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- Author or Editor: Nicola Pusterla x
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Abstract
Objective—To evaluate the effectiveness of a commercial conventional blood culture system (BCS), a commercial resin-containing BCS, and a commercial lysis-centrifugation–based BCS for the recovery of Escherichia coli from equine blood samples inoculated with that organism.
Sample Population—Samples of blood obtained from a clinically normal horse that were inoculated with E coli.
Procedures—Blood samples were aseptically collected and inoculated with an E coli specimen (50 CFUs/mL) that had been previously isolated from a foal with sepsis. Subsequently, samples were spiked with gentamicin at a concentration of 30 μg/mL, and 10 mL of each mixture was inoculated into 1 bottle or tube of each BCS. Samples were processed and incubated according to the manufacturer's guidelines and inoculated onto 5% sheep blood agar plates. Plated samples were examined macroscopically at regular intervals for as long as 72 hours. Detection of E coli and time to detection were recorded for each medium.
Results—Detection frequency of E coli was significantly greater by use of the resin-containing BCS (14/23 bottles) than that achieved by use of the conventional BCS (7/23 bottles) or the lysis-centrifugation–based BCS (0/10 tubes). Mean detection time (6 hours after plating) did not differ between the BCS with conventional medium and the BCS with resincontaining medium.
Conclusions and Clinical Relevance—Results suggest that a BCS with resin-containing medium may provide clinical benefit in the successful recovery of E coli from the blood of foals with sepsis that have been previously administered gentamicin.
Abstract
Objective—To determine gene expression of selected molecular markers (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, IL-6, IL-8, IL-10, procalcitonin [PCT], and transforming growth factor [TGF]-β) in the blood of healthy and sick foals.
Animals—28 sick foals without sepsis, 21 foals with sepsis, and 21 healthy foals.
Procedures—Total RNA was extracted from blood samples and converted into complementary DNA (cDNA). Gene expression was measured for the molecular markers by use of real-time PCR assay, and final quantitation was performed with the comparative threshold cycle method.
Results—Samples from all foals yielded transcription for all markers. Expression of TNF-α and TGF-β was significantly lower and that of IL-8 significantly greater in the sick-nonseptic and septic groups, compared with the healthy group. No significant difference in expression of IL-1β, IL-6, and PCT was found between the healthy group and the 2 sick groups. Expression of IL-10 was significantly greater in nonsurvivors, compared with survivors.
Conclusions and Clinical Relevance—The cytokine profile in foals with sepsis may suggest an immunosuppressive state. Expression of IL-10 may be a marker for identification of foals with a guarded prognosis.
Abstract
Objective—To determine concentrations of α-tocopherol in serum and CSF of healthy horses following administration of supplemental vitamin E in feed.
Animals—10 healthy adult horses.
Procedures—Horses were allocated to receive supplemental d-α-tocopherol (1,000 U/d [group A; n = 5] or 10,000 U/d [group B; 5]) in feed for 10 days. Blood samples were collected before (baseline), during, and at intervals for 10 days after discontinuation of vitamin E administration for assessment of serum α-tocopherol concentration. Cerebrospinal fluid samples were collected prior to and 24 hours after cessation of vitamin E administration. α-Tocopherol concentrations in serum and CSF samples were analyzed via high-performance liquid chromatography; changes in those values during the treatment period were compared between groups, and the relationship of serum and CSF α-tocopherol concentrations was evaluated.
Results—In both groups, serum α-tocopherol concentration increased significantly from baseline during vitamin E administration; values in group B were significantly greater than those in group A during and after treatment. At the end of vitamin E administration, CSF α-tocopherol concentration was not significantly greater than the baseline value in either group; however, the increase in CSF concentration was significant when the group data were combined and analyzed. Serum and CSF α-tocopherol concentrations were significantly correlated at baseline for all horses, but were not strongly correlated after 10 days of vitamin E administration.
Conclusions and Clinical Relevance—In healthy horses, daily oral administration of supplemental vitamin E in feed resulted in increases in serum and CSF α-tocopherol concentrations.
Abstract
Objective—To determine susceptibility of cattle to infection with Ehrlichia equi and the agent of human granulocytic ehrlichiosis (HGE).
Design—Experimental disease and prevalence survey.
Animals—6 cattle, 2 horses, and 2,725 serum samples from healthy cattle.
