Seroprevalence of SARS-CoV-2 in 1186 Equids Presented to a Veterinary Medical Teaching Hospital in California from 2020 to 2022

While some companion animals have been shown to be susceptible to SARS-CoV-2, their role in the COVID-19 pandemic has remained poorly investigated. Equids are susceptible to SARS-CoV-2 based on the similarity of the human ACE-2 receptor and reports of infection. Clinical disease and prevalence factors associated with SARS-CoV-2 infection in equids have not yet been investigated. The aim of this study was to determine the seroprevalence of SARS-CoV-2 and selected prevalence factors in 1186 equids presented for various conditions to a Veterinary Medical Teaching Hospital over a two-year period. Blood samples were tested for SARS-CoV-2 antibodies using an ELISA targeting the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. Further, selected prevalence factors (season, age, breed, sex, presenting complaint) were retrieved from the medical records. No information was available on whether the horses had come into contact with COVID-19-positive individuals. Among the study animals, 42/1186 (3.5%) horses had detectable SARS-CoV-2 antibodies. Amongst the prevalence factors investigated, only seasonality (spring) was associated with a greater frequency of seropositivity to SARS-CoV-2. Horses with medical and surgical complaints were more likely to test seropositive to SARS-CoV-2 compared to horses presented for routine health care procedures, suggesting more frequent and/or longer interactions with individuals with COVID-19. While horses can become infected with SARS-CoV-2 via the occasional spillover from COVID-19 individuals, clinical disease expression remains subclinical, making horses an unlikely contributor to the spread of SARS-CoV-2.

Frequency of detection of respiratory pathogens in nasal secretions from healthy sport horses attending a spring show in California

The objective of this study was to determine detection frequency of respiratory viruses (equine influenza virus (EIV), equine herpesvirus-1 (EHV-1), EHV-2, EHV-4, EHV-5, equine rhinitis A virus (ERAV), ERBV) and bacteria (Streptococcus equi ss. equi (S. equi), S. equi ss. zooepidemicus (S. zooepidemicus)) in 162 nasal secretions and 149 stall swabs from healthy sport horses attending a spring show in California. Nasal and stall swabs were collected at a single time point and analyzed using qPCR. The detection frequency of respiratory pathogens in nasal secretions was 38.9% for EHV-2, 36.4% for EHV-5, 19.7% for S. zooepidemicus, 1.2% for ERBV, 0.6% for S. equi and 0% for EIV, EHV-1, EHV-4 and ERAV. The detection frequency of respiratory pathogens in stall swabs was 65.8% for S. zooepidemicus, 33.5% for EHV-2, 27.5% for EHV-5, 3.3% for EHV-1, 1.3% for EHV-4 and 0% for EIV, ERAV, ERBV and S. equi. Commensal viruses and bacteria were frequently detected in nasal secretions and stall swabs from healthy sport horses. This was in sharp contrast to the subclinical shedding of well-characterized respiratory pathogens. Of interest was the clustering of five EHV-1 qPCR-positive stalls from apparently healthy horses with no evidence of clinical spread. The results highlight the role of subclinical shedders in introducing respiratory pathogens to shows and their role in environmental contamination. The results also highlight the need to improve cleanliness and disinfection of stalls utilized by performance horses during show events.

Investigation of the Use of Non-Invasive Samples for the Molecular Detection of EHV-1 in Horses with and without Clinical Infection

The purpose of this study was to explore sampling options for a reliable and logistically more feasible protocol during a large EHV-1 outbreak. Seventeen horses with clinical infection as well as nineteen healthy herdmates, all part of an EHM outbreak, were enrolled in the study. Each horse was sampled two–four times at intervals of 2–6 days during the outbreak. All samples were collected using 6′′ rayon-tipped swabs. Nasal secretions were used as the diagnostic sample of choice. Additional samples, including swabs from the muzzle/nares, swabs from the front limbs, rectal swabs, swabs of the feed bin, and swabs of the water troughs were collected as well. All swabs were tested for the presence of EHV-1 by qPCR. With the exception of two EHV-1 qPCR-positive swabs from two different horses, all remaining swabs collected from healthy herdmates tested qPCR-negative for EHV-1. For horses with clinical infection, EHV-1 was detected in 31 nasal swabs, 30 muzzle/nares swabs, 7 front limb swabs, 7 feeders, 6 water troughs and 6 rectal swabs. Not all positive muzzle/nares swabs correlated with a positive nasal swab from the same set, however, and all other positive swabs did correlate with a positive nasal swab in their respective set. The agreement between nasal swabs and muzzle/nares swabs was 74%. The sampling of non-invasive swabs from the muzzle/nares should facilitate the identification of EHV-1 shedders during an outbreak, allowing for prompt isolation and implementation of biosecurity measures.

