Mastectomy in ten mares: indications, surgical technique, complications, and long-term outcome.

Overview

• This study describes the reasons for performing mastectomy in mares, details the surgical procedures used, notes complications observed, and reviews long-term outcomes for 10 mares who underwent the surgery.

Study Purpose and Design

• The research aimed to identify the clinical indications leading to mastectomy in mares, explain the surgical techniques employed, and evaluate postoperative complications and long-term results.
• It involved a retrospective review of medical records spanning 27 years (1995–2022) from two university teaching hospitals.
• Researchers identified mares that underwent unilateral or bilateral mastectomy and collected detailed data about each case.
• Long-term follow-up was achieved through owner telephone interviews to assess recovery and survival.

Subjects and Conditions Treated

• The study included 10 mares affected by diseases of one or both mammary glands.
• Surgical removal involved one gland in 4 mares and both glands in 6 mares.
• Underlying conditions necessitating mastectomy included:
  • Chronic bacterial mastitis (4 mares)
  • Neoplasia (3 mares)
  • Lymphangiectasia (1 mare)
  • Pythiosis, a fungal-like infection (1 mare)
  • Lymphoid hamartoma, a benign growth (1 mare)

Surgical Technique and Intraoperative Details

• No mares experienced complications during the surgical procedures.
• Two different closure methods were used:
  • Primary wound closure was performed in 2 mares.
  • The remaining 8 wounds were left unsutured, allowing them to heal by secondary intention.

Postoperative Complications and Recovery

• Both mares with primary closure developed seromas (fluid-filled swellings), and one experienced wound dehiscence (partial opening of the surgical site).
• All surgical wounds, regardless of closure technique, healed completely within 3 months as reported by the owners.
• There were no intraoperative complications, indicating the surgery was generally safe to perform.

Long-Term Outcomes

• All mares returned to their intended use (e.g., riding, breeding) following recovery.
• Three mares were euthanized 2 to 4 years after surgery due to progression of the original disease, indicating that mastectomy was not curative in these cases.
• One mare died by drowning one year post-surgery, which was unrelated to the procedure.

Conclusions and Clinical Implications

• Mastectomy can serve as an effective treatment for mares with diverse mammary gland diseases that do not respond to medical management.
• The procedure appears safe with manageable complications and allows most affected mares to resume their normal activities.
• However, some underlying diseases may progress despite surgery, so prognosis varies with the condition treated.
• This study provides valuable information for veterinarians on when surgery is appropriate and what outcomes owners might expect.