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Year: 2008

Nonsurgical treatment of a bilateral mandibular fracture in ablue-tongued skink

Köchli, B; Schmid, N; Hatt, J M; Dennler, M; Steinmetz, H W

Köchli, B; Schmid, N; Hatt, J M; Dennler, M; Steinmetz, H W (2008). Nonsurgical treatment of a bilateralmandibular fracture in a blue-tongued skink. Exotic DVM, 10(2):25-28.Postprint available at:http://www.zora.uzh.ch

Posted at the Zurich Open Repository and Archive, University of Zurich.http://www.zora.uzh.ch

Originally published at:Exotic DVM 2008, 10(2):25-28.

Köchli, B; Schmid, N; Hatt, J M; Dennler, M; Steinmetz, H W (2008). Nonsurgical treatment of a bilateralmandibular fracture in a blue-tongued skink. Exotic DVM, 10(2):25-28.Postprint available at:http://www.zora.uzh.ch

Posted at the Zurich Open Repository and Archive, University of Zurich.http://www.zora.uzh.ch

Originally published at:Exotic DVM 2008, 10(2):25-28.

MANDIBULAR FRACTURE IN A BLUE TONGUED SKINK 1

Treatment of a Bilateral Mandibular Fracture in a Blue-tongued Skink Barbara Köchli, cand. med. vet., Nicole Schmid, Dr. med. vet., Jean-Michel Hatt, Prof. Dr. Med. vet. Dipl. ECAMS, Dipl. ACZM, Matthias Dennler, Dr. med. vet., Hanspeter W. Steinmetz, Dr. med. vet., M.Sc. Clinic of Zoo Animals, Exotic Pets and Wildlife (Köchli, Schmid, Hatt, Steinmetz,), Division of Diagnostic Imaging and Radio-Oncology (Dennler), Vetsuisse Faculty, University of Zürich, Switzerland Blue-tongued skinks (Tiliqua scincoides) are commonly seen exotic pets in veterinary clinics. The most common disorders include dysecdysis and metabolic bone disease.10 While mandibular fractures are reported in various mammalian species, only two cases of mandibular fracture were found in the literature.11, 17 Nevertheless, mandibular fractures are documented in fossil reptiles and were suspected as an important cause of death in the past.4 Various treatment options are well documented in domestic animals.3, 13, 15 Both in the literature described reptile cases had a surgical approach. The open fracture in the lizard was treated with a combination of non-absorbable suture material and an intramedullary pin.17 Fracture healing in the turtle was accomplished with pins inserted in the ramus mandibularis followed by a bone plate fixation on each ramus.11 The current case report documents a successful, non-surgical treatment approach of an open, bilateral mandibular fracture in a blue-tongued skink.

Case Report A 1.5-year-old male blue-tongued skink was presented to the veterinary clinic of the Clinic of Zoo Animals, Exotic Pets and Wildlife, University of Zurich, Switzerland due to anorexia and an injury on the right lower jaw. On the initial examination the skink’s body condition was good, and a superficial wound on the ventrorostral aspect of lower jaw, contaminated with sand, was found. A slight swelling was present that appeared soft and elastic on palpation. There was an instability involving both mandibles. For further work-up anesthesia was induced with 0.2 mg/kg medetomidine hydrochloride (Domitor®, Pfizer AG) and 1.1 mg/kg ketamine hydrochloride (Ketasol-100®, Dr. E. Gräub AG) mixed together and injected intramuscularly in the right front leg. Anesthesia was maintained with 1.5% isoflurane (Attane,™ Provet) in oxygene delivered by face mask. In addition, 1 mg/kg butorphanol (Morphasol-4, Dr. E. Graeub AG) were given intramuscularly for analgesia. Whole body and skull radiographs in laterolateral and dorsoventral views were obtained. In addition, a digital dental film was positioned as far as possible caudally in the mouth for ventrodorsal open-mouthed radiographs of the mandible (Fig 1). Radiographs revealed a disrupted outline of the Pars horizontalis of the mandible. The fracture line was oblique with a narrow pointed end ventrocaudally, and osteolysis was