Investigation of cross-regional spread and evolution of equine influenza H3N8 at US and global scales using Bayesian phylogeography based on balanced subsampling

Equine influenza virus (EIV) is a highly contagious pathogen of equids, and a well-known burden in global equine health. EIV H3N8 variants seasonally emerged and resulted in EIV outbreaks in the United States (US) and worldwide. The present study evaluated the pattern of cross-regional EIV H3N8 spread and evolutionary characteristics at US and global scales using Bayesian phylogeography with balanced subsampling based on regional horse population size. A total of 297 Haemagglutinin (HA) sequences of global EIV H3N8 were collected from 1963 to 2019 and subsampled to global subset (n = 67), raw US sequences (n = 100) and US subset (n = 44) datasets. Discrete trait phylogeography analysis was used to estimate the transmission history of EIV using four global and US genome datasets. The North American lineage was the major source of globally dominant EIV variants and spread to other global regions. The US EIV strains generally spread from the southern and midwestern regions to other regions. The EIV H3N8 accumulated approximately three nucleotide substitutions per year in the HA gene under heterogenous local positive selection. Our findings will guide better decision making of target intervention strategies of EIV H3N8 infection and provide the better scheme of genomic surveillance in the US and global equine health. This article is protected by copyright. All rights reserved.

Investigation of the Role of Healthy and Sick Equids in the COVID-19 Pandemic through Serological and Molecular Testing

Simple Summary

The objective of the present study was to determine if horses are susceptible to SARS-CoV-2. Nasal swabs from 667 equids with acute onset of fever and respiratory signs were tested by qPCR for SARS-CoV-2. Further, 633 serum samples collected from a cohort of 587 healthy racing Thoroughbreds with possible exposure to humans with SARS-CoV-2 infection were tested for antibodies to SARS-CoV-2 using an ELISA targeting the receptor-binding domain of the spike protein. All 667 horses with fever and respiratory signs tested qPCR-negative for SARS-CoV-2. A total of 35/587 (5.9%) Thoroughbred racing horses had detectable IgG antibodies to SARS-CoV-2. While horses appear to be susceptible to SARS-CoV-2 when in close contact with humans with SARS-CoV-2 infection, clinical disease was not observed in the study horses. Experimental challenge studies using pure inocula are needed in order to study the clinical, hematological, molecular, and serological features of adult horses infected with SARS-CoV-2.

Abstract

More and more studies are reporting on the natural transmission of SARS-CoV-2 between humans with COVID-19 and their companion animals (dogs and cats). While horses are apparently susceptible to SARS-CoV-2 infection based on the homology between the human and the equine ACE-2 receptor, no clinical or subclinical infection has yet been reported in the equine species. To investigate the possible clinical role of SARS-CoV-2 in equids, nasal secretions from 667 horses with acute onset of fever and respiratory signs were tested for the presence of SARS-CoV-2 by qPCR. The samples were collected from January to December of 2020 and submitted to a commercial molecular diagnostic laboratory for the detection of common respiratory pathogens (equine influenza virus, equine herpesvirus-1/-4, equine rhinitis A and B virus, Streptococcus equi subspecies equi). An additional 633 serum samples were tested for antibodies to SARS-CoV-2 using an ELISA targeting the receptor-binding domain of the spike protein. The serum samples were collected from a cohort of 587 healthy racing Thoroughbreds in California after track personnel tested qPCR-positive for SARS-CoV-2. While 241/667 (36%) equids with fever and respiratory signs tested qPCR-positive for at least one of the common respiratory pathogens, not a single horse tested qPCR-positive for SARS-CoV-2. Amongst the racing Thoroughbreds, 35/587 (5.9%) horses had detectable antibodies to SARS-CoV-2. Similar to dogs and cats, horses do not seem to develop clinical SARS-CoV-2 infection. However, horses can act as incidental hosts and experience silent infection following spillover from humans with COVID-19. SARS-CoV-2-infected humans should avoid close contact with equids during the time of their illness.

