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Plasma C-reactive protein and interleukin-6 concentrations in foals during health and respiratory disease
Dorothea Hildebrandt1, Monica Venner2, Kelsey A Hart3
1Clinic for Horses, University of Veterinary Medicine Hannover, Hanover, Germany.
Insights
C-reactive protein (CRP) and interleukin-6 (IL-6) are not reliable predictors for diagnosing foal bronchopneumonia. Further research is needed to explore their utility in foal respiratory disease management.
Area of Science:
- Equine medicine
- Veterinary diagnostics
- Neonatal animal health
Background:
- Early diagnosis of foal bronchopneumonia is crucial for preventing severe outcomes.
- C-reactive protein (CRP) and interleukin-6 (IL-6) are established biomarkers for neonatal pneumonia in other species.
- Limited data exists on the efficacy of CRP and IL-6 in diagnosing naturally occurring respiratory diseases in foals.
Purpose of the Study:
- To evaluate C-reactive protein (CRP) and interleukin-6 (IL-6) as predictive biomarkers for respiratory disease in foals from birth to weaning.
- To assess the association between CRP and IL-6 concentrations and foal health status post-weaning.
Main Methods:
- A prospective cohort study involving 200 foals from birth to weaning on a farm with endemic pneumonia.
- Weekly physical examinations and trans-thoracic ultrasonography were performed.
- Blood samples were collected periodically, and 90 foals (30 per health group) were analyzed for CRP and IL-6 concentrations using linear mixed models.
Main Results:
- Age-related variations in plasma CRP and IL-6 concentrations were observed.
- CRP concentrations increased, while IL-6 concentrations decreased through the weaning period.
- No significant impact of respiratory disease on CRP or IL-6 concentrations was detected at any age.
Conclusions:
- Neither CRP nor IL-6 concentrations proved to be effective predictors of subclinical or clinical bronchopneumonia in foals.
- Limitations include sample timing and small sample size.
- Further investigation is required to determine if frequent measurement of these markers aids in the diagnosis and prognosis of pneumonia in foals.
Background:
Early and specific diagnosis of bronchopneumonia in foals is important to prevent severe disease. In human medicine, C-reactive protein (CRP) and interleukin-6 (IL-6) are important diagnostic and prognostic biomarkers in neonatal pneumonia in other species. Evaluation of these markers in foals with naturally occurring respiratory diseases is lacking.
Objectives:
To determine if CRP and IL-6 were useful predictors of respiratory disease in foals from birth to weaning.
Study Design:
Prospective cohort study.
Methods:
Periodic blood samples from 200 initially healthy foals were collected from birth to weaning on a farm with endemic Rhodococcus equi and Streptococcus equi pneumonia. The foals were examined weekly by physical examination and trans-thoracic ultrasonography to determine the presence or absence of pulmonary consolidation and were divided into three groups after weaning: (1) foals that remained healthy; (2) foals that developed subclinical, mild, self-limiting pulmonary lesions; and (3) foals that developed severe pulmonary lesions and clinical pneumonia that required antimicrobial treatment. Thirty foals from each health group (N = 90 total foals) were randomly selected from the 200 initially enrolled for assessment of associations between CRP and IL-6 concentrations and health status. Data were analysed using linear mixed models, with p-values < 0.05 considered statistically significant.
Results:
Age-related changes were found in both plasma CRP and IL-6 concentrations. Circulating concentrations of CRP were increased through weaning, while plasma IL-6 concentrations decreased through weaning. Respiratory disease did not significantly impact concentrations of CRP or IL-6 at any age.
Main Limitations:
Timing of sample collection, small sample size.
Conclusions:
Neither IL-6 nor CRP concentrations were suitable predictors of subclinical or clinical bronchopneumonia in foals in this study. Further studies are needed to determine if more frequent measurement of these markers in foals at the time of pneumonia diagnosis provides helpful diagnostic or prognostic information.
