Surgical Management of Left-Hand Traumatic Injury in an Adult Female Captive Chimpanzee (Pan troglodytes): A Case Report

INTRODUCTION

Chimpanzees are particularly long-lived animals that are phylogenetically close to humans especially in social interactions, care, and management.^[1] However, reports by researchers of frequent and higher levels of aggressive behaviors with injuries among captive chimpanzees than those in the wild populations demand for investigation so as to improve care for the managed population of chimpanzees.^[2,3] The continued presence of human visitors with different affiliative behaviors and countenances are strong determinants of relationship value and compatibility. In the wild, chimpanzees are bedeviled by risks such as encounters with poachers and snares, accidents from crossing busy roads, predators such as Lions and Hyenas, etcetera. In general, Apes in managed care settings battle with a wide range of cardiovascular-related health problems such as periodontitis, hypertension, renal disease, and cerebral vascular diseases, which have been repeatedly confirmed as the most frequent cause of death following traumatic injuries.^[4,5]

Traumatic wounds have been identified as a distinct prevalent extrinsic cause of death for chimpanzees in the wild and captivity under managed care, in addition to complicating infectious factors, including those that are zoonotic in nature.^[1,6] The wound is also defined as a loss or breakage of cellular and anatomical or functional continuity of living tissue following physical, chemical, thermal, microbial, or immunological insult to the body.^[7] As observed by Gauthier^[2] and Ross et al.,^[1] affiliative behaviors, such as grooming, touching, close spatial proximity, and playing, reduce aggressive encounters such as anxiety, fight, and supplants in captive chimpanzees. Magden et al.^[8] reported oral lavender therapy in managing injured chimpanzees to decrease the percentage of wounds requiring medical intervention due to its stress relieving effect.

CASE REPORT

Management

The chimpanzee was lured into a squeeze cage, immobilized, and anesthetized [Figure 1a]. Analgesia and anesthesia were, respectively, achieved using Pentazocine (Pentalab^® - Laborate Pharmaceuticals Ltd., India) at 1 mg/kg intramuscularly and 50 mg/mL ketamine hydrochloride (Jawa ketamine^® - Swiss Parenterals Ltd., Gujarat, India) at 12 mg/kg + 2% Xylazine (Alfasan, Woerden-Holland) at 0.2 mg/kg intramuscularly. Three milliliters of whole blood was collected and dispensed into anticoagulant (Ethylenediamine tetraacetic acid) containing sample bottles which were used for hematology by an automated hematology analyzer (Mindray^® BC-3600, Shenzhen, China). Critical assessment of the wound [Figure 1b] was undertaken with the full extent of damage evident following proper cleansing and decontamination with Chlorhexidine gluconate (Purit^®) [Figure 1c]; thus, the adoption of amputation of the non-viable digits became the most viable option. The index and ring digits of the left-hand (with already lost proximal and middle phalanges) were dissected to expose the metacarpophalangeal joints from which the digits were disarticulated and the resulting defects reconstructed using size 1 vicryl^® suture apposing the surrounding tissues, while closing dead spaces and re-approximating the wound edges by simple continuous and intradermal suture patterns, respectively [Figure 1d and e]. The surgical site was sprayed with 10% oxytetracycline and the chimpanzee was administered with injection Tetatox^® (TT Vaccine) 0.5 mL IM ϰ¹/₇, injection 1% piroxicam at 0.3 mg/kg IM ϰ¹/₇ and 10% oxytetracycline 20 mg/kg IM ϰ¹/₇, and injection 1% ivermectin 0.6 mg/kg SC once weekly ϰ²/₅₂. Postoperatively, daily application of 10% oxytetracycline spray on the surgical site, doxycycline capsules 5 mg/kg ϰ ⁷/_7, and Dolo-meta-B^® (Vitamins B₁+B₄+B₁₂+Diclofenac Sodium) ϰ⁵/₇ orally were administered. The chimpanzee was immobilized fortnightly for re-assessment of healing and was finally relocated back to the Zoo’s sanctuary setting by day 42 post-operation [Figure 1f-h]. The peri-surgical vital parameters of rectal temperature, pulse and respiratory rates during the management periods are as shown in Figure 2.

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Figure 1:

Appraisal of digital amputation and wound management in an adult female chimpanzee. (a) Captured chimpanzee in a squeeze cage immediately following administration of anesthetics, (b) wound appearing desiccated before cleansing, (c) wound appearance after cleansing with soap, water and antiseptics, (d) disarticulated first phalanx of the left ring digit, (e) appearance of left-hand immediately following amputation of index and ring digits, (f) significantly healed wounds 2 weeks post-operation, (g) appearance 4 weeks post-operation, and (h) chimpanzee in the Zoo’s sanctuary setting on day 42 post-operation.

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Figure 2:

Peri-surgical vital parameters of rectal temperature, pulse and respiratory rates during digital amputation, and wound management in an adult female chimpanzee.

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DISCUSSION

On the surface, it may appear strange that despite the initial wound management by use of oxytetracycline spray in this case, disturbances of healing persisted. Although antiseptic and antibiotics are vital agents successful in wound management, adherence to the guidelines of the procedural ethics of wound examination and management are essential tools for a positive impact with the desired final clinical outcome.^[9] Wound management begins with a complete and detailed examination of the patient to assess, ascertain, and document the wound’s etiology, environment, and nature. These aid in the optimization of the patient’s medical condition, particularly diagnosis of life-threatening injuries, any underlying conditions such as exposed delicate tissues such as nerves, vascular supply, tendons, visceral organs, and bones. The management of such results in the restoration of blood flow to the wound area may be achieved by proper wound cleansing and debridement.^[7,9] In this case, a critical close assessment of the injured limb revealed devitalized soft tissue and proximal index and ring phalangeal bones, as well as infection, which all together served as a guide to the informed choice of management by amputation. The packed cell volume of 38% was within the normal reference established by Howell et al.^[10] Furthermore, the observed neutropenia and lymphocytosis in the leucogram is classical of chronic inflammation corroborating the reports by Witte and Barbul^[9] and strengthening the history of the wound being sustained for some weeks with no progressive healing following initial management. The instituted debridement coupled with irrigation of the wound aided the removal of dead, infected and hyperkeratotic tissues, as well as foreign materials on from the wound surface. This forms the basis of non-delayed as well as delayed wound healing as a vascularization of tissues prevents leukocytes, cytokines, growth factors, and other humoral factors that would have otherwise helped in infection control and hemostasis from gaining access to the wound site, thus the need to debride thereby accelerating wound healing as recorded in this case.^[7,9] Furthermore, the antibiogram susceptibility guided the choice of antibiotic administration in this case as this chimpanzee was in captivity as against their wild counterparts reported to engage in self-medication, suppressing or preventing the deleterious effects of parasitism and other frequent causes of illness through behavioral means.^[8]

CONCLUSION

In conclusion, prompt intervention, thorough clinical examination, informed decision on wound management options and protocol, gentle but proper tissue handling and consistent wound care coupled with rational drugs use are essentials to achieve a timely and uneventful wound healing especially in captive chimpanzees.