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PubMed | University of Perugia, Private Practitioner and Maxwell uck Equine Research Center
Type: Journal Article | Journal: Veterinary microbiology | Year: 2014

In recent years, there has been increasing evidence of the potential pathogenic significance of equine gammaherpesviruses in the horse. In humans, cattle and mice, gammaherpesviruses have already been associated with uterine infection. The aim of the present study was to investigate the presence of gammaherpesviruses in uterine flushings of mares with reproductive problems and to evaluate if there was a possible statistical association with clinical and laboratory findings in these cases. A total of 80 uterine flushings were collected from 61 mares with different reproductive problems and these were tested for equine herpesviruses (EHV) 1-5 by PCR. In the case of each mare in the study, the age, history of infertility, presence of anatomical defects in the reproductive tract, presence of systemic or local disease at time of sampling, phase in the oestrous cycle, post-partum interval, nature of uterine lavage performed (low versus large volume lavage), cytological and bacteriological examination results from the uterine flushing, and PCR herpesvirus results were recorded. Univariate analysis and multivariable logistic regression models were used to identify possible statistical associations and risk factors. Nine out of 61 mares (14.7%) had EHV-5 DNA in their uterine flushings. Co-infections with EHV-1 and EHV-2 were present in two cases. Of all the variables analyzed, only the cytological examination findings were associated with EHV-5 PCR positive results, both on univariate and multivariable analysis, especially in cases with an inflammation score of 3. It is postulated that presence of EHV-5 infection in the non-pregnant uterus may have a role to play in reproductive dysfunction and have a negative consequence on the pregnant uterus. Additional studies involving both healthy mares and mares with reproductive problems need to be performed, however, to elucidate whatever role equine gammaherpesviruses may play in the reproductive tract. This would be very worthwhile, since reproductive problems can have a significant impact on the equine breeding industry. Gaining a greater understanding of its causes could lead to new approaches for prevention and treatment.


Campos J.R.,Maxwell uck Equine Research Center | Breheny P.,University of Kentucky | Breheny P.,University of Iowa | Araujo R.R.,University of Sao Paulo | And 4 more authors.
Theriogenology | Year: 2014

Equine arteritis virus (EAV) is the causal agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids. Some strains of EAV can cause fever, leukopenia, and dependent edema of the limbs, scrotum, and preputium in the acutely infected stallion. We hypothesized that fever and scrotal edema observed during the acute phase of the infection, but not the presence of EAV, have an adverse effect on semen quality. A group of seven stallions were intranasally inoculated with the Kentucky 84 (KY84) strain of EAV. Stallions were monitored for clinical signs of EVA until 42days postinoculation (dpi). Semen was collected every other day for the first 15days and 2 times a week up to 79dpi. Additional samples were collected at 147, 149, and 151dpi. Semen from each stallion was evaluated on the basis of motion characteristics, total number of spermatozoa, membrane integrity, and morphology. Virus infectivity titers were determined in RK-13 cells. Significant decreases in sperm quality were observed between 9 and 76dpi. LOWESS (locally weighted scatterplot smoothing) curves for each horse were fit and integrated to quantify spermatozoa exposure to fever, virus, and edema over a period of 67days before each ejaculation. Linear mixed models were then fit to isolate the effects of each factor on semen quality. Scrotal edema and fever were found to exert independent effects on all the semen quality parameters (P≤0.002), whereas virus seems to exert little to no direct effect, as virus titers remained high long after semen quality returned to baseline. © 2014 Elsevier Inc.


PubMed | University of Kentucky, Maxwell uck Equine Research Center and University of Sao Paulo
Type: Journal Article | Journal: Theriogenology | Year: 2014

