OMENTAL TORSION IN A CAPTIVE POLAR BEAR (URSUS MARITIMUS) Author(s): Jose L. Mendez-Angulo, D.V.M., M.Sc., Dipl. A.C.V.S. (Large Animals), Francisco J. Funes, D.V.M., M.Sc., Ava M. Trent, D.V.M., Dipl. A.C.V.S., Michelle Willette, D.V.M., Kerry Woodhouse, B.V.Sc., Dipl. A.C.V.A. and Anna C. Renier, D.V.M., Dipl. A.C.V.I.M. Source: Journal of Zoo and Wildlife Medicine, 45(1):169-172. 2014. Published By: American Association of Zoo Veterinarians DOI: http://dx.doi.org/10.1638/2013-0077R.1 URL: http://www.bioone.org/doi/full/10.1638/2013-0077R.1
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Journal of Zoo and Wildlife Medicine 45(1): 169–172, 2014 Copyright 2014 by American Association of Zoo Veterinarians
OMENTAL TORSION IN A CAPTIVE POLAR BEAR (URSUS MARITIMUS) Jose L. Mendez-Angulo, D.V.M., M.Sc., Dipl. A.C.V.S. (Large Animals), Francisco J. Funes, D.V.M., M.Sc., Ava M. Trent, D.V.M., Dipl. A.C.V.S., Michelle Willette, D.V.M., Kerry Woodhouse, B.V.Sc., Dipl. A.C.V.A., and Anna C. Renier, D.V.M., Dipl. A.C.V.I.M.
Abstract: This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yrold, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen. Key words: Hemoabdomen, laparotomy, omentum, polar bear, Ursus maritimus, volvulus.
BRIEF COMMUNICATION Torsion of the omentum is a rare cause of acute abdominal pain in humans and animals.4,7–9,13 In mammals, the omentum is a fat-laden peritoneal remnant of mesogastrium from embryologic development and is anatomically divided into the greater and lesser omentum.5 Omental torsion is a condition in which a pedicle of the omental apron twists on its long axis sufficiently far as to cause omental vascular compromise. A diagnosis of primary omental torsion is made when no evidence of any other abdominal pathology is found intraoperatively.2 This condition has been reported in ,400 human cases8 and in one guinea pig (Cavia porcellus).13 Secondary omental torsion has been associated with abdominal tumors or adhesions in human patients.3 The only case of secondary omental torsion reported in veterinary species to date has been in an American badger (Taxidea taxus), in which case the torsion was due to omental adhesions caused by implantation of a radio transmitter.10 In this report, to the authors’ knowledge, the first case of omental torsion in a polar bear (Ursus maritimus) is reported. From the Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA (Mendez-Angulo, Funes, Trent, Willette, Woodhouse, Renier). Present address (Mendez-Angulo, Funes): Department of Animal Medicine and Surgery, College of Veterinary Medicine, University of Co´rdoba, Co´rdoba 14014, Spain. Correspondence should be directed to Dr. Mendez-Angulo ([email protected]).
A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center (VMC) for evaluation of possible gastrointestinal obstruction. Two days prior to presentation it showed signs of acute abdominal pain followed by lethargy, depression, and intermittent vomiting. On initial presentation at the zoo (Como Zoo, Minneapolis, Minnesota, 55103, USA) it was darted with medetomidine (Domitort, Pfizer Animal Health, Exton, Pennsylvania 19341, USA; 40 lg/kg i.m.) and ketamine (Ketasett, Fort Dodge Animal Health, Fort Dodge, Iowa 50501, USA; 2 mg/kg i.m.) and treated with enrofloxacin (Baytrilt, Bayer Healthcare LLC, Shawnee Mission, Kansas 