Diarrhea outbreak associated with coronavirus infection in adult dairy goats

Background

Infection by coronaviruses cause gastrointestinal disease in many species. Little is known about its prevalence and importance in goats.

Objective

Identify the etiology, demographics, and clinical features of an outbreak of diarrhea in adult goats.

Hypothesis

Bovine coronavirus (BCoV) PCR would detect viral material in feces of goats in the herds involved in the diarrhea outbreak.

Animals

Twelve herds with 4 to 230 adult goats were affected. Goats sampled for fecal PCR were ≥1‐year‐old: 25 from affected herds and 6 from a control herd.

Methods

This is a cross‐sectional descriptive study of an outbreak of diarrheal disease in adult goats. BCoV PCR primers for the spike (S) or nucleocapsid (N) proteins were used to test fecal material from affected goats. The N protein sequencing and phylogenetic analysis was performed. Herd records and owner surveys were used to characterize morbidity, clinical signs, and treatment.

Results

In 2 affected herds 18/25 of animals had at least 1 positive BCoV PCR test. Goats from affected herds were significantly more likely to be PCR positive than the control herd (OR 8.75, 95% CI 1.11‐104, P = .05). The most common clinical signs were change in fecal consistency (19/20) and decreased milk production (14/15). Phylogenetic analysis of the N protein showed this virus was closely related to a bovine‐like coronavirus isolated from a giraffe.

Conclusions and Clinical Importance

Bovine coronavirus primers detected nucleic acids of the N and S proteins in feces of goats in affected herds. Coronavirus shedding frequency was temporally associated with the outbreak.

Horses affected by EPM have increased sCD14 compared to healthy horses

Equine protozoal myeloencephalitis (EPM) is a debilitating neurologic disease affecting horses across the Americas. Gaps in understanding the inflammatory immune response in EPM-affected horses create difficulties with diagnosis and treatment, subsequently negatively impacting the prognosis of affected horses. The purpose of the current study was to evaluate circulating levels of the inflammatory immune marker soluble CD14 (sCD14), in horses with EPM (n = 7) and determine if they differed from healthy neurologically normal horses (n = 6). Paired sera and cerebrospinal fluid (CSF) samples were analyzed for sCD14. Inclusion criteria for EPM horses consisted of the presence of neurologic signs consistent with EPM, Sarcocystis neurona surface antigens 2, 4/3 (SnSAG 2, 4/3) ELISA serum: CSF antibody ratio ≤ 100, and a postmortem diagnosis of EPM. Control horses were neurologically normal, healthy horses with SnSAG 2, 4/3 ELISA serum: CSF antibody ratios of > 100. Serum anti-Sarcocystis neurona antibodies indicate that healthy control horses were exposed to S. neurona but resistant to developing clinical EPM. EPM cases had significantly greater concentrations of sCD14 in CSF samples compared to control horses and increased serum sCD14 concentrations. A positive correlation between sCD14 serum and CSF concentrations was observed in EPM-affected horses but not healthy horses. Soluble CD14 is an inflammatory marker, and the study results suggest it is elevated in EPM patients. When performed in conjunction with clinical evaluation and standard antibody testing, there may be potential for sCD14 to be utilized as a correlate for EPM.

Fecal PCR testing for detection of Clostridium perfringens and Clostridioides difficile toxin genes and other pathogens in foals with diarrhea: 28 cases

Clostridium perfringens and Clostridioides difficile cause significant morbidity and mortality in foals. Antemortem diagnosis of C. perfringens infection has been complicated by a paucity of tests available for toxin detection. Fecal PCR panels have assays for a variety of C. perfringens toxin gene sequences as well as for several other foal gastrointestinal pathogens. We evaluated results of a comprehensive fecal diarrhea PCR panel in 28 foals that had been presented to a referral hospital because of diarrhea. Sixteen (57%) foals were positive for C. perfringens and/or C. difficile toxin gene sequences on fecal PCR, including 3 foals positive for NetF toxin. These foals were younger (p = 0.0029) and had higher hematocrits (p = 0.0087), hemoglobin (p = 0.0067), and red blood cell concentrations (p = 0.028) than foals with diarrhea that tested negative for clostridial toxins. The foals had lower total protein concentrations (p = 0.045) and were more likely to have band neutrophils on a CBC (p = 0.013; OR: 16.2). All 3 foals with NetF toxin gene sequences detected in feces survived to discharge, indicating that diarrhea caused by NetF toxigenic C. perfringens isolates is not uniformly fatal.

