), low-quality forage with the addition of yeast culture (LY), and low-quality forage without yeast culture (LC). All horses were fed a commercial grain mix (12.6% CP, 25.4% NDF, 12.1% ADF, and 4.0% ash) offered at 0.45% of BW (DM basis) daily. Yeast culture was added to the grain mix during the morning feeding at a rate of 56 g per horse. Body weight was measured weekly and feed intake was adjusted accordingly. Fecal samples were obtained every 6 hours on the last 3 days of each treatment period. Horses receiving low-quality hay (LY and LC) had greater (P < .01) intake expressed as a percentage of BW compared with horses receiving high-quality hay (HY and HC). No influence of yeast culture supplementation was seen on intake of grain or forage (P < .23 and P < .62, respectively). Digestibility of DM, organic matter (OM), CP, and NDF were greater (P < .01, P < .01, P < .01, and P < .01, respectively) for the diets with high-quality forage compared with the diets with low-quality forage. Dry matter, CP, and NDF digestibilities were greater (P < .09, P < .03, and P < .05, respectively) for horses receiving LY compared with LC. Supplementation of yeast culture to mature horses improved digestibility of lower-quality Bermuda grass hay.     

Seroprevalence of Leishmania sp. Infection in Healthy Horses Housed in Endemic Areas in Tuscany

This study carried out an epidemiological survey of seroprevalence of positive immunofluorescence antibody test (IFAT) results for Leishmania infantum in horses living in Tuscany, where the disease in the dog is endemic and no cases of equine leishmaniasis were observed. Inclusion criteria were (1) horses housed for more than 2 years in endemic areas; (2) horses grazing 24 hours a day outside; and (3) horses living on farms where affected dogs were housed. Two blood samples each were collected from 277 horses from June to October 2011 (T1) and from December 2011 to February 2012 (T2), and IFAT was performed for L. infantum. A dermatologic examination was performed to detect the presence of skin lesions. No animals had skin abnormalities. At T1, 18 of 277 horses had positive results for IFAT, while at the second sampling (T2) 277 of 277 samples were negative. In conclusion, our seroprevalence is lower than that in Spain but higher than that in Greece. Our results suggest the presence of a transient humoral response to L. infantum in horses.     

甲氧苄啶对蒲公英体外抗菌增效作用的研究

采用微量棋盘稀释法测定了蒲公英、甲氧苄啶及两药联用对金黄色葡萄球菌、大肠杆菌和沙门氏菌的最小抑菌浓度(MIC),计算蒲公英与甲氧苄啶联用的组分抑菌浓度(FIC)指数。结果表明,蒲公英与甲氧苄啶联用对金黄色葡萄球菌、大肠杆菌和沙门氏菌的FIC指数分别为0.75、0.75和1,呈相加作用。采用平板计数的方法,测定了蒲公英与甲氧苄啶联用作用于3种细菌1、2、4和8 h后的细菌数,并计算杀菌率。利用最小二乘法对杀菌率进行拟合,计算出甲氧苄啶增强蒲公英体外抗金黄色葡萄球菌、大肠杆菌和沙门氏菌作用的最优添加剂量分别为4.0、1.8和2.0 mg/g。     

PCR based differentiation between Streptococcus dysgalactiae subsp. equisimilis strains isolated from humans and horses

Streptococcus dysgalactiae subsp. equisimilis (SDSE) can be severely pathogenic in humans and is increasingly isolated from horses with respiratory, reproductive or other diseases, although it is often considered a commensal bacterium. Here a PCR protocol is described for identifying SDSE recovered from humans. A multiplex PCR targeting the 16S rRNA and the streptokinase precursor gene has been optimized for differentiating between SDSE strains isolated from humans and those isolated from horses. Previously, the sequence of the streptokinase precursor gene of SDSE recovered from horses has been found in two human cases of pneumonia in Japan.     

Retrospective Study on Seroprevalence of Borrelia burgdorferi Antibodies in Horses in Minnesota

To determine the seroprevalence of Borrelia burgdorferi antibodies in horses in Minnesota, the database of the Veterinary Diagnostic Laboratory, University of Minnesota, was searched over a 10-year period (May 2001 to May 2010). A total of 1,260 equine serum samples submitted by 112 veterinary clinics were tested using an indirect fluorescent antibody test. Samples with titers of ≥1:320 were considered positive. The average rate of seroprevalence was 58.7%, indicating high exposure of horses to B burgdorferi in Minnesota. Our results indicate that borreliosis should be considered as a differential in cases of horses with undiagnosed musculoskeletal or neurologic disease.     

Bacteriological and Molecular Detection of Streptococcus equi subsp. equi and Streptococcus equi subsp. zooepidemicus in Equines of Northern India

Present study was undertaken to study the prevalence of β-haemolytic streptococci in equine of northern temperate region of Jammu and Kashmir, India. One hundred and forty one samples were collected in duplicate from nasopharyngeal tract of diseased (53) and apparently healthy equine (88) for isolation and direct PCR. A total of 77 isolates of streptococci were recovered from 141 samples with an overall prevalence rate of 54.60%. Out of these 77 isolates, 52 were from diseased and 25 from apparently healthy animals. Of the 77 isolates, 4 were identified as Streptococcus equi subsp. equi, 56 as S. equi subsp. zooepidemicus and 17 as S. dysgalactiae subsp. equisimilis. Thus the overall prevalence of S. equi subsp. equi, S. equi subsp. zooepidemicus and S. dysgalactiae subsp. equisimilis was 2.83, 39.71 and 12.05% respectively. The sensitivity of the PCR for the detection of S. equi species was found higher when attempted from direct swab samples.     

A Nonlinear Model for Estimating Hoof Surface Area in Unshod Meat-type Horses

The aim of this study was to develop a simple, inexpensive, and noninvasive technique for estimating the hoof surface area (HSA) of unshod horses under field conditions. It was hypothesized that HSA in horses can be extrapolated from simple linear hoof measurements. Two linear measurements—lateromedial width and dorsoplantar width—were obtained from all four feet of 57 unshod meat-type horses. Different algorithms for determining HSA were developed. The most simple equation was HSA = (1.229 × LM)^1.071 × (DP)^0.772 (where LM = lateromedial width and DP = dorsoplantar width), representing a good nonlinear model with a standard deviation of error for the estimate of 5.150 and a coefficient of multiple determination of 0.9384. This formula may be helpful as a repeatable, nonintrusive, and easily performed in vivo estimation of the hoof surface of unshod horses, at least in the studied breed.