Surgical contraception of free-ranging female capybaras: Description and comparison of open and minimally invasive techniques

Sterilization of free-ranging female capybaras (Hydrochoerus hydrochaeris): a comparison between two surgical techniques

This study evaluated two surgical sterilization techniques in free-ranging female capybaras (n = 21). The first group underwent uterine horn ligature (HL; n = 11), while the second was subjected to partial salpingectomy (S; n = 10). We assessed total operative time, incision length, the ease of identifying reproductive structures, the adequacy of exposure for surgical performance through flank or midline approaches, and the extent of abdominal viscera manipulation for each method. The HL method emerged as faster, with an average operative time difference of 16 minutes. In the S group, a flank mini-laparotomy over the ovarian topography facilitated easy exposure of the ipsilateral ovary and uterine tube, enabling ligature and partial resection of the uterine tube but not the uterine horn exposure. However, accessing the contralateral uterine tube without a bilateral incision was impractical, thus prolonging the total operative time due to the need for patient repositioning and new antisepsis procedures. Conversely, a post-umbilical approach for the HL method necessitated only one mini-laparotomy incision, offering ample uterine exposure for hysterotomy in pregnant females. Both methods involved minimal abdominal viscera manipulation and resulted in no fatalities or postoperative complications. Although direct comparison is limited by the distinct sterilization techniques and surgical approaches, this study underscores the challenges and surgical access of each method. Our findings endorse the HL technique as an effective contraception method for female capybaras to prevent the birth of seronegative offspring that could amplify Rickettsia sp., the causative agent of Brazilian spotted fever.

Laparoscopic Salpingectomy and Vasectomy to Inhibit Fertility in Free-Ranging Nutrias (Myocastor coypus)

The nutria (Myocastor coypus), an invasive alien species, is widely spread in Europe. Pursuant to regulation (EU) no. 1143/2014, the nutria is subject to management programs to reduce its spread. Surgical fertility control is considered an acceptable method, particularly in urban circumstances, avoiding euthanasia. To maintain the hormonal patterns and the social and behavioral dynamics, surgical infertilization preserving the gonads (i.e., salpingectomy and vasectomy) is recommended. Mini-invasive surgery is an eligible choice when dealing with wildlife, allowing reduced captivation time. For these reasons, 77 free-ranging nutrias, captured in urban nuclei in Italy, underwent infertilization under general anesthesia; laparoscopic salpingectomy and vasectomy were performed on 32 animals and traditional surgery on the remainder, leaving the gonads in place. A three-port technique was used, with two paramedian trocars (5 mm) for the instruments and a median one for the telescope. Ablation was obtained through Onemytis® plasma device, allowing a rapid surgical time with no need to place visceral sutures; the skin was surgically closed. After recovery, the animals were released, and no overt complications were noted. No modification of the behavioral patterns was noted, and the population decreased during the following months.

Surgical sterilization of free-ranging capybaras (Hydrochoerus hydrochaeris): “Passos Nunes” uterine horn ligature

Capybaras are the primary hosts of Amblyomma sculptum tick, vectors of Rickettsia rickettsia bacteria, and the zoonotic agent of Brazilian Spotted Fever (BSF). In this context, contraceptive methods have been suggested for population control in order to reduce the number of free-ranging capybaras cohabiting with humans in urban and rural areas and acting as disease amplifiers. To maintain the group's expected behavior and social hierarchy, sterilization techniques that preserve the gonads are recommended. On 126 female capybaras in the Brazilian state of São Paulo, a new surgical technique named “Passos Nunes” uterine horn ligature was performed after adequate general anesthesia. It achieved effective surgical sterilization, with an incision length of about 3 cm in the periumbilical linea alba, cranial to the pubis. After entering the abdominal cavity, the urinary bladder is pulled laterally to access the uterine horns and the cervix. The uterine horn is folded up, forming a strap; the distal portion of the strap is ligated and its distal end sectioned. The exact process is performed on the opposite horn. After the surgical procedure, the musculature is sutured in a sultan pattern and the subcutaneous tissue with a horizontal mattress pattern. The skin is sutured in a separate simple format, using nylon 2.0 for all steps. The wide exposure of the uterine horns facilitates the confirmation of pregnancy, allowing the surgeon to choose between salpingo hysterectomy or ligature of the uterine horns. The present study presents a new technique of surgical sterilization that can be used in female free-ranging mammals in which maintenance of the gonads is recommended, and births of offspring should not occur.