Multimodal Anesthesia in Gallus gallus domesticus for Therapeutic Ovariohysterectomy

Anestesia em aves

Abstract

Background: Egg retention and yolks in the oviduct of birds is a common pathology that is treated by surgical removal of the oviduct itself and its appendages. For the bird's comfort and to reduce the painful stimulus, it is essential to use analgesia correctly, as well as systemic anti-inflammatories, in order to reach different phases of the nociceptive pathway. Local anesthetic blocks can also be used, which can reduce the need for systemic drugs and inhaled anesthetics. The aim of this report is to describe a multimodal analgesic approach with spinal anesthesia in a domestic hen who underwent ovariohysterectomy due to egg retention.

Case: A domestic hen (Gallus gallus domesticus) was referred to the University Veterinary Hospital (HVU) of the Federal University of Santa Maria (UFSM) with egg retention in the oviduct and the treatment of choice was therapeutic ovarian-salpingohysterectomy (OSH). Pre-anesthetic medication was combined with opioid, dissociative and benzodiazepine. The hen was induced into general anesthesia with isoflurane diluted in 100% oxygen via face mask, followed by intubation and venous access puncture in the left medial tibiotarsal vein. After which it was placed in the sternal decubitus position for anesthetic block via local spinal anesthesia. Anesthesia was maintained using a Baraka non-rebreathing gas system, with spontaneous and manual assisted ventilation. During the surgical period, heart rate, respiratory rate, peripheral oxygen saturation, temperature and carbon dioxide fraction at the end of expiration were monitored. After the end of the procedure, within 1 h, the patient began to respond to external stimuli and 1 h and 30 min after the end of the procedure, she was released for anesthetic discharge and sent to hospital, demonstrating the immediate anesthetic success of the procedure.

Discussion: Surgical removal of the oviduct and its appendages, as the ovary, was performed as indicated in the literature. The anesthetic team used drugs from the opioid, benzodiazepine and disociative classes as pre-anesthetic medication, which proved to be beneficial, since previous studies show that the combination brings analgesic comfort, muscle relaxation and sedation, reducing the need for inhaled anesthetics at the time of induction. Induction was carried out using an isoflurane mask diluted in 100% oxygen and lasted just 2 min, allowing the bird to be intubated and monitored using the multiparameter monitor. The anesthesiologist in charge performed a spinal neuroaxis block, an uncommon practice in birds, which contributes to blocking different nociceptive pathways in the trans-operative period. During the trans-surgical period, bradycardia was noted through monitoring, which was soon corrected through the intravenous application of atropine. There was a decrease in the bird's spontaneous ventilation in the final 35 min of the procedure, so the bird was ventilated manually until it returned to spontaneous ventilation, which may have been due to the inhaled anesthetic and the dorsal decubitus position, plus the weight of the surgical drapes. The bird was then sent to anesthetic recovery, where it was warmed up using a neonatal incubator and discharged from anesthesia after 1 h and 30 min. This result proved satisfactory for the team, who quickly directed the patient, which was the expectation of the anesthetic and surgical teams.

Keywords: egg retention, analgesia, domestic hen, chicken, bird, surgery. 

Título: Anestesia multimodal em Gallus gallus domesticus para ovariohisterectomia terapêutica.

Descritores: retenção de ovos, galinha doméstica, ave, multimodal, anestesia.