In equine grass sickness, serum amyloid A and fibrinogen are elevated, and can aid differential diagnosis from non-inflammatory causes of colic.
Authors: Copas V E N, Durham A E, Stratford C H, McGorum B C, Waggett B, Pirie R S
Journal: The Veterinary record
Summary
# Editorial Summary Equine grass sickness (EGS) presents a significant diagnostic challenge in clinical practice, with presumptive diagnosis relying on clinical signs and subjective tests until definitive histopathological confirmation through intestinal biopsy. Copas and colleagues quantified three serum inflammatory markers—serum amyloid A (SAA), fibrinogen, and activin A—across acute, subacute and chronic EGS cases, comparing them with co-grazing horses, cases of non-inflammatory colic, inflammatory colic, and healthy controls. Both SAA and fibrinogen showed marked elevations in EGS cases relative to healthy horses and those with non-inflammatory colic, though concentrations were similar to inflammatory colic cases, whilst activin A was significantly elevated in both EGS-affected and co-grazing horses, suggesting possible subclinical exposure in asymptomatic animals. These findings indicate that measuring acute phase proteins may help differentiate EGS from mechanical causes of colic such as obstructions, though practitioners should exercise caution when distinguishing EGS from other inflammatory abdominal conditions like peritonitis or enteritis. For field and referral practitioners, incorporating SAA and fibrinogen testing into the diagnostic workup of colic cases may improve confidence in ruling in or ruling out EGS, potentially streamlining management decisions where biopsy is not immediately accessible.
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Practical Takeaways
- •SAA and fibrinogen testing can help rule out non-inflammatory colics (e.g., obstruction) in suspected EGS cases, but cannot definitively diagnose EGS or differentiate it from other inflammatory abdominal conditions
- •Elevated acute phase proteins in a colic case should prompt investigation for inflammatory causes including EGS, peritonitis, and enteritis rather than assuming simple obstruction
- •Activin A elevation in clinically normal co-grazing horses warrants monitoring, as it may indicate subclinical EGS exposure and risk of disease development
Key Findings
- •Serum amyloid A (SAA) and plasma fibrinogen were markedly elevated in EGS cases compared with healthy horses, co-grazers, and non-inflammatory colic cases
- •SAA and fibrinogen concentrations in EGS cases were not significantly different from inflammatory colic cases, limiting diagnostic specificity
- •Activin A was significantly elevated in both EGS cases and co-grazing horses, suggesting widespread exposure to the aetiological agent and possible subclinical disease
- •Marked increases in acute phase proteins may help differentiate EGS from non-inflammatory causes of abdominal pain such as intestinal obstruction