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Equine veterinary journal2026; doi: 10.1002/evj.70207

Bacteremia in horses undergoing routine dental prophylaxis: Before, during, and after the procedure.

Abstract: Transient bacteremia after dental procedures is well-documented in the literature, but the prevalence and clinical significance in horses remains largely unexplored. Objective: To assess whether routine dental prophylaxis in clinically healthy horses is associated with detection of bacteria in blood, using culture and 16S rDNA sequencing. Our central hypothesis is that a percentage of horses would demonstrate detectable but transient bacteremia in the immediate post-procedural period following dental prophylaxis. Methods: Prospective, observational study. Methods: Venous blood samples from 20 horses without evidence of significant dental disease were collected before, immediately after, 30 min, 60 min, and 24 h post-procedure and submitted for routine aerobic and anaerobic bacterial culture and 16S rDNA sequencing. Results: Data were analysed for normality by Shapiro-Wilk and Kruskal-Wallis analysis of variance (ANOVA) on ranks was performed on non-normally distributed data. Sixteen of twenty horses had positive blood cultures at one or more time points with no significant difference in the proportion of positive blood cultures among time points but differential abundance analysis identified eight bacterial families with increased and three with decreased relative abundance at one or more post-procedural time points compared to baseline. Several of these families have been associated with the equine oral or gastrointestinal microbiota, whereas others are commonly reported in plant soil and reagent-associated communities. Conclusions: Small sample size, lack of age-matched controls, absence of technical negative controls, and low-biomass nature of blood samples limit interpretation. Conclusions: Culturable bacteria and bacterial DNA were detected from blood samples of clinically healthy horses before and after routine dental prophylaxis, though overall culture positivity and community diversity remained stable. Differential abundance analyses identified subtle post-procedural changes in low-abundance taxa; however, without negative controls, these findings may reflect biological variation or contamination and should be interpreted cautiously.
© 2026 The Author(s). Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2026-07-26 PubMed ID: 42503025DOI: 10.1002/evj.70207Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Research Overview

  • This study investigated whether routine dental cleaning in healthy horses leads to bacteria entering the bloodstream (bacteremia).
  • Researchers collected and analyzed blood samples before and after dental prophylaxis using bacterial culture and genetic sequencing to check for bacteria presence and changes.

Background and Objective

  • Transient bacteremia—temporary presence of bacteria in the blood—is known after dental procedures in humans and some animals.
  • However, for horses undergoing routine dental care, the frequency and clinical importance of bacteremia had not been clearly studied.
  • The objective was to determine if routine dental prophylaxis in healthy horses leads to detectable bacteria in blood samples immediately after and at various times post-procedure.
  • The central hypothesis was that some horses would show short-lived bacteremia after receiving dental cleaning.

Methods

  • Study design: A prospective, observational study was conducted.
  • Subjects: 20 clinically healthy horses without significant dental disease were included.
  • Sampling: Venous blood samples were taken at five time points:
    • Before the procedure (baseline)
    • Immediately after the dental cleaning
    • 30 minutes post-procedure
    • 60 minutes post-procedure
    • 24 hours post-procedure
  • Analytical techniques:
    • Bacterial cultures were performed under both aerobic and anaerobic conditions to identify live, culturable bacteria.
    • 16S rDNA sequencing was used to detect and identify bacterial DNA, allowing detection of a broader range of bacteria including those not easily cultured.
  • Statistical analysis:
    • Shapiro-Wilk test was used to assess normality of data.
    • Kruskal-Wallis ANOVA on ranks was applied to non-normally distributed data.
    • Differential abundance analyses compared bacterial community profiles at post-procedure time points versus baseline.

Results

  • Culture positivity: 16 out of 20 horses had positive blood cultures at one or more time points.
  • Time point comparison: There was no statistically significant difference in the proportion of positive cultures between pre- and post-procedure time points.
  • Bacterial community changes: Differential abundance analysis revealed:
    • Eight bacterial families increased in relative abundance at one or more post-procedure time points compared to baseline.
    • Three bacterial families decreased in relative abundance after the procedure.
  • Origin of bacteria:
    • Some bacterial families detected are common in equine oral or gastrointestinal microbiota, possibly reflecting transient bacteremia or normal biology.
    • Other families are typically found in soil or are known contaminants from reagents used in laboratory processes, raising concerns about contamination.

Conclusions and Limitations

  • Bacteria and bacterial DNA could be detected in the blood of clinically healthy horses both before and after routine dental cleaning, indicating that the presence of bacteria in blood is not uncommon even without active dental disease or recent procedures.
  • Overall, the rates of culture positivity and the diversity of bacterial communities remained stable across time points, suggesting no major increase in bacteremia due to the dental procedures.
  • Subtle changes in low-abundance bacterial taxa were observed post-procedure, but interpreting these changes is complicated due to:
    • Small sample size limiting statistical power and generalizability.
    • Lack of age-matched controls to rule out confounding variables.
    • Absence of technical negative controls in sequencing, making it difficult to distinguish genuine biological signals from contamination, especially given that blood is a low-biomass sample prone to contamination artifacts.
  • Therefore, while transient bacteremia may occur in some horses after dental cleaning, these findings should be interpreted cautiously, and future studies with better controls and larger cohorts are needed to clarify the clinical relevance.

Cite This Article

APA
Dockery A, Whitfield-Cargile C, Knopp V, Sinay T. (2026). Bacteremia in horses undergoing routine dental prophylaxis: Before, during, and after the procedure. Equine Vet J. https://doi.org/10.1002/evj.70207

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Dockery, Allison
  • Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
Whitfield-Cargile, Canaan
  • Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
Knopp, Vanessa
  • Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
Sinay, Taylor
  • Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.

Grant Funding

  • The University of Georgia

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