Abstract
Modern elephant management programs often include the use of protected contact. This allows improved safety for the elephant staff but may limit access to medical conditions occurring in elephants.
A 27-yr-old, female African elephant (Loxodonta africana) weighing an estimated 3,700 kg was anesthetized for evaluation of a chronic, progressive, fistulous tract of the left ventral mandible. The mandible was routinely cultured, flushed with diluted peroxide, chlorhexidine, betadine solution, or alternating antibiotics, based on microbial sensitivities. To properly assess the left mandible, the elephant had to be placed in right lateral recumbency, which was accomplished with the use of a commercially available rotational elephant restraint device (ERD). Because of the protected contact management program, right lateral recumbency could not be guaranteed at the time of immobilization. Malpositioning, tusk fracture and/or related injury could occur upon recumbency without the additional control afforded by the ERD.
The ERD is a hydraulically operated unit that comfortably restrains an elephant, minimizing safety risks to the animal and staff. The ERD consists of one solid wall, three side panels, and hinged floor. The ends of the restraint are closed with moveable shift doors. The three side panels can be moved independently depending upon the size of the animal and are further subdivided with moveable “subpanels” to allow direct access to various areas of the animal. In addition, support straps help gently stabilize limbs when performing medical procedures. The unit is positioned within the elephant holding facility at the Kansas City Zoo. The unit was installed in 1994 during renovation of the elephant exhibit, whereupon the elephant management program was changed from free-contact to protected contact. The ERD is utilized for reproductive assessments, semen collection, transabdominal ultrasound, evaluation of integumentary wounds, ophthalmic and aural examination, and administration of injectable medications. However, no elephant had been anesthetized and rotated in the restraint. The affected animal could not be guaranteed to re-enter the ERD once rotated, but would enter and station in the ERD on a daily basis. Because of this, a conspecific was conditioned to allow rotation without the use of sedatives or tranquilizers, to prepare for the actual immobilization. Adjustments in strap placement, cushioning, critical evaluation of mechanical stability, and placement of hydraulic panels allowed staff to prepare for the actual immobilization, minimizing complications.
The elephant was conditioned to enter and station in the ERD. After strapping the distal limbs, thorax and caudal abdomen for support, the elephant was immobilized with a combination of 3,000 IU of hyaluronidase (O’Brien Pharmacy, Kansas City, MO, USA), 10 mg acepromazine maleate, and 7 mg etorphine hydrochloride (Wildlife Pharmaceuticals Inc., Fort Collins, CO, USA) via pole syringe. Close monitoring of induction was performed and when stage III anesthetic plane was achieved, the elephant was rotated into right lateral recumbency, elevating the elephant 6 feet above the floor. No voluntary movement of the animal was noted while the restraint was in motion. Direct arterial blood pressure, indirect oscillometric blood pressure, blood gases, respiratory rate, excursion characteristics, cardiac rate and rhythm, and pulse oximetry were routinely monitored during the procedure. Anesthesia was maintained with intermittent boluses of etorphine hydrochloride. Intravenous physiologic fluids (lactated Ringer’s solution) were maintained via an IV aural catheter, and insufflation with oxygen was provided on a continual basis.
Oral examination and palpation demonstrated an incomplete transverse fissure of the left mandibular molar, intact gingival, and proper dental occlusion with the upper arcade. Digital radiographs of the left mandible were performed based on exposures obtained with a set of skeletonized jaws. Advantages of this diagnostic modality are the immediate imaging results, portability, and digital imaging and storage, and it does not require a developer or fixative. Adjustments in radiographic angle and technique were made to obtain the best diagnostic image. Radiographic imaging demonstrated a sequestrum consisting of a fractured enamel plate2 of the mandibular molar with a fistulous tract that coursed ventrally to communicate through the skin.
The elephant was elevated 6 feet above the ground, which presented unique challenges. Because of the relatively small operating space, intubation was not possible, but insufflation was readily achieved and successful based on pulse oximetry trends. A commercial lift was utilized to elevate two large-animal circle anesthetic units to the level of the elephant’s head. During immobilization, the legs were cushioned and restraint straps removed to lessen the potential for occlusive damage to the tissues. The ERD allows an elephant to be positioned in either right or left lateral recumbency.
Upon completion of diagnostic procedures, the narcotic agent was reversed with 1,400 mg naltrexone hydrochloride (ZooPharm, Laramie, WY, USA) administered 25% intravenously and 75% subcutaneously. The elephant awoke within 90 sec and was rotated to a standing position within the restraint. Thereafter, the elephant was confined in the restraint for approximately 45 min, until no untoward effects were likely to occur. The elephant was released from the restraint and resumed normal eating and drinking within 8 h, and voluntarily entered the restraint within 2 wk following the procedure.
The elephant was stable throughout the procedure; however, a predetermined objective for mean arterial blood pressures (<200 MAP) was not achieved. Hyaluronidase was utilized to promote rapid absorption of the narcotic and neuroleptic agents.3 Acetylpromazine was used to maintain peripheral perfusion by reducing the hypertensive effects of etorphine,1 which has been documented in previous immobilizations of African elephants3-5. Etorphine hydrochloride, a powerful narcotic agent, has been successfully used as an immobilizing agent in both wild and captive African elephants.3-5
Use of an ERD allowed full control of the immobilization, increasing safety for personnel, preventing injury to the elephant, and positioning the left mandible on the dorsal plane. Disadvantages are the elevated height of the elephant, relatively small operating space, and disrupted line of sight communication.
A second procedure will be performed in the near future to address the fracture and subsequent sequestrum diagnosed during the first immobilization. The elephant is currently being conditioned to allow restraint in a holding stall that will allow greater access to the oral cavity and surgical manipulation of the affected mandible.
Acknowledgments
We thank the staff of the Kansas City Zoological Park for their care, concern, and expertise in helping make this procedure a success.
Literature Cited
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