Serial use of serologic assays and fecal PCR assays to aid in identification of subclinical Lawsonia intracellularis infection for targeted treatment of Thoroughbred foals and weanlings.
Abstract: 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. Methods: Evaluation study. Methods: 100 foals and weanlings (53 and 47 at farms in which L intracellularis was endemic and nonendemic, respectively). Methods: 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: IPMA appeared to be a useful means of identifying weanlings exposed to L intracellularis.
Publication Date: 2011-06-02 PubMed ID: 21627513DOI: 10.2460/javma.238.11.1482Google Scholar: Lookup
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- Evaluation Study
- Journal Article
Summary
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The research study aimed to evaluate the effectiveness of using a combination of immunoperoxidase monolayer assays (IPMAs) and fecal polymerase chain reaction (PCR) tests, in conjunction with other diagnostic methods, in detecting subclinical Lawsonia intracellularis infections in Thoroughbred foals and weanlings.
Research Methodology
- The study involved 100 foals and weanlings – 53 from a farm where L. intracellularis infection was endemic and 47 from a non-endemic farm.
- Every four weeks, serum from each participant was collected and tested for antibodies to L. intracellularis using an IPMA test.
- Bi-weekly fecal samples were collected and subjected to an L. intracellularis-specific PCR test.
- If either IPMA or PCR tests showed positive results or if the subjects showed clinical signs consistent with equine proliferative enteropathy (EPE), further clinicopathologic testing was performed to decide the treatment plan.
Research Findings
- None of the foals tested positive for the L. intracellularis-specific IPMA test before weaning.
- 60.4% of the weanlings at the endemic farm and 17% at the non-endemic farm tested positive using the IPMA test.
- Only 6 weanlings at the endemic farm tested positive via the fecal PCR test while none at the non-endemic farm did.
- Out of the 32 weanlings with positive IPMA results at the endemic farm, 19 were treated for EPE, of which five exhibited clinical signs of EPE. No weanlings at the non-endemic farm showed clinical signs or were treated for EPE.
Conclusions
- The results suggested that IPMA tests could be a useful tool for identifying weanlings exposed to L. intracellularis especially in endemic areas.
- However, the validity and utility of the fecal PCR tests seemed more questionable given the lower rate of positive results.
- More research is needed to improve understanding of the infection dynamics of L. intracellularis in horse populations, and to develop more sensitive and reliable diagnostic tools.
Cite This Article
APA
Page AE, Slovis NM, Gebhart CJ, Wolfsdorf K, Mapes SM, Pusterla N.
(2011).
Serial use of serologic assays and fecal PCR assays to aid in identification of subclinical Lawsonia intracellularis infection for targeted treatment of Thoroughbred foals and weanlings.
J Am Vet Med Assoc, 238(11), 1482-1489.
https://doi.org/10.2460/javma.238.11.1482 Publication
Researcher Affiliations
- Hagyard Equine Medical Institute, 4250 Iron Works Pike, Lexington, KY 40511.
MeSH Terms
- Animals
- Animals, Newborn
- Antibodies, Bacterial / blood
- Desulfovibrionaceae Infections / diagnosis
- Desulfovibrionaceae Infections / veterinary
- Diagnosis, Differential
- Feces / microbiology
- Female
- Horse Diseases / diagnosis
- Horses
- Lawsonia Bacteria / immunology
- Lawsonia Bacteria / isolation & purification
- Male
- Polymerase Chain Reaction / veterinary
- Serologic Tests / veterinary
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