Challenges in navigating molecular diagnostics for common equine respiratory viruses

Equine respiratory viruses remain a leading cause of equine morbidity and mortality, with the resurgence of certain infections, an increasing population of elderly, more susceptible horses, the growth of international equine commerce, and an expansion in geographic distribution of pathogens. The focus of rapid diagnosis of infectious diseases has also shifted recently, with the appearance and increasing importance of nucleic acid amplification-based techniques, primarily polymerase chain reaction (PCR), at the expense of traditional methods such as clinical microbiology. While PCR is fast, reliable, cost-effective, and more sensitive than conventional detection methods, careful interpretation of diagnostic test results is required, taking into account the clinical status of the patient, sample type, assay used and biological relevance of the detected viruses. The interpretation of common equine respiratory viruses such as influenza virus (EIV), alpha herpesviruses (EHV-1, EHV-4), arteritis virus (EAV) and rhinoviruses (ERAV, ERBV) is straight forward as causality can generally be established. However, the testing of less-characterized viruses, such as the gamma herpesviruses (EHV-2, EHV-5), may be confusing, considering their well-established host relationship and frequent detection in both diseased and healthy horses. For selected viruses, absolute quantitation (EHV-1 and EHV-4) and genotyping (EIV and EHV-1) has allowed additional information to be gained regarding viral state and virulence, respectively. This information is relevant when managing outbreaks so that adequate biosecurity measures can be instituted and medical interventions can be considered. The goal of this review is to help the equine practitioner navigate through the rapidly expanding field of molecular diagnostics for respiratory viruses and facilitate the interpretation of results.

Investigation of the Bi-Weekly Administration of Diclazuril on the Antibody Kinetics to Sarcocystis Neurona in Healthy Horses

The aim of this study was to determine if bi-weekly administration of diclazuril at half the label dose would reduce seroprevalence and magnitude of titers to S. neurona in healthy horses naturally exposed to the apicomplexan protozoal parasite. 12 healthy adult horses were moved from a low-risk exposure to a farm with high exposure rate to S. neurona in their horse population. The horses were randomly assigned to either a treatment or a control group. Treatment consisted in the administration of half the label dose (0.5 mg/kg) of diclazuril (Protazil) pelleted top dress twice weekly (every 3-4 days) for 12 months. Prior to initiation of treatment and monthly thereafter, blood was collected for the detection of antibodies to S. neurona using a quantitative immunoassay. Further, trough plasma diclazuril levels were determined every 60 days. All 20 horses remained healthy during the entire study period. Seroprevalence to S. neurona decreased initially in the treatment group to 50% at 30 days post-treatment commencement. This was followed by a slow increase in seroprevalence in the treatment group before reaching 100% in both groups by 90 days post-treatment commencement. The seroprevalence remained 100% in both groups from 90 to 360 study days. While titer distribution between the two groups was similar at study commencement, treated horses had significantly lower titers throughout the treatment period (P < 0.05). All treated study horses had detectable plasma trough diclazuril levels at the 6 time points and the levels were above the concentration known to inhibit S. neurona in vitro (1.0 ng/mL). The administration of diclazuril pelleted top dress at half the label dose twice weekly was able to maintain low titers to S. neurona in healthy adult horses naturally exposed to the protozoal parasite. Further, trough diclazuril levels were in excess of the minimal concentration known to inhibit S. neurona.

