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- Author or Editor: Samantha M. Mapes x
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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.
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.
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.
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 , WNV encephalitis , EPM , and spinal cord trauma ).
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.
Objective—To determine the incidence of equine herpesvirus-1 (EHV-1) infection among Thoroughbreds residing on a farm on which the virus was known to be endemic.
Design—Prospective cohort study.
Animals—10 nonpregnant mares, 8 stallions, 16 weanlings, 11 racehorses, and 30 pregnant mares and their foals born during the 2006 foaling season.
Procedures—Blood and nasopharygeal swab samples were collected every 3 to 5 weeks for 9 months, and placenta and colostrum samples were collected at foaling. All samples were submitted for testing for EHV-1 DNA with a PCR assay. A type-specific EHV-1 ELISA was used to determine antibody titers in mares and foals at birth, 12 to 24 hours after birth, and every 3 to 5 weeks thereafter.
Results—Results of the PCR assay were positive for only 4 of the 1,330 samples collected (590 blood samples, 590 nasopharyngeal swab samples, 30 placentas, and 30 colostrum samples), with EHV-1 DNA detected in nasal secretions from 3 horses (pregnant mare, stallion, and racehorse) and in the placenta from 1 mare. Seroconversion was detected in 3 of 27 foals during the first month of life.
Conclusions and Clinical Relevance—Results suggested that there was a low prevalence of EHV-1 infection among this population of Thoroughbreds even though the virus was known to be endemic on the farm and that pregnant mares could become infected without aborting. Analysis of nasopharyngeal swab samples appeared to be more sensitive than analysis of blood samples for detection of EHV-1 DNA.
Objective—To determine the efficacy of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy in weanling foals.
Animals—12 healthy weanling foals.
Procedures—Foals were randomly assigned to a vaccinated, nonvaccinated, or control group. Vaccinated foals received an avirulent porcine L intracellularis frozen-thawed vaccine intrarectally 60 and 30 days prior to experimental challenge. On day 1, vaccinated and nonvaccinated foals were challenged via nasogastric intubation with a virulent heterologous isolate of L intracellularis. Control foals were not challenged. Clinical observation and ultrasonographic evaluation of the small intestine were performed, and body weight, serum concentration of total solids, fecal excretion of L intracellularis, and seroconversion were measured for each foal until day 56. Diseased foals were treated with antimicrobials and supportive care.
Results—None of the 4 vaccinated foals developed clinical disease following challenge with virulent L intracellularis. Three of 4 nonvaccinated foals developed moderate to severe clinical signs compatible with proliferative enteropathy, hypoproteinemia, and thickened small intestinal loops. Vaccinated foals had significantly less fecal shedding of L intracellularis than nonvaccinated foals. Serologic responses between vaccinated and nonvaccinated foals after challenge were similar. Control foals remained clinically unaffected with no evidence of fecal shedding and seroconversion.
Conclusions and Clinical Relevance—Intrarectal administration of a commercial avirulent porcine vaccine against L intracellularis resulted in complete protection against proliferative enteropathy in the foals in this study and may also reduce environmental contamination with the organism on endemic farms.