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suspected. No fragments were observed. Mineralization of the skeleton was moderate. Multiple older rib fractures were visible. Moderate dislocation and a small callus were present around the ends of the fractured ribs. Based on physical examination and radiographs, the diagnosis was formulated of an open, bilateral mandibular fracture and multiple rib fractures as a result of malnutrition and trauma. An intraoral plate reaching over all teeth to the corner of the mouth was adapted, and a tape muzzle was applied in order to stabilize the fracture (Fig 2). The plate was made of 2 mm thick plastic and was cut into a U shape in order to leave more space for tongue movements (Fig 3). Two bands of tape were applied. The first tape was placed around the mandible and maxilla just caudal to the nares and in front of the eyes to reduce vertical and horizontal forces. The second tape went from the ventrorostral part of the mandible ascending in an angle behind both eyes. For regular feeding and medication an esophagostomy tube was placed in the left lateral neck region as described in chelonians.14 A soft padded (Soffban® Synthetic, BSN medical) bandage (Coban™, 3M) was put around neck and thorax to hold the tube in place and protect the surgery wound. One hundred minutes after induction the medetomidine hydrochloride was reversed with 0.2 mg/kg atipamezole hydrochloride IM (Antisedan®, Dr. E. Gräub AG). The skink was placed on a towel covered heating pad in an 80x40x50cm terrarium for recovery. Temperature was maintained by 28°C with a heating lamp providing a hot spot in one corner of 35°C. The enclosure had no furniture to prevent injuries during recovery. Post-surgical treatment included analgesics (0.2 mg/kg meloxicam PO q24h for 14d, Metacam® 5 mg/ml, Boehringer Ingelheim) and antibiotic treatment (10 mg/kg marbofloxacin PO q24h for 7d, Marbocyl,® Vétoquinol AG). Additional treatment included 600 mg/kg sucralfate PO (Ulcogant®, Merck AG) for the prevention of gastric ulcers. The wound was cleaned with a cotton tip soaked in 0.2% Polyhexanidum solution (Lavasept, Fresenius) for 7 days. The animal was fed through the esophagostomy tube with a special diet (Carnivore Care mixed with Critical Care 1:1, both from Oxbow Pet Products) every other day. Feeding dose was titrated that the animal did not loose any body weight (approx. 2-5ml/d). The fracture healing process and nutritional status were monitored by monthly radiographs and daily weight status, respectively. During the first week of treatment, petechias appeared in the ventral skin of the animal and were interpreted as septicemia. The hemorrhages resolved during antibiotic treatment (10 mg/kg enrofloxacin PO q24h for 14d, Baytril 2.5%, Bayer HealthCare). The tape bandage around the mouth was changed under general isoflurane anesthesia delivered by face mask for local wound control after 7 days. At this time the animal was in good general condition and stable in weight. The wound was clean and almost closed by granulation tissue.