Genome-informed characterisation of antigenic drift in the haemagglutinin gene of equine influenza strains circulating in the United States from 2012 to 2017

Equine influenza virus (EIV) is a major infectious pathogen causing significant respiratory signs in equids worldwide. Voluntary surveillances in the United States recently reported EIV detection in horses with respiratory signs even with adequate vaccine protocols and biosecurity programs and posed a concern about suboptimal effectiveness of EIV vaccine in the United States. This study aims to determine the genetic characteristics of 58 field EIV H3N8 strains in the United States from 2012 to 2017 using the phylogenetic analysis based on the haemagglutinin (HA) gene. Amino acid substitution and acquisition of N-glycosylation of the HA gene were also evaluated. Phylogenetic analysis identified that almost all US field strains belonged to the Florida clade 1 (FC1) except one Florida clade 2 strain from a horse imported in 2014. US EIV strains in 2017 shared 11 fixed amino acid substitutions in the HA gene, compared to the vaccine strain (A/equine/Ohio/2003), and two additional amino acid substitutions were detected in 2019. The introduction of foreign EIV strains into the United States was not detected, but antigenic drift without acquisition of N-glycosylation in the HA gene was observed in US field strains until 2017. Considering the global dominance of FC1 strains, subsequent antigenic drift of US EIV strains should be monitored for better effectiveness of the EIV vaccine in the United States and global equine industries.

Investigation of an EHV-1 Outbreak in the United States Caused by a New H752 Genotype

Here we report on an EHV-1 outbreak investigation caused by a novel genotype H752 (histidine in amino acid position 752 of the ORF 30 gene). The outbreak involved 31 performance horses. Horses were monitored over a period of 35 days for clinical signs, therapeutic outcome and qPCR results of EHV-1 in blood and nasal secretions. The morbidity of the EHV-1 outbreak was 84% with 26 clinically infected horses displaying fever and less frequently anorexia and distal limb edema. Four horses showed mild transient neurological deficits. Clinically diseased horses experienced high viral load of EHV-1 in blood and/or nasal secretions via qPCR, while subclinically infected horses had detectable EHV-1 mainly in nasal secretions. The majority of infected horses showed a rise in antibody titers to EHV-1 during the outbreak. All 31 horses were treated with valacyclovir, while clinically infected horses further received flunixin meglumine and sodium heparin. This investigation highlights various relevant aspects of an EHV-1 outbreak caused by a new H752 genotype: (i) importance of early detection of EHV-1 infection; (ii) diagnostic challenge to assess H752 genotype; (iii) apparent benefit of valacyclovir use in the early stage of the outbreak; and (iv) weekly testing of blood and nasal secretions by qPCR in order to monitor individual infection status and lift quarantine.

Equine respiratory viruses, airway inflammation and performance in thoroughbred racehorses

Equine asthma is a common cause of poor performance in racehorses but it is unclear if respiratory viruses contribute to its etiology. The objective of the study was to determine if respiratory viruses were associated with clinical signs and bronchoalveolar lavage fluid (BALF) cytology in Thoroughbred racehorses. Equine herpesviruses (EHV-1, 2, 4, 5) and equine rhinitis A and B viruses (ERBV, ERAV) genomes were quantified by qPCR in nasopharyngeal, tracheal, and BALF samples collected after racing. The relationships between virus detection and load and clinical signs, performance, BALF cytology, and environmental exposures were examined with generalized linear mixed models. Ninety-two samples were collected from 31 horses. EHV-1 and ERAV were not found; EHV-4 was detected in only one sample. EHV-2, EHV-5 and ERBV were more likely to be detected in upper airway samples than in BALF (P < 0.0001). Neither respiratory virus detection nor load was associated with clinical signs or performance. Nasopharyngeal detection and load of ERBV and tracheal detection and load of EHV-5 were associated with increased proportions of neutrophils in BALF (P < 0.003). However, nasopharyngeal detection and load of EHV-5 was not (P = 0.11). Nasopharyngeal detection and load of EHV-2 were associated with decreased BALF mast cell proportions. Respirable dust exposures were significantly higher in horses with detection of ERBV when compared to horses with no detectable ERBV (P < 0.001). Our results suggest that ERBV, EHV-2 and EHV-5 are commonly present in upper airways of healthy racehorses; however, the role they play in the etiology of equine asthma remains unclear.

What have we learned from 7 years of equine rhinitis B virus qPCR testing in nasal secretions from horses with respiratory signs

BACKGROUND

Equine rhinitis B virus (ERBV) has been given little attention by practitioners compared to other respiratory viruses, mainly because of the lack of diagnostic modalities and association with clinical disease. The objective of the study was to determine the frequency of detection of ERBV in nasal secretions from 6568 horses with acute onset of respiratory signs.