Procedure—2 cattle and 1 horse were inoculated with E equi, 2 cattle and 1 horse were inoculated with the HGE agent, and 2 cattle served as sham-inoculated controls; inoculated animals were evaluated via clinical, hematologic, serologic, and real-time polymerase chain reaction tests. Prevalence of antibodies against E equi in 2,725 healthy cattle was determined by use of an indirect immunofluorescent technique.
Results—No abnormal clinical or hematologic findings or inclusion bodies within granulocytes were observed in the cattle after inoculation, and results of all polymerase chain reaction tests were negative. Seroconversion in inoculated cattle developed 10 to 12 days after inoculation (reciprocal titers, 160). Both horses developed clinical signs of ehrlichiosis. Five of 2,725 (0.18%) cattle were seropositive for E equi, with titers ranging from 20 to 80. All seropositive cattle originated from the same tick-rich region in the Sierra Nevada foothills.
Conclusions and Clinical Relevance—Results suggest that cattle are not susceptible to infection with E equi or the agent of HGE and that prevalence of exposure to E equi in healthy cattle is low. Therefore, E equi and the agent of HGE are likely of negligible importance for cattle in North America. (J Am Vet Med Assoc 2001;218:1160–1162)
Abstract
Case Description—A 4-month-old American Paint Horse colt was evaluated because of acute onset of ataxia, left-sided head tilt, and fever and a recently noticed heart murmur. Upper respiratory tract infection caused by Streptococcus equi subsp equi had been diagnosed at 3 months of age.
Clinical Findings—Hematologic abnormalities included leukocytosis, mature neutrophilia, monocytosis, and mild anemia. Analysis of a CSF sample revealed high total protein concentration and total nucleated cell count; nucleated cells consisted mainly of degenerate neutrophils. Results of a real-time PCR assay were positive for S equi subsp equi, and a diagnosis of S equi subsp equi meningoencephalomyelitis was made.
Treatment and Outcome—Treatment included administration of potassium penicillin and fluids, but the foal developed uroperitoneum and was subsequently euthanized. Postmortem examination revealed meningoencephalomyelitis, and S equi subsp equi was cultured from a brain aspirate. Additional findings included suppurative cystitis with rupture and neutrophilic myocarditis.
Clinical Relevance—Findings suggest that S equi subsp equi meningoencephalomyelitis should be considered in the differential diagnosis for foals with neurologic signs that have a history of strangles or exposure to affected horses.
Abstract
Objective—To determine gene transcription for cytokines in nucleated cells in CSF of horses without neurologic signs or with cervical stenotic myelopathy (CSM), West Nile virus (WNV) encephalitis, equine protozoal myeloencephalitis (EPM), or spinal cord trauma.
Animals—41 horses (no neurologic signs [n = 12], CSM [8], WNV encephalitis [9], EPM [6], and spinal cord trauma [6]).
Procedures—Total RNA was extracted from nucleated cells and converted into cDNA. Gene expression was measured by use of real-time PCR assay and final quantitation via the comparative threshold cycle method.
Results—Cytokine genes expressed by nucleated cells of horses without neurologic signs comprised a balance between proinflammatory tumor necrosis factor-α (TNF-α), anti-inflammatory cytokines (interleukin [IL]-10 and transforming growth factor [TGF]-β), and Th1 mediators (interferon [IFN]-γ). Cells of horses with CSM mainly expressed genes for TNF-α, TGF-β, and IL-10. Cells of horses with WNV encephalitis mainly expressed genes for IL-6 and TGF-β. Cells of horses with EPM mainly had expression of genes for IL-6, IL-8, IL-10, TNF-α, IFN-γ, and TGF-β. Cells from horses with spinal cord trauma had expression mainly for IL-6; IFN-γ; TGF-β; and less frequently, IL-2, IL-10, and TNF-α. Interleukin-8 gene expression was only detected in CSF of horses with infectious diseases.
Conclusions and Clinical Relevance—Despite the small number of CSF samples for each group, results suggest distinct gene signatures expressed by nucleated cells in the CSF of horses without neurologic signs versus horses with inflammatory or traumatic neurologic disorders.