Equine arteritis virus (EAV) is the causal agent of equine viral arteritis (EVA), a respiratory and reproductive disease of equids. Some strains of EAV can cause fever, leukopenia, and dependent edema of the limbs, scrotum, and preputium in the acutely infected stallion. We hypothesized that fever and scrotal edema observed during the acute phase of the infection, but not the presence of EAV, have an adverse effect on semen quality. A group of seven stallions were intranasally inoculated with the Kentucky 84 (KY84) strain of EAV. Stallions were monitored for clinical signs of EVA until 42 days postinoculation (dpi). Semen was collected every other day for the first 15 days and 2 times a week up to 79 dpi. Additional samples were collected at 147, 149, and 151 dpi. Semen from each stallion was evaluated on the basis of motion characteristics, total number of spermatozoa, membrane integrity, and morphology. Virus infectivity titers were determined in RK-13 cells. Significant decreases in sperm quality were observed between 9 and 76 dpi. LOWESS (locally weighted scatterplot smoothing) curves for each horse were fit and integrated to quantify spermatozoa exposure to fever, virus, and edema over a period of 67 days before each ejaculation. Linear mixed models were then fit to isolate the effects of each factor on semen quality. Scrotal edema and fever were found to exert independent effects on all the semen quality parameters (P 0.002), whereas virus seems to exert little to no direct effect, as virus titers remained high long after semen quality returned to baseline.


Mozzaquatro F.D.,Federal University of Santa Maria | Verstegen J.P.,University of Florida | Douglas R.H.,University of Kentucky | Troedsson M.H.T.,Maxwell uck Equine Research Center | And 3 more authors.
Reproduction in Domestic Animals | Year: 2012

Contents: Ultrasound-guided follicular aspiration was performed in 26 Criollo crossbred mares, followed by the evaluation of ultrasonographic images of the Corpus luteum (CL) that was formed after puncture of follicles of different diameters (Group 25-29mm; Group 30-35mm and Group >35mm). Serum progesterone (P4) concentrations were measured to determine CL function. The size of the CL was measured and the CL was classified based on the following echoscore: 1- anechoic tissue; 2- poorly defined luteal structure with low echogenicity; 3- echogenicity analogous to a luteal structure. The proportion of aspirated follicles that formed a functional CL (based on P4 concentration) 8days after aspiration was 57.1% (4/7; CL size 25-29mm), 75.0% (6/8; CL size 30-35mm) and 72.7% (8/11; CL size >35mm), respectively (p>0.05). The echographic scores of aspirated follicles (indicating the presence or absence of a CL) were consistent with serum P4 concentrations (p<0.0001). Of 26 aspirations, 18 resulted in luteal function confirmed by increased progesterone concentrations ([P4]>1.0ng/ml); 17 of these mares (94.4%) had an echoscore (2-3) compatible with luteinization (p=0.0372). Eight days after aspiration, serum [P4]>2.0ng/ml was associated with high (p=0.0056) CL echoscore (3) in 15 of 17 mares (88.2%). The echoscore used in this study was valuable as a screening test to detect the presence of a functional CL after aspiration. An echoscore of 3 served as a practical and efficient method to confirm luteinization. © 2011 Blackwell Verlag GmbH.


Sanz M.G.,Maxwell uck Equine Research Center | Villarino N.,Washington State University | Ferreira-Oliveira A.,Maxwell uck Equine Research Center | Horohov D.W.,Maxwell uck Equine Research Center
Veterinary Immunology and Immunopathology | Year: 2015

Rhodococcus equi is a common cause of pneumonia in young foals worldwide and has considerable economic effects on the global equine industry. Despite ongoing efforts, no vaccine is currently available to prevent rhodococaal pneumonia. This is due, in part, to an incomplete understanding of the protective immune response to this bacterium. While antibodies to VapA, a lipoprotein produced by virulent R. equi, are useful in differentiating antibody production in response to pathogenic versus non-pathogenic strains, the significance of the humoral response of foals to this lipoprotein remains poorly defined. The objectives of this study were to evaluate changes in VapA-specific IgG and IgG subclasses after exposure and infection of neonatal foals. Experimental foals included those challenged with R. equi at 1 (n = 18), 2 (n = 4) and 3 (n = 6) weeks of age. Confirmed naturally infected (n = 7) and not infected (n = 3) foals were also included. All foals were bled 24. h after birth and weekly thereafter for a period of 8 weeks. Antibody changes over time were evaluated.Following birth, VapA-specific IgGs significantly (p < 0.05) decreased over time in all foals as a result of normal decay of passively transferred antibodies. Both VapA-specific IgGa and IgG(T) significantly increased (p < 0.05) after experimental challenge, however, the rise in IgG(T) occurred earlier. Only a significant (p < 0.05) increase in VapA-specific IgG(T) over time was seen after natural infection. Whether VapA-specific IgG(T) can be used to differentiate rhodococcal from other pneumonias requires further investigation under field conditions. © 2015 Elsevier B.V.