METHODS

ERBV-positive qPCR results from nasal secretions submitted to a molecular diagnostic laboratory from 2013 to 2019 were reviewed.

RESULTS

A total of 333 ERBV qPCR-positive samples (5.1%) were detected with increasing yearly frequency since the introduction of the assay in 2013. In comparison, only three of 356 (0.8%) healthy horses tested qPCR-positive for ERBV. Median age for ERBV qPCR-positive horses was 3 years of age, and fever, coughing and nasal discharge were the most common signs reported. Further, co-infections with other respiratory pathogens were reported in 73 (21.9%) of ERBV qPCR-positive samples.

CONCLUSION

ERBV is a commonly detected respiratory virus from nasal secretions of young horses presenting with fever, nasal discharge and coughing.

Hemagglutinin inhibition antibody responses to commercial equine influenza vaccines in vaccinated horses

The use of a hemagglutination inhibition (HI) assay to assess humoral immune response to equine influenza virus (EIV) vaccines from various manufacturers administered to previously immunized adult horses was investigated. Subjects were allocated into one of 3 groups and vaccinated with various commercially available vaccines. Groups were subdivided into subjects that received 1 dose of a particular vaccine and those that received a second dose, 30 d later. Serum was collected at various times to assess antibody responses to contemporary EIV Florida sub-lineage strains. Statistical significance was set at P < 0.05 and all groups had a significant increase in antibody titers pre- and post-administration of the first dose. In contrast, there was no significant difference between day 30 titers and titers at subsequent time points, regardless of protocol. We concluded that administration of various commercial influenza vaccines containing a different sub-lineage clade stimulated equivalent HI antibody titers after 1 booster vaccination.

Molecular detection of Sarcocystis neurona in cerebrospinal fluid from 210 horses with suspected neurologic disease

An ante-mortem diagnosis of equine protozoal myeloencephalitis (EPM) is presently based on clinical presentation, immunodiagnostics performed on serum and cerebrospinal fluid (CSF), and ruling out other neurological disorders. Molecular techniques introduce a novel and promising approach for the detection of protozoal agents in CSF. Hypothesizing that real-time PCR (rtPCR) can be a useful complement to EPM diagnostics, 210 CSF samples from horses suspected of neurological disease with EPM included as a differential diagnosis were tested using rtPCR to detect Sarcocystis neurona DNA and immunodiagnostics targeting antibodies against the same pathogen, performed on serum and CSF samples. Molecular and immunological results were compared with respect to origin of the horse, time of the year, signalment, clinical signs and treatment history. Twenty-five horses tested positive in CSF for S. neurona by rtPCR only, while 30 horses had intrathecally-derived antibodies to S. neurona only (serum to CSF ratio ≤ 64 by indirect fluorescent antibody test - IFAT), and 13 horses tested rtPCR-positive in CSF with evidence of intrathecally-derived antibodies to S. neurona. Previous treatment for EPM was the only variable presenting statistical difference between the two testing modalities, highlighting that animals with history of anti-protozoal treatment were more likely to test positive solely in IFAT, while horses without treatment were more likely to test positive by rtPCR only. The results support the use of molecular diagnosis for EPM caused by S. neurona as a complement to immunodiagnostics. The use of rtPCR in CSF for the detection of S. neurona may improve the diagnostic work-up of neurologic disease suspected horses, especially in animals without previous anti-protozoal treatment.

Validation of a point-of-care polymerase chain reaction assay for detection of Streptococcus equi subspecies equi in rostral nasal swabs from horses with suspected strangles

This study aimed to validate a point-of-care polymerase chain reaction (PCR) assay for detection of Streptococcus equi subsp. equi (S. equi) in rostral nasal swabs from horses with suspected acute strangles and to compare the results against the molecular gold standard of quantitative polymerase chain reaction (qPCR). Two hundred thirty-two individual swabs of rostral nasal passages were characterized by qPCR as S. equi positive, S. equi subsp. zooepidemicus (S. zooepidemicus) positive, or S. equi and S. zooepidemicus negative. The specificity and sensitivity of the point-of-care PCR assay were 89% and 84%, respectively. The limits of detection of the qPCR assay and the point-of-care PCR analyzer were 3 and 277 eqbE target genes of S. equi, respectively. Overall agreement and short turnaround time make the point-of-care PCR assay a potential molecular diagnostic platform that will enhance the capability of equine veterinarians to timely support a diagnosis of strangles and institute proper biosecurity protocols.