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Twenty-eight days after surgery the wound had healed, and radiologic examination revealed a slightly widened fracture gap. Fracture alignment was stationary and no clear callus formation was noticeable. When the intraoral plate and tape muzzle were removed 36 days after application, radiographs showed a more narrow fracture fissure. The fracture seemed to be stable on palpation in the left mandible but still unstable in the right. The animal was starting to lose teeth bilaterally over the fracture sites; therefore, the intraoral plate and tape muzzle were removed. Forty-four days after surgery the animal started to eat by itself, and feeding by esophagostomy tube was stopped. During treatment it was detected that the blue-tongued skink was reluctant to use its front legs and showed severe, bilateral front leg lameness. Radiology showed no abnormalities of the pectoral girdle and the front legs. Pressure from the bandage around the neck and thorax, holding the esophagostomy tube in place, was suspected. After the bandage was removed the animal started to use its front legs normally within 4 days. Seventy days after surgery the fracture was still clearly visible, although callus production was seen ventrally on both mandibles on radiologic examination (Fig 4); especially the right mandible remained in a slightly oblique position. Nevertheless, the fracture was stable on palpation. Blood chemistry and hematology values were within reference ranges.2 The skink ate regularly and the esophagostomy tube was removed. The animal was released from veterinary care in good condition with normal feeding behavior after 12 weeks of initial therapy. Discussion The present case describes the first successful non-surgical treatment of a mandibular fracture in a blue-tongued skink. Fracture healing in reptiles is slower in comparison to birds and mammals.1 Healing time for traumatic fractures is generally 6-18 months. Pathologic fractures that result from a metabolic bone disease seem to heal more rapidly (6-8 weeks) if the inciting problem is corrected.1 The difference in healing time may be explained that in case of metabolic bone disease the bones are in need of calcium and ready to build more bone material even before the fracture occurs, while normal bones need to get ready for bone building first. In the present case it was not possible to identify the cause of the fracture. The presence of poor calcification of the skeleton, several broken ribs in radiology and the relatively fast healing time seem to support that a combination of metabolic bone disease and rough handling might have caused the mandibular fracture. In the course of treatment the skink lost several teeth around both fracture sites. In the present case metabolic bone disease, osteomyelitis or severe gingivitis might have caused the tooth loss in the blue-tongued skink. Considering that the skink is a pleurodont reptile metabolic bone disease is not likely the cause for the loss of teeth as the teeth are not embedded in the bone.16 Osteomyelitis was not considered as the

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cause for the same reason. The most possible reason for the loss of teeth is that the animal developed gingivitis. The skink had an open fracture perforating intraoral mucosal membranes and it is suspected that bacteria may have caused the gingivitis through these lesions. Gingivitis sometimes is hard to detect in skinks as the only symptom may be a slight swelling around the teeth. Vascular damage cannot be ruled out. Damage could have occurred through the fracture itself or the swelling might have compressed the vessels and therefore caused necrosis in the surrounding tissue resulting in tooth loss as the teeth lost their stability. Petechia appeared on the ventral surface of the animal during the first week of treatment. Generalized spots of minor hemorrhage in the skin of reptiles are interpreted as a serious clinical sign, and septicemia is suspected.1 Hemorrhages are caused by vasculitis. Although the animal was treated aggressively with systemic antibiotics from the beginning, petechia developed 7 days after treatment onset. This might be caused due to the slow metabolism in reptiles. Microflora of the mouth is known to harbour various bacteria, which can cause severe infections.5, 7, 9, 12 In addition, mandibular fractures are generally considered open fractures perforating the mucosal membrane. Therefore it is imperative to treat all mandibular fractures with a broad spectrum antibiotic. In the current case antimicrobial treatment was started several days after fracture and / or wound occurrence and possible septicaemia developed during the healing process. As described in other species6, 8 the open, bilateral mandibular fracture in a blue-tongued skink was successfully treated with a tape muzzle in combination with an oral plate. Due to potential systemic infection preventative antimicrobial treatment is necessary and the placement of an esophagostomy tube for nutritional support is recommended. Acknowledgments The authors thank Sandra Mosimann, Sabrina Riedle and Sarah Scharmer and all other animal care staff at the veterinary clinic, Vetsuisse Faculty, University of Zurich, Switzerland, for the animal care and their help during the procedures.

