Abstract

A 30-yr-old, captive-born, male Sumatran orangutan (Pongo pygmaeus abelii) with no prior medical history presented on the afternoon of day 1 with a plum-sized dependent swelling of the throat sac region. Medical history was unremarkable. The animal was quieter than usual and appeared sweaty and feverish. A preliminary diagnosis of early/mild throat sacculitis was made based on species predilection and presenting symptoms. Ceftazidime (2 g IM) was administered and a medical work-up planned for the following day. In the early morning of day 2, the animal was found recumbent, unresponsive to voice or touch, but breathing steadily and blinking his eyes. Septic shock was suspected. The throat sac swelling was the size of a small basketball and was dense rather than fluid filled. The epidermis had sloughed, leaving a white, devitalized, glistening surface.

Physical examination, bacterial culture and biopsy of the affected region confirmed necrotizing fasciitis caused by beta-hemolytic Streptococcus, Group A. Surgical intervention was performed the same day and included aggressive debridement/resection of all portions of the necrotic skin and underlying subcutaneous tissue. The throat sac mucosa was not involved with the necrotizing disease process and was left intact throughout the surgery. The resulting suture line extended approximately 40 cm in a crescent shape from below one ear, across the anterior thorax, to just below the opposite ear. It was not possible to excise all affected tissues and still achieve complete primary closure. Since management of a postoperative wound was not possible in this patient, primary closure necessitated leaving small portions of devitalized tissue along portions of the suture line.

Postoperative medical care and husbandry focused on aggressive antibiotic therapy and deterrents to dehiscence of the suture line by the orangutan. Antibiotic therapy included parenteral clindamycin (8 mg/kg IM, BID), amikacin (7 mg/kg IM, BID) and enteral amoxicillin (7 mg/kg PO, TID). The animal was a highly motivated suture picker. Techniques employed to deter this behavior included 24 h observation with positive and negative reinforcement, the sleep aid zolpidem tartrate (Ambien, Sanofi-Synthelabo, Inc., New York, NY, 10 mg PO in the evening), acepromazine (0.22 mg/kg PO, TID), food stuffs braided into the animal’s hair and other enriching/distracting items. Diazepam (0.25 mg/kg PO) was tried but had little effect on the suture picking behavior.

A single follow-up procedure to further debride and close a partial dehiscence of the surgical site was performed on day 4. The animal recovered uneventfully and was returned to his family group on day 33. The removal of affected tissue resulted in the loss of all pendulous portions of the throat sac, which creates a significant change in the physical appearance of an adult male orangutan. Follow-up observations revealed that the diminished capacity of the throat sac space had no effect on the animal’s ability to carry out normal male orangutan vocalizations. It is uncertain, however, whether the dramatic change in this animal’s secondary sex characteristics has changed the social dynamics of the group. Since the time of the surgery a 6-yr-old male in the group has developed aggressive behavior toward this dominant male (his sire).

Necrotizing fasciitis, also referred to as “flesh-eating bacteria” is a rare but life-threatening infection. It is often associated with group A streptococcal infections, but can be seen with many other bacteria including other streptococcal serotypes, polymicrobial infections and clostridial infections.¹ Once the infection is seeded, it proceeds with rapidly progressive inflammation and subsequent necrosis of the muscle fascia and surrounding tissues.² Mortality can be high. Early diagnosis followed by aggressive surgical debridement is essential to a successful outcome. In the case of this orangutan, immediate diagnosis of necrotizing fasciitis was hindered somewhat by the predilection of orangutans to throat sac infections. However, the rapid progression from onset to a life-threatening situation (less than 24 h) facilitated our diagnosis and encouraged us to proceed with immediate and life-saving surgical intervention.

Literature Cited

1.  Jallali, N. 2003. Necrotising fasciitis: its aetiology, diagnosis and management. J Wound Care. 12(8):297–300.

2.  Simonart, T. 2004. Group a beta-haemolytic streptococcal necrotizing fasciitis: early diagnosis and clinical features. Dermatology. 208:5–9.