Intestinal neoplasia in horses.
Authors: Taylor S D, Pusterla N, Vaughan B, Whitcomb M B, Wilson W D
Journal: Journal of veterinary internal medicine
Summary
Intestinal neoplasia in horses remains a challenging diagnosis with poorly understood epidemiology; this retrospective analysis of 34 histologically confirmed cases provides much-needed clinical characterisation. The study reviewed comprehensive clinical, clinicopathologic, and pathologic data from horses aged 2–30 years (mean 16.6 years), revealing that weight loss, colic, and anorexia were primary presenting complaints, whilst poor body condition, tachycardia, tachypnea, fever, and diarrhoea were consistent findings. Alimentary lymphoma predominated (followed by adenocarcinoma and smooth muscle tumours), with the small intestine most frequently affected; notably, Arabian horses demonstrated a 4.5-fold increased prevalence compared to other breeds, suggesting possible genetic susceptibility. Antemortem diagnosis proved difficult, achieved in only 38% of cases despite using rectal examination, blood work, abdominocentesis, ultrasonography, rectal biopsy, and exploratory laparotomy—highlighting the insidious nature of these conditions. The median survival from clinical onset was just 1.9 months with an overall discharge rate of only 15%, making early recognition through knowledge of breed predisposition and consistent clinical patterns essential for equine practitioners seeking to maximise diagnostic and prognostic accuracy.
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Practical Takeaways
- •Intestinal neoplasia should be considered in older horses (mean 16.6 years) presenting with weight loss, colic, anorexia, and fever, particularly in Arabian breeds
- •Diagnostic workup should include rectal examination, blood analysis, abdominocentesis, ultrasound, rectal biopsy, and exploratory laparotomy as antemortem diagnosis is challenging (38% success rate)
- •Prognosis is grave with median 1.9-month survival and 15% discharge rate; all horses in this series were eventually euthanized despite treatment attempts
Key Findings
- •Alimentary lymphoma was the most common intestinal neoplasia, followed by adenocarcinoma and smooth muscle tumors in 34 horses
- •Small intestine was the most frequently affected intestinal segment across all neoplasm types
- •Only 13 of 34 horses (38%) were diagnosed antemortem, with median survival of 1.9 months from clinical sign onset
- •Arabian breed horses were 4.5 times more likely to develop intestinal neoplasia than other breeds; mean age at presentation was 16.6 years