Abstract

Bacterial osteomyelitis has been documented in green,¹ leatherback² and cold-stunned Kemp's ridley sea turtles, often associated with systemic disease^3,4. Although this condition may already be present at time of stranding in some patients, clinical signs associated with osteomyelitis (including lethargy, anorexia, swelling and lameness³) may develop several weeks to months into rehabilitation. Initial diagnostic tests include physical examination, blood work, diagnostic imaging. The objectives of this study were to summarize clinical findings in three green (Chelonia mydas, Cm) and one Kemp's ridley sea turtle (Lepidochelys kempii, Lk) with diagnosis of osteomyelitis at different anatomical locations.

Case 1 (Cm) presented with a severe carapace fracture off the midline, exposing the coelomic cavity and cranial vertebrae. Initial treatment included vacuum-assisted wound closure therapy for five months. Osteomyelitis of the right elbow then followed by the left shoulder was diagnosed 40 days into rehabilitation. Synovial fluid cytology from the right elbow was consistent with marked heterophilic inflammation. Bacterial culture of the joint fluid revealed Enterococcus spp. Numerous fibropapillomatosis (FP) lesions developed months later, and the patient was euthanized because of diagnosis of internal FP by CT imaging.

Case 2 (Cm) was emaciated with anorexia, ileus with associated buoyancy, and a healed wound on the cranial part of the carapace. Scapular osteomyelitis was diagnosed 2 months into rehabilitation. The patient developed multiple, small external FP lesions and was unable to recover from anesthesia one year into rehabilitation to remove FP tumors. Gross necropsy confirmed severe chronic scapulohumeral joint osteomyelitis.

Case 3 (Cm) was admitted with a monofilament fishing line entanglement of the proximal aspect of the humerus. Due to severe vascular compromise, the flipper was amputated, leaving only the humeral head in place. Culture of the necrotic bone and surrounding tissue identified Citrobacter freundii and Providencia rettgeri. After 18 months of rehabilitation, physical examination and radiographic imaging revealed osteomyelitis of the contralateral humeral head. Joint fluid cytology diagnosed moderate mononuclear inflammation, consistent with non-inflammatory joint disease. The patient is currently in rehabilitation and doing well.

Case 4 (Lk) was admitted with lethargy, multiple carapace lesions, and an old cranial carapace fracture. Two months after admission, the patient developed sudden onset of lameness and anorexia. Severe osteomyelitis of the humeral head and contralateral elbow was diagnosed by radiography. Synovial fluid and blood culture repeatedly revealed Enterococcus faecalis and Serratia marcescens with progression of osteomyelitis to the cervical vertebrae (C8) and bilateral femoral head despite intensive therapy. The patient was euthanized due to poor prognosis.

All four sea turtles were admitted with history of trauma and concomitant medical issues, with ultimate development of osteomyelitis after a minimum of 40 days into rehabilitation. In contrast to cold-stunned Kemp's ridley sea turtles, which are often affected by Enterococcus spp.,³ the patients presented herein had history of trauma and various pathogenic bacteria were isolated. The pathophysiology of post-traumatic osteomyelitis remains unknown, with vascular insufficiency and local trauma presenting potential initiating factors in growing animals, similar to children.⁵ Better understanding of the pathologic process would concur to improve therapeutic strategy.

Acknowledgments

The authors would like to thank the dedicated staff and volunteers at the Georgia Sea Turtle Center for the amazing care provided to the animals.

* Presenting author
⁺ Student presenter

Literature Cited

1.  Guthrie A, George J, deMaar TW. Bilateral chronic shoulder infections in an adult green sea turtle (Chelonia mydas). Journal of Herpetological Medicine and Surgery. 2010;20(4):105–108.

2.  Ogden JA, Rhodin AG, Conlogue GJ, Light TR. Pathobiology of septic arthritis and contiguous osteomyelitis in a leatherback turtle (Dermochelys coriacea). Journal of Wildlife Diseases. 1981;17(2):277–287.

3.  Innis CJ, Braverman H, Cavin JM, et al. Diagnosis and management of Enterococcus spp. infections during rehabilitation of cold-stunned Kemp's ridley turtles (Lepidochelys kempii): 50 cases (2006–2012). Journal of the American Veterinary Medical Association. 2014;245:315–323.

4.  Greer LL, Strandberg JD, Whitaker BR. Mycobacterium chelonae osteoarthritis in a Kemp's ridley sea turtle (Lepidochelys kempii). Journal of Wildlife Diseases. 2003;39:736–741.

5.  Kabak S, Tuncel M, Halici M, Tutuş A, Baktir A, Yildirim C. Role of trauma on acute haematogenic osteomyelitis aetiology. European Journal of Emergency Medicine: Official Journal of the European Society for Emergency Medicine. 1999;6(3):219–222.