Pheochromocytoma in two horses.

This research article documents the diagnosis and autopsy results of two horses, a 12-year-old Standard-bred mare and a 21-year-old Quarter Horse gelding, that showed signs of pheochromocytoma – a rare type of tumour.

Case Presentation

• The study presents two cases of horses: a 12-year-old Standardbred mare and a 21-year-old Quarter Horse gelding who were treated for symptoms of abdominal pain and excessive sweating. The mare also exhibited muscle twitching, azotemia (abnormal levels of nitrogen-containing compounds in the blood), and ataxia (lack of voluntary coordination of muscle movements).
• The mare was euthanized once the signs of pain became impervious to pain relief medication. On the other hand, the gelding died due to ventricular tachycardia (a heart condition that causes a fast heartbeat) that developed during general anesthesia for an investigative surgery (exploratory celiotomy).

Autopsy Findings

• Upon postmortem examinations, adrenal pheochromocytomas or adrenal gland tumours (bilateral in the mare), linked to retroperitoneal (the anatomical space in the abdominal cavity behind the peritoneum) and intra-abdominal hemorrhage (bleeding), were discovered.

Research Conclusion

• The article suggests that pheochromocytoma should be a potential diagnostic consideration in older horses exhibiting signs of abdominal pain and sweating. The suspicion should be further strengthened in older horses presenting symptoms such as muscle twitching, ataxia, azotemia, and intraperitoneal hemorrhage.
• In addition, the findings from the mare’s autopsy led the researchers to suggest that a recognition of swelling in the retroperitoneal area in the dorsal aspect of the abdomen (recognized via rectum palpation), should serve as a sign to diagnosticians for a potential ruptured pheochromocytoma.

Implications of the Study

• This study adds to the limited knowledge about pheochromocytoma in horses, shedding light on its symptoms, medical management, and pathological findings. With further research, these findings could aid in early detection, diagnosis, and appropriate treatment strategies.