PubMed | Washington State University and Maxwell uck Equine Research Center
Type: Journal Article | Journal: Veterinary immunology and immunopathology | Year: 2015

Rhodococcus equi is a common cause of pneumonia in young foals worldwide and has considerable economic effects on the global equine industry. Despite ongoing efforts, no vaccine is currently available to prevent rhodococaal pneumonia. This is due, in part, to an incomplete understanding of the protective immune response to this bacterium. While antibodies to VapA, a lipoprotein produced by virulent R. equi, are useful in differentiating antibody production in response to pathogenic versus non-pathogenic strains, the significance of the humoral response of foals to this lipoprotein remains poorly defined. The objectives of this study were to evaluate changes in VapA-specific IgG and IgG subclasses after exposure and infection of neonatal foals. Experimental foals included those challenged with R. equi at 1 (n=18), 2 (n=4) and 3 (n=6) weeks of age. Confirmed naturally infected (n=7) and not infected (n=3) foals were also included. All foals were bled 24h after birth and weekly thereafter for a period of 8 weeks. Antibody changes over time were evaluated. Following birth, VapA-specific IgGs significantly (p<0.05) decreased over time in all foals as a result of normal decay of passively transferred antibodies. Both VapA-specific IgGa and IgG(T) significantly increased (p<0.05) after experimental challenge, however, the rise in IgG(T) occurred earlier. Only a significant (p<0.05) increase in VapA-specific IgG(T) over time was seen after natural infection. Whether VapA-specific IgG(T) can be used to differentiate rhodococcal from other pneumonias requires further investigation under field conditions.


Morrell J.,Swedish University of Agricultural Sciences | Timoney P.,Maxwell uck Equine Research Center | Klein C.,Maxwell uck Equine Research Center | Shuck K.,Maxwell uck Equine Research Center | And 2 more authors.
Reproduction in Domestic Animals | Year: 2013

Several countries have adopted strategies for preventing and/or controlling equine viral arteritis based on vaccination and restricting the breeding activities of carrier stallions. However, in some cases, carrier stallions are only identified after they have transmitted virus to a mare. Therefore, a mechanism for separating virus from spermatozoa in the semen of carrier stallions would facilitate control measures for preventing disease transmission. In this study, the use of several modifications of single-layer centrifugation (SLC, SLC with an inner tube and double SLC) through Androcoll-E, a species-specific colloid were evaluated for their ability to separate spermatozoa from virus in ejaculates from carrier stallions. The three types of SLC significantly reduced the virus titre in fresh semen at 0 h and in stored semen at 24 h (p < 0.001) but did not completely eliminate the virus. Sperm motility parameters such as total motility and progressive motility were significantly increased after colloid centrifugation, whereas curvilinear velocity and amplitude of lateral head deviation were decreased, and the remainder (straight line velocity, average path velocity, straightness, linearity, wobble and beat cross-frequency) were not significantly affected by the processing. Although virus titres were reduced in the SLC samples, significant levels of infectivity still remained, especially in stallions shedding large amounts of virus. It remains to be determined whether SLC-processed sperm samples from stallions shedding low virus titres retain sufficient equine arteritis virus to cause infection in mares through artificial insemination. © 2012 Blackwell Verlag GmbH.


