Treatment of congenital atypical haemangiosarcoma in a foal

Haemangiosarcoma is a rare vascular tumour in horses, usually originating from blood vessel endothelial cells. We present the case of an 8-day-old foal, referred for an atypical large subcutaneous mass on the left side since birth. Ultrasonographically, it showed multiple cavities with hypoechoic content, marked vascularisation and fluid movement between cavities. As the nature of the mass suggested that surgery could result in profuse bleeding, we decided to perform an initial arteriography to identify the pattern and calibre of the main vessels and embolisation of this vascular supply, which allowed surgical removal with less bleeding than expected. This approach, with pre-surgical transarterial embolisation of the tumour, is not commonly used in equine surgery. Histology established a diagnosis of cutaneous haemangiosarcoma. During 1-year post-surgery, clinical and ultrasound examinations were carried out without any signs of recurrence or metastasis. One year later, the foal was euthanised due to a limb fracture. No macroscopic signs of metastasis were observed at necropsy. Histology showed no signs of recurrence. Cutaneous haemangiosarcomas, though rare, should be included in the differential of masses and growths with compatible ultrasound or cytological findings. Transcatheter arterial embolisation of highly vascularised neoplasms can reduce bleeding and facilitate subsequent surgical resection.