The Accuracy of Serum Amyloid A in Determining Early Inflammation in Horses After Long-Distance Transportation by Air

Transportation of sporthorses increases their susceptibility to infectious diseases. Before, caretakers relied on rectal temperature together with their clinical impression to detect travel-associated infections. This study's aim was to assess and compare serum amyloid A (SAA) to rectal temperature as an indicator of early inflammation in sporthorses after air transportation. One hundred and twenty-two Warmblood horses were followed during the Longines Global Champions Tour 2016 to three destinations where the horses flew to compete. Clinical health checks and SAA measurements were performed before flying, upon arrival (0 hours), and 24 hours postarrival. Serum amyloid A was tested using a stall-side lateral flow immunoassay. Rectal temperature was measured twice a day using a commercially available digital thermometer. An SAA cutoff value of 23 μg/mL measured 24 hours postarrival was able to correctly distinguish between a healthy and sick horse with a sensitivity and specificity of 93.3% and 91.3%, respectively. Conversely, elevated rectal temperature had a sensitivity of only 3% to distinguish between the two horse groups. Monitoring SAA in traveling sporthorses is a more sensitive indicator of clinical health than monitoring body temperature and may aid in early identification of inflammatory processes.

Investigation of a 24-Hour Culture Step to Determine the Viability of Streptococcus equi Subspecies equi Via Quantitative Polymerase Chain Reaction in Nasal Secretions From Horses With Suspected Strangles

Polymerase chain reaction (PCR)-based detection assays for Streptococcus equi subspecies equi often overestimate the prevalence of samples containing viable organisms. The objective of this study was to determine if viability could be determined using genome quantitation and detection of messenger RNA (mRNA) transcripts for the SeM gene of S. equi in pre- and post-cultured samples. Nasal secretions collected from 42 horses with suspected strangles were tested by culture and by quantitative PCR (qPCR) before and 24 hours after a culture step. Viable S. equi was determined based on the detection of S. equi via culture, the detection of mRNA transcripts for the SeM gene of S. equi by qPCR, and/or an increase in absolute number of SeM target genes of S. equi between pre- and post-cultured samples. Viability was determined in 28/42 samples based on isolation of S. equi (11 samples), the presence of mRNA transcripts for the SeM gene of S. equi (25), and/or an increase in absolute quantitation of the SeM gene of S. equi between pre- and post-culture (17). The overall agreement between culture alone and the three criteria to determine viability was 59%. The overall agreement for the detection of mRNA transcripts and increase in absolute target genes was 88% and 74%, respectively. The combination of mRNA transcripts and increase in absolute target genes was able to determine the viability status in all 42 samples. In the absence of a culture-positive result for S. equi, the determination of viability can be achieved by using molecular strategies applied to samples undergoing a 24-hour culture step.

Detection of Neospora caninum Infection in Aborted Equine Fetuses in Israel

In horses, Neospora caninum and Neospora hughesi have been associated with fetal loss, and neurological disease, respectively. This study investigated the role of Neospora spp. infection in equine abortion in Israel. The presence of anti-Neospora spp. antibodies was evaluated in 31 aborting mares by indirect fluorescent antibody test (IFAT) and the presence of parasite DNA in their aborted fetuses was evaluated by polymerase chain reaction (PCR), using two target loci (ITS1 and Nc5). The seroprevalence found in aborting mares was 70.9% and the prevalence by DNA detection in the aborted fetuses was 41.9%. Transplacental transmission from positive mares to their fetuses was 45.4% (10/22), while 33.3% (3/9) of fetuses of seronegative mares also tested positive for Neospora. The use of two PCR targets improved the sensitivity of parasite detection, and positive samples were identified by sequence analyses as N. caninum. These finding suggest that N. caninum could be a significant cause of abortion in horses, and that transplacental transmission in horses is an important way of transmission of N.caninum. The results presented here demonstrated the necessity to use several tests concurrently, including serological and molecular assays in order to confirm the involvement of Neospora in mare abortions.