Serum amyloid A alone or in combination with white blood cell count and fibrinogen is associated with inflammatory disease status in horses undergoing elective anesthesia.

Overview

• This study investigated the usefulness of blood tests measuring inflammatory markers—specifically serum amyloid A (SAA), white blood cell count (WBCC), and fibrinogen—to detect disease in horses undergoing elective general anesthesia.
• The research found that SAA, either alone or combined with WBCC and/or fibrinogen, was most strongly associated with identifying inflammatory disease status before surgery.

Background and Purpose

• Elective anesthesia in horses requires careful preoperative evaluation to ensure patient safety and optimize outcomes.
• Common blood markers of systemic inflammation include:
• White Blood Cell Count (WBCC): Often elevated during infection or inflammation.
• Fibrinogen: A plasma protein that increases in response to inflammation.
• Serum Amyloid A (SAA): An acute phase protein rising rapidly during systemic inflammation.
• The goal was to determine which of these blood markers, alone or in combination, best indicated disease presence in horses before undergoing anesthesia.

Methods

• This was a retrospective study analyzing 1,002 surgical cases from February 2021 to June 2023.
• Inclusion criteria:
• Horses undergoing elective orthopedic or soft tissue surgery.
• Systemically stable (no obvious severe systemic illness at time of surgery).
• Preoperative blood testing available for WBCC, fibrinogen, and SAA.
• Final disease classification for each horse was assigned based on diagnostic outcomes and any identified comorbidities.
• Statistical analysis:
• Univariable logistic regression to individually assess each marker’s association with disease status.
• Multivariable logistic regression to evaluate combinations of markers and determine best diagnostic models.

Results

• 997 horses met the inclusion criteria and were included in final analysis.
• Individually, all three markers (WBCC, fibrinogen, and SAA) showed significant association with the presence of disease.
• SAA was the strongest single marker for detecting inflammatory disease.
• When combined with WBCC and/or fibrinogen, SAA significantly improved the predictive power of the diagnostic models.
• This was measured using the area under the receiver operating characteristic curve (AUROC), with models including SAA yielding the highest accuracy.

Discussion and Clinical Implications

• Measuring SAA before anesthesia provides a valuable and sensitive means to detect underlying inflammatory disease in horses, even when systemic signs seem stable.
• SAA testing can be easily and rapidly performed stall-side using handheld devices, making it practical for field use or clinics with limited laboratory resources.
• Combining SAA measurement with standard inflammatory markers like WBCC and fibrinogen offers the best diagnostic confidence.
• Equine practitioners should consider including SAA testing as part of preanesthetic blood work to better assess patient health status and optimize anesthesia safety.

Conclusion

• This study supports the routine use of serum amyloid A testing, alone or with white blood cell count and fibrinogen, as an effective tool for identifying inflammatory disease in horses undergoing elective surgery.
• The approach is both practical and cost-effective, enhancing perioperative patient assessment in hospital and field environments.