Abstract
OBJECTIVE To describe the general seroprevalence of anti-Sarcocystis neurona and anti-Neospora hughesi antibodies among healthy equids by use of indirect fluorescent antibody tests and determine potential risk factors for seropositivity.
DESIGN Cross-sectional study.
SAMPLE Whole blood samples collected from 5,250 equids (1 sample/animal) across 18 states in the United States during October 2013.
PROCEDURES Information regarding potential risk factors (geographic region, breed, primary use, sex, and age) was collected along with the blood samples. For each equid, an indirect fluorescent antibody test was used to determine serum titers of antibody against each of the 2 protozoal parasites. Mixed-effects logistic regression models were created to determine ORs for seropositivity.
RESULTS The overall seroprevalence of anti-S neurona and anti-N hughesi antibodies in the tested equids was 78% and 34%, respectively. Of the equids, 31% were seropositive and 18% were seronegative for antibodies against both parasites. Factors associated with equids being seropositive for anti-S neurona antibodies were residence in the South, warmblood breed, and age > 5 years. Seroprevalence of anti-N hughesi antibodies did not differ among equids in different states across the country, but warmblood breed and age > 5 years were associated with seropositivity.
CONCLUSIONS AND CLINICAL RELEVANCE With regard to risk factors for S neurona and N hughesi exposure and antibody response among tested equids, older age was not unexpected; however, the influences of warmblood breed and geographic location on seropositivity for anti-S neurona antibody but not for anti-N hughesi antibody deserve further investigation.
Abstract
Objective—To evaluate metaphylactic RNA interference to prevent equine herpesvirus type 1 (EHV-1) infection in experimental herpesvirus myeloencephalopathy in horses and to determine whether horses infected with a neuropathogenic strain of the virus that develop equine herpesvirus myeloencephalopathy (EHM) have differences in viremia.
Animals—13 seronegative horses.
Procedures—EHV-1 strain Ab4 was administered intranasally on day 0, and small interfering RNAs (siRNAs [EHV-1 specific siRNAs {n = 7} or an irrelevant siRNA {6}]) were administered intranasally 24 hours before and 12, 24, 36, and 48 hours after infection. Physical and neurologic examinations, nasal swab specimens, and blood samples were collected for virus isolation and quantitative PCR assay. Data from the study were combined with data from a previous study of 14 horses.
Results—No significant difference was detected in clinical variables, viremia, or detection of EHV-1 in nasal swab specimens of horses treated with the EHV-1 targeted siRNAs (sigB3-siOri2) versus controls. No significant differences in viremia were detected between horses that developed EHM and those that did not.
Conclusions and Clinical Relevance—Administration of siRNAs targeted against EHV-1 around the time of EHV-1 infection was not protective with this experimental design. Horses infected with the neuropathogenic EHV-1 strain Ab4 that developed EHM did not have a more pronounced viremia.
Abstract
Objective—To assess the serial use of serum immunoperoxidase monolayer assays (IPMAs) and fecal PCR assays, combined with other diagnostic methods, to identify subclinical Lawsonia intracellularis infections for targeted treatment of Thoroughbred foals and weanlings at farms in which the pathogen was endemic or nonendemic.
Design—Evaluation study.
Animals—100 foals and weanlings (53 and 47 at farms in which L intracellularis was endemic and nonendemic, respectively).
Procedures—Serum was collected every 4 weeks and tested via IPMA, for antibodies against L intracellularis. Fecal samples were collected every 2 weeks and tested by use of an L intracellularis–specific PCR assay. When results for IPMAs or PCR assays were positive or clinical signs compatible with equine proliferative enteropathy (EPE) were detected, clinicopathologic testing was performed to determine treatment.
Results—No foals had positive results for the L intracellularis–specific IPMA until after weaning; 32 of 53 (60.4%) weanlings at the farm in which L intracellularis was endemic and 8 of 47 (170%) at the farm in which L intracellularis was nonendemic had positive IPMA results, whereas the number of weanlings that tested positive via fecal PCR assays at those farms was 6 and 0, respectively. Nineteen of 32 weanlings with positive IPMA results at the farm in which L intracellularis was endemic were treated for EPE; 5 of these had clinical signs of EPE. No weanlings at the nonendemic farm had clinical signs of or were treated for EPE.
Conclusions and Clinical Relevance—IPMA appeared to be a useful means of identifying weanlings exposed to L intracellularis.
