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Sequential measurement of serum amyloid A concentrations in ill hospitalized neonatal foals.
Abstract: In hospitalized foals, limited data are available on the utility of sequential measurement of SAA concentrations and the value of these data in a clinical setting. Objective: To determine serum amyloid A (SAA) concentrations in ill neonatal foals at multiple timepoints during hospitalization, and to evaluate a potential association with systemic inflammatory response syndrome (SIRS) status, blood culture (BC) result, and survival. Methods: Hospitalized ill foals (n = 90, ≤ 14 days). Methods: In this retrospective study, foals were classified based on SIRS criteria: "SIRS" or "NonSIRS," BC results, and survival. Serum amyloid A concentrations on admission (ADM), day 1 (D1) and day 2 (D2) were compared within and between groups, using nonparametric tests. Results are presented as median (IQR) (effect size; 95% CI). Results: Serum amyloid A concentrations were higher in SIRS than in NonSIRS foals both on ADM (401 mg/L (99; 855) vs 67 mg/L (23; 685), [ES 129, 95% CI, 15-385]), and on D1 (836 mg/L (616; 1240) vs 212 mg/L (69; 890), [ES 501, 95% CI, 121-724]). On D2, but not on ADM, foals with a positive BC had higher SAA (1244 mg/L (757; 2004)) than BC negative foals (153 mg/L (57; 695), [ES 1002; 95% CI, 282-1418]). On D1, but not on ADM, SAA was higher in non-survivors (729 mg/L (469; 1347) than in survivors (323 mg/L (75; 889), [ES 373; 95% CI, 28-651]). Conclusions: Serum amyloid A measurements on D1 and D2 of hospitalization likely reflect both the severity of disease and response to initial treatment. Repeated SAA measurements during hospitalization can aid clinicians in determining severity of disease and can be useful as a prognosticator in ill neonatal foals.
© The Author(s) 2026. Published by Oxford University Press on behalf of the American College of Veterinary Internal Medicine.
Publication Date: 2026-03-06 PubMed ID: 41789548PubMed Central: PMC12963963DOI: 10.1093/jvimsj/aalag035Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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Overview
- This study examined the changes in serum amyloid A (SAA) levels over time in sick newborn foals in the hospital, seeking to understand how these changes relate to inflammation, infection status, and survival outcomes.
Introduction and Objective
- SAA is an acute phase protein that increases in response to inflammation and infection.
- In neonatal foals, it’s important to know if sequential SAA measurements can help evaluate illness severity, guide treatment decisions, and predict outcomes.
- The main objectives were to measure SAA concentrations at multiple timepoints—on admission (ADM), day 1 (D1), and day 2 (D2)—in hospitalized ill foals and assess associations with:
- Systemic inflammatory response syndrome (SIRS) status
- Blood culture (BC) results (indicating bloodstream infection)
- Survival versus non-survival during hospitalization
Methods
- This was a retrospective study including 90 hospitalized foals aged 14 days or younger.
- Foals were categorized based on three criteria:
- SIRS or NonSIRS based on clinical and laboratory parameters.
- Positive or negative blood cultures (presence or absence of bloodstream infection).
- Outcome: survivor or non-survivor during hospitalization.
- SAA concentrations were measured at three timepoints: admission (ADM), day 1 (D1), and day 2 (D2).
- Statistical analysis involved nonparametric tests comparing SAA levels within and between groups, reporting medians, interquartile ranges (IQR), effect sizes (ES), and 95% confidence intervals (CI).
Key Results
- SAA and SIRS status:
- On admission (ADM), foals with SIRS had significantly higher SAA (median 401 mg/L) compared to NonSIRS foals (67 mg/L).
- On Day 1 (D1), this difference remained with even higher SAA in SIRS foals (836 mg/L vs. 212 mg/L).
- SAA and blood culture results:
- At admission, SAA levels were not significantly different between foals with positive and negative blood cultures.
- On Day 2 (D2), foals with positive blood cultures had markedly higher SAA (1244 mg/L) compared to those with negative cultures (153 mg/L), suggesting delayed or ongoing infection response.
- SAA and survival:
- On Day 1 (D1), non-survivors showed significantly higher SAA concentrations (729 mg/L) than survivors (323 mg/L), indicating higher systemic inflammation in fatal cases.
- No significant differences in SAA at admission were observed based on survival.
Conclusions and Clinical Implications
- Sequential SAA measurements provide valuable information on the severity and progression of illness in hospitalized neonatal foals.
- Elevated SAA on Day 1 and Day 2 correlates with SIRS, bloodstream infection, and poorer outcomes.
- Because SAA changes may lag behind clinical signs and blood culture positivity, multiple measurements over time are useful for tracking response to treatment.
- Clinicians can use repeated SAA testing as a prognostic tool to stratify risk, monitor disease severity, and potentially guide therapeutic decisions in ill neonatal foals.
- This approach enhances the clinical utility of SAA beyond a single measurement at admission, emphasizing the importance of dynamic monitoring during hospitalization.
Cite This Article
APA
van den Brom-Spierenburg AJ, Siegers EW, Westermann CM, Vernooij JCM, Sloet van Oldruitenborgh-Oosterbaan MM, Theelen MJP.
(2026).
Sequential measurement of serum amyloid A concentrations in ill hospitalized neonatal foals.
J Vet Intern Med, 40(2), aalag035.
https://doi.org/10.1093/jvimsj/aalag035 Publication
Researcher Affiliations
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
- Department Population Health Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
- Department of Clinical Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, the Netherlands.
MeSH Terms
- Animals
- Horses
- Serum Amyloid A Protein / analysis
- Serum Amyloid A Protein / metabolism
- Horse Diseases / blood
- Horse Diseases / mortality
- Animals, Newborn / blood
- Retrospective Studies
- Systemic Inflammatory Response Syndrome / veterinary
- Systemic Inflammatory Response Syndrome / blood
- Systemic Inflammatory Response Syndrome / mortality
- Female
- Male
- Hospitalization
Conflict of Interest Statement
The authors declare no conflicts of interest. Serum amyloid A test kits were partly funded by Vrienden Diergeneeskunde. The funding organization was not involved in the design, execution, or reporting of this study.
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