Mastectomia in the horse- indication and surgical procedure

Abstract

Indications for mastectomia in horses are comparatively rare and accordingly there is not much literature about this procedure. Here we define and discuss the indication for mastectomia and the surgical procedure on the basis of seven cases (one mule, six horses) and describe the postoperative course. Four of the horses, three of them maiden mares, suffered from unilateral mastitis which was refractory to therapy (in some cases for months) and which was of a recurrent or destructive nature. Palpation of the affected mammary gland indicated chronic changes and permanent functional failure of the glandular tissue. No, or only limited aetiological diagnosis was possible. The clinical diagnosis was confirmed by postoperative pathohistological examinations, which revealed severe chronic inflammatory changes of the resected glandular tissue. The other three mares showed neoplastic changes (one malignant and one benign melanoma, one equine sarcoid), which necessitated amputation of one side of the udder. Unilateral mastectomia was performed with the mares under general anaesthesia in dorsal recumbency. During surgical preparation the contralateral side was carefully protected and accurate haemostasis was established. In all cases a drain was placed in the wound with an exit portal in the cranial aspect of the suture. In addition to perioperative treatment with NSAIDs, antibiotics and oral pro- and praebiotics, the main emphasis of the follow-up treatment was to provide sufficient drainage of the wound. In five mares the wound was flushed, and in two, a second portal for drainage was created in the standing mare. Wound infection occurred in one case. The mares were discharged between two and four weeks after surgery, when there was no longer need of wound treatment to avoid accumulation of exsudate. There were no medium to long term complications of the wound or of the contralateral side of the udder. At this time, more than two years after surgery, the mares suffering from benign melanoma or equine sarcoid have not shown any relapses. The mare operated on for malignant melanoma died shortly after surgery due to rupture of the spleen caused by metastases. We found that unilateral mastectomia is a successful measure for the treatment of destructive diseases of the udder resistant to medical treatment, and that this surgery preserves the function of one-half of the organ. In case of neoplastic diseases of the mamma the success of surgical treatment strongly depends on the status of the tumour. Although conservative treatment of mastitis is generally very successful, when it fails, resection of the irreversibly destroyed mammary gland is an appropriate treatment to terminate this painful condition in the mare.