Abstract

Following a confrontation in the chimpanzee house in September 1999, the oldest male chimpanzee (Pan troglodytes) was separated due to significant hemorrhage from the feet and inability to use either foot normally. Once separated, this animal became quiet and trembled uncontrollably.

Immobilization was elected using 500 mg Telazol (Fort Dodge Laboratories, Inc., Fort Dodge, IA 50501 USA; 250 mg tiletamine and 250 mg zolazepam) by remote dart intramuscular injection. Examination under anesthesia within 2 hr of the fight showed that this animal sustained multiple full-thickness flesh wounds, lacerated tendons, joint luxations, and metatarsal and phalangeal fractures to both feet. Halluxes were not affected.

Initial therapy included intravenous lactated ringer's solution (Abbott Laboratories, North Chicago, IL 60064 USA) and piperacillin sodium (Lederle Piperacillin Inc, Carolina, Puerto Rico 00987) added to the fluids at 4 g/L of fluid. The wounds were cleansed to removed hay and fecal material and gently debrided. Anterioposterior and lateral radiographs were taken to evaluate the extent of the injuries. The most severe fracture involved three fragments of metatarsal four (MT 4) of the right foot with the central fragment incorporating approximately one-third of this bone. The viability of this fragment was uncertain at the time of initial evaluation. The extensor tendon overlying this fracture site was lacerated and exposed.

Conservative wound care was chosen pending consultation with a veterinary surgeon and human orthopedic surgeon. One gram of piperacillin was instilled onto gel foam and placed into the wounds. Wet-to-dry bandages were placed on both feet using a 1:40 dilution of chlorhexidine diacetate (Fort Dodge Laboratories, Inc., Fort Dodge, IA 50501 USA). Quick setting cast material (Scotchcast-plus casting tape, Orthopedic Products, 3M Health Care, St. Paul, MN 55144 USA) was applied over the bandages to stabilize the fractures and to impede removal of bandages by the animal. Six hundred milligrams of methocarbamol (Fort Dodge Animal Health, Fort Dodge, IA 50501 USA) was given i.m. divided into two sites to facilitate sedation and muscle relaxation following initial evaluation and treatment. This resulted in a very sedate, inactive chimpanzee for the initial 24 hr. The animal would interact with keepers after awaking from general anesthesia.

Bandaging was initially scheduled once daily for two treatments and then every 2-3 days for 2 wk. A human orthopedic surgeon was consulted to evaluate the radiographs and to assist with wound and fracture management. At this time, the surgeon felt that the large fragment from MT 4 necessitated removal and that the wounds would heal with conservative care, allowing the animal to regain some use of the foot. The fourth treatment (1 wk after initial injury) involved a closer evaluation by the orthopedic surgeon and included removal of a large piece of nonviable MT 4 bone and damaged tendon, as well as more aggressive soft tissue debridement. Medical management continued with 500 mg piperacillin i.v. and 500 mg ceftazidime (Glaxo Wellcome, Inc., Research Triangle Park, NC 27709 USA) i.m. and 500 mg intralesional piperacillin for the first week during immobilizations. Oral therapy between immobilizations included 1000 mg cephalexin monohydrate (TEVA Pharmaceuticals USA, Sellersville, PA 18960 USA) b.i.d. for 2 wk and 360 mg acetaminophen (Infant's Tylenol syrup, McNeil Consumer Products Company, Camp Hill Road, Fort Washington, PA 19034 USA) daily as needed for pain.

While in casts, this chimpanzee would maneuver by scooting along its ischial region while propelling with its arms. After 3-4 weeks this animal began to develop ischial callouses. Although the keepers encouraged the chimpanzee to stand as much as possible with the assistance of the metal mesh doors, the majority of this animal's time was spent sitting or lying on the floor.

After the initial 3 wk and a follow-up consultation with the orthopedic surgeon, recheck examinations and bandage changes were scheduled every 2-3 wk until the casts and bandages were no longer needed. Oral antibiotic therapy was discontinued after 3 wk to prevent the development of antibiotic resistant infections. After 9 wk of treatment the casts were removed, one at a time, at a 3-wk interval. There was noticeable muscle atrophy to both lower limbs as the casts were removed. The chimpanzee began using each foot within 24 hr after cast removal and quickly seemed to regain strength and muscle tone. By 12 wk post-injury both casts were off and this animal was fully ambulatory. Full function returned to all toes on the left foot and to two of five toes on the right foot.

Three months after the initial injury this male was returned to the chimpanzee troupe. Currently, this animal is ambulating well, climbing, displaying, and remains very active within in the group.

The wounds this animal sustained were significant enough to warrant intervention. Surgical repair of several fractures was initially discussed and intramedullary pinning was considered for two of the metatarsal fractures of the right foot. The conservative approach was chosen due to questionable viability of the central fragment of MT 4. It was felt that the wounds and fractures would heal adequately with minimal manipulation.

At the onset of therapy and casting, heavy sedation and muscle relaxation successfully kept this animal calm and relaxed, thus avoiding disruption of the casts and preventing rhabdomyolysis from pain-related tension and trembling. After discontinuation of muscle relaxants the chimpanzee continued to leave the casts and bandages alone. Only once was a cast removed by this animal during a darting episode. This cast was most likely already loose and initially not placed high enough above the ankle.

The modified wet-to-dry bandaging technique achieved satisfactory debridement and wound protection to allow granulation of the wounds. The casting material prevented bandage removal by the patient, stabilized the fractures and dislocations, and provided a limited degree of waterproofing. Repeat immobilizations with tiletamine/zolazepam were handled well by this individual. The dose ranged from 300 to 500 mg depending upon the degree of sedation already present from concurrent administration of a muscle relaxant. Several immobilizations were preceded by medetomidine (Domitor, Pfizer Animal Health, Exton, PA 19341 USA) administered at 3 mg orally 30 min prior to darting. This preanesthetic tranquilization had variable results. Fight-related trauma is perhaps the most common cause of injury in chimpanzees housed together. Injury is seldom serious enough to warrant immediate intervention in the chimpanzee group housed at Busch Gardens, Tampa, Florida. This case illustrates the successful management of serious fight-induced injuries in a large primate and the efficacy of quick-setting casting materials and modified wet-to-dry bandaging technique. The described treatment, together with extensive husbandry modifications and extra staff efforts (separation of animal from the group, extra hand feeding sessions, daily medications), resulted in return to acceptable function of this animal's feet and ultimately its return to function in the social order of the chimpanzee group.

Acknowledgments

The authors greatly appreciate the long hours and hard work put in by the dedicated managers and keepers of the great apes at Busch Gardens, Tampa, Florida. Special thanks to Preston Stubbs, DVM and co-author Thomas Greene, MD for the generous donation of their time in consultation on this case.