Clinical and pathologic findings of splenic tumours in four horses: a case series.

Objective Summary

• This study reviews the clinical and pathological characteristics of splenic tumors in four horses, highlighting their presentation, diagnosis, and outcomes.

Background

• Splenic tumors in horses are rare, with limited literature mainly comprising isolated case reports and one small case series on hepato-splenic lymphoma.
• This study adds to existing knowledge by analyzing four cases seen at a university referral hospital over three years (2022-2025).

Study Objective and Design

• The objective was to analyze clinical presentation, diagnostic findings, and outcomes for horses with splenic tumors.
• This is a retrospective case series of four horses diagnosed with splenic neoplasia.
• Two tumor types were represented: primary splenic lymphoma and metastatic melanoma.

Clinical Presentation

• Three of the four horses (75%) showed chronic, non-specific signs such as weight loss, colic (abdominal pain), and ventral edema (swelling on the underside).
• One horse (25%) presented acutely, showing signs of hypovolemia (low blood volume) caused by rupture of the spleen.
• This suggests that splenic tumors typically cause subtle, long-term symptoms but can occasionally lead to emergency situations if the spleen ruptures.

Diagnostic Approach

• All horses underwent transabdominal ultrasonographic examination, which reliably identified masses on the spleen.
• Definitive diagnosis was established via post-mortem histopathological examination of the splenic tissue.
• Ultrasound was effective in detecting lesions but could not replace histopathology for a conclusive diagnosis.

Types of Tumors

• Primary splenic lymphoma was the most common primary tumor observed.
• Metastatic melanoma was the predominant metastatic splenic tumor identified.

Clinical Significance and Implications

• Splenic tumors in horses often present with vague signs like chronic weight loss and abdominal discomfort, similar to what is seen in humans with splenic masses.
• In some cases, acute complications such as splenic rupture can lead to sudden and severe clinical presentations.
• Specialists and clinicians should include splenic neoplasia in their differential diagnosis when horses show chronic nonspecific symptoms affecting weight and abdominal health.
• The true extent of tumor spread in the spleen and other organs (visceral metastases) is frequently underestimated based on tests done before death.

Conclusions

• Although rare, splenic tumors can be an important consideration in equine medicine, especially for unexplained, persistent illness involving weight loss and abdominal signs.
• Ultrasound is a useful diagnostic tool to detect splenic masses but must be complemented by histopathology for a definitive diagnosis.
• Awareness of these tumors can improve clinical suspicion and potentially lead to earlier diagnosis and intervention.