PubMed | University of Iceland, Veterinary Diagnostic Laboratory, Maxwell uck Equine Research Center and University of Georgia
Type: Journal Article | Journal: Equine veterinary journal | Year: 2015

Rhodococcus equi (Rhodococcus hoagii/Prescottella equi) is a common cause of foal pneumonia, but its diagnosis remains a challenge for equine veterinarians. While the VapA-specific (virulence-associated protein A) immunoglobulinG (IgG) enzyme-linked immunosorbent assay (ELISA) has low sensitivity and specificity for detecting pneumonic foals, little is known about VapA-specific IgG subclasses.To evaluate the performance of VapA-specific ELISA for IgG and its subclasses IgGa, IgGb and IgG(T) in the early diagnosis of pneumonia caused by R.equi.Assay validation followed by assessment of diagnostic performance using archived samples from animals of known status.Serum samples from exposed (n = 125) and nonexposed adult horses (n = 10) and from experimentally challenged and naturally infected foals were used for ELISA validation. Post mortem and tissue culture records of the last 24years from the Institute for Experimental Pathology at the University of Iceland in Keldur, Iceland laboratory were evaluated to confirm the absence of R.equi cases in Iceland. The diagnostic performance of VapA-specific IgG and its subclasses was evaluated using banked serum samples from pneumonic (n = 21) and healthy foals (n = 80). To evaluate each IgG assay, a cut-off value was selected based on receiver operating characteristic curve analysis and used to calculate sensitivity and specificity. The intra- and interassay coefficients of variation were calculated for each ELISA.Using sera from Iceland, where R.equi infection has not been reported, the VapA-specific IgG ELISA differentiated exposed from nonexposed horses. When used to identify infected foals, VapA-specific IgG, IgGa and IgGb had no diagnostic value. In contrast, IgG(T) had high sensitivity and specificity.Horses from Iceland are not exposed to VapA(+) R.equi and can serve as negative controls. VapA-specific IgG subclasses, with the exception of IgG(T), are poor predictors of disease. Further investigation on the use of IgG(T) as a diagnostic tool in field conditions is needed.


Sanz M.G.,Maxwell uck Equine Research Center | Oliveira A.F.,Maxwell uck Equine Research Center | Page A.,Maxwell uck Equine Research Center | Horohov D.W.,Maxwell uck Equine Research Center
Veterinary Record | Year: 2014

Rhodococcus equi is the most common cause of pneumonia in young foals. A vaccine is not available and the use of R equi-specific hyperimmune plasma (HIP) is common. Despite its widespread use, the efficacy of HIP in preventing disease remains controversial. The objectives of this study were (1) to evaluate the virulence associate protein A (VapA)-specific IgG and IgG subclasses in commercially available R equi HIP and (2) to evaluate serum VapA-specific IgG and IgG subclasses in foals following administration of commercial R equi HIP. Three different lots from four commercial R equi HIP were sampled. VapA-specific IgG and IgG subclasses were evaluated in all samples using an ELISA. Serum was collected from newborn foals either after commercial R equi HIP was administered (n=97) or not (n=70). Serum was also collected from each mare. Administration of HIP significantly (P<0.001) increased VapA-specific IgGs in recipient foals, however, there was a marked variation in VapA-specific IgGs in foals receiving the same product. VapA-specific IgGs were significantly different (P<0.001) between products and varied between lots, with coefficients of variation ranging from 17 to 123 per cent. These results may explain previously reported disparities in HIP efficacy.


PubMed | Maxwell uck Equine Research Center
Type: Journal Article | Journal: The Veterinary record | Year: 2014

Rhodococcus equi is the most common cause of pneumonia in young foals. A vaccine is not available and the use of R equi-specific hyperimmune plasma (HIP) is common. Despite its widespread use, the efficacy of HIP in preventing disease remains controversial. The objectives of this study were (1) to evaluate the virulence associate protein A (VapA)-specific IgG and IgG subclasses in commercially available R equi HIP and (2) to evaluate serum VapA-specific IgG and IgG subclasses in foals following administration of commercial R equi HIP. Three different lots from four commercial R equi HIP were sampled. VapA-specific IgG and IgG subclasses were evaluated in all samples using an ELISA. Serum was collected from newborn foals either after commercial R equi HIP was administered (n=97) or not (n=70). Serum was also collected from each mare. Administration of HIP significantly (P<0.001) increased VapA-specific IgGs in recipient foals, however, there was a marked variation in VapA-specific IgGs in foals receiving the same product. VapA-specific IgGs were significantly different (P<0.001) between products and varied between lots, with coefficients of variation ranging from 17 to 123 per cent. These results may explain previously reported disparities in HIP efficacy.

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