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References and Further Reading 1. Bennett, R. A., R. S. Funk, K. T. Fitzgerald, R. Vera and S. J. Hernandez-Divers. 2006. Surgery. In: Mader, D. R. (ed.). Reptile Medicine and Surgery, 2. W.B. Saunders Co., Philadelphia, PA. Pp: 599-609. 2. Carpenter, J. W. 2005. Hematologic and serum biochemical values of reptiles. In: Exotic animal formulary, 3. Elsevier, St. Louis, MO. Pp: 94-108. 3. Davidson, J. R. and M. S. Bauer. 1992. Fractures of the mandible and maxilla. Vet Clin North Am Small Anim Pract. 22: 109-119. 4. Evans, S. E. 1983. Mandibular fracture and inferred behaviour in a fossile reptile. Copeia. 845-847. 5. Flandry, F., E. J. Lisecki, G. J. Domingue, R. L. Nichols, D. L. Greer and R. J. Haddad, Jr. 1989. Initial antibiotic therapy for alligator bites: characterization of the oral flora of Alligator mississippiensis. South Med J. 82: 262-266. 6. Howard, P. E. 1981. Tape muzzle for mandibular fractures. Vet Med Small Anim Clin. 76: 517-519. 7. Hsieh, S. and F. E. Babl. 1999. Serratia marcescens cellulitis following an iguana bite. Clin Infect Dis. 28: 1181-1182. 8. Johnson, A. L. and D. A. Hulse. 2002. Management of specific fractures. In: Fossum, T. W. (ed.). Small Animal Surgery, 2. Mosby, St. Louis, MO. Pp: 901-913. 9. Kelsey, J., M. Ehrlich and S. O. Henderson. 1997. Exotic reptile bites. Am J Emerg Med. 15: 536-537. 10. Kottwitz, J. 2007. Clinician's quick reference guide to selected captive exotic species. Exotic DVM. 8: 21-44. 11. Kuehn, G. 1972. Bilateral transverse mandibular fractures in a turtle. Proc. American Association of Zoo Veterinarians. 243. 12. Merin, D. S. and S. P. Bush. 2000. Severe hand injury following a green iguana bite. Wilderness Environ Med. 11: 225-226. 13. Nap, R. C., B. P. Meij and H. A. Hazewinkel. 1994. [Mandibular and maxillary fractures in dogs and cats]. Tijdschr Diergeneeskd. 119: 456-462. 14. Norton, T. M. 2005. Chelonian emergency and critical care. Seminars in Avian and Exotic Pet Medicine. 14: 106-130.

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15. Nuss, K., R. Kostlin, E. Elma and U. Matis. 1991. [Mandibular fractures in cattle--treatment and results]. Tierarztl Prax. 19: 27-33. 16. O'Malley, B. 2005. Lizards. In: O'Malley, B. (ed.). Clinical anatomy and physiology of exotic species, Elsevier Saunders, Edinburgh, U.K. Pp: 57-75. 17. Scheelings, T. F. 2008. Surgical management of maxillary and mandibulary fractures in an Eastern bluetongue skink, Tiliqua scincoides scincoides. J Herp Med Surg 17: 136-140.

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Figures Fig 1. Right lateral radiograph of the skull (a) and open-mouthed ventrodorsal radiograph (b) of the mandible of a blue-tongued skink. Radiographs revealed a disrupted outline of the Pars horizontalis of the mandible. The fracture line was oblique with a narrow pointed end ventrocaudally and osteolysis was suspected. There were no fragments found. Fig 2. A 1.5-year-old blue-tongued skink with an open, bilateral mandibular fracture after tape muzzle and intraoral plate fixation. An esophagostomy tube was placed in the left lateral neck region for regular feeding. Fig 3. The intraoral plate used for an open, bilateral mandibular fracture in a skink was made of 2 mm-thick plastic and was cut into a U-shape in order to leave more space for tongue movements. Fig 4. Right lateral radiograph of the skull (a) and open-mouthed ventrodorsal radiograph (b) of the mandible of the skink 10 weeks after tape muzzle fixation. The fracture was still clearly visible, although callus production can be seen ventrally on both mandibles.

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Figure 1a

Figure 1b

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Figure 2a

Figure 2b

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Figure 3

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Figure 4a

Figure 4b

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