An evaluation of diagnostic data in comparison to the results of liver biopsies in mature horses.
Authors: Durham A E, Smith K C, Newton J R
Journal: Equine veterinary journal
Summary
# Diagnostic Testing for Equine Hepatopathy: Limitations of Non-invasive Procedures Durham and colleagues compared clinical examination, ultrasonography and serum biochemistry against liver biopsy histopathology in 82 mature horses with suspected hepatic disease, establishing biopsy as the definitive diagnostic gold standard and quantifying the reliability of non-invasive investigations in a population where 74% ultimately had significant liver pathology confirmed. Whilst certain individual markers—notably gamma-glutamyltransferase (GGT), globulins, alkaline phosphatase, total bile acids and total bilirubin—demonstrated good positive predictive values when markedly elevated, no single test or combination thereof reliably excluded liver disease, meaning negative results cannot confidently rule out significant hepatopathy. The presence of hepatic encephalopathy, clinical signs and ultrasonographic abnormalities were relatively good indicators of disease when present, yet their absence did not exclude pathology. This fundamental asymmetry in diagnostic utility has important implications for practice: whilst marked elevations in GGT or hyperglobulinaemia support a diagnosis of liver disease, normal or mildly abnormal results do not justify dismissing hepatopathy as a differential diagnosis without further investigation. Clinicians managing suspected equine liver disease should recognise the significant limitations of non-invasive testing and maintain a lower threshold for recommending biopsy, particularly where clinical suspicion remains high despite unremarkable biochemical or ultrasonographic findings.
Read the full abstract on PubMed
Practical Takeaways
- •Elevated gamma-glutamyltransferase and globulins, plus clinical signs of hepatic encephalopathy, are your best noninvasive indicators of liver disease, but a normal result does not rule out disease.
- •Do not rely on serum biochemistry alone to confirm or exclude significant liver disease in suspected hepatopathy cases—consider liver biopsy for definitive diagnosis when clinical suspicion is high.
- •Clinical abnormalities and ultrasonographic findings, when present, are reasonably good indicators of liver disease, but absence of these signs does not exclude disease.
Key Findings
- •Of 82 suspected hepatopathy cases, 61 had biopsy-confirmed liver disease and 21 did not; only gamma-glutamyltransferase, globulins, and alkaline phosphatase were significantly different between groups.
- •No single or combined noninvasive test achieved high sensitivity, specificity, positive predictive value, and negative predictive value simultaneously.
- •Positive results for hepatic encephalopathy, elevated gamma-glutamyltransferase, hyperglobulinaemia, and hypoalbuminaemia reliably predicted liver disease presence, but negative test results poorly predicted disease absence.
- •Liver biopsy histopathology remains the gold standard for definitive diagnosis; reliance on noninvasive tests alone may lead to frequent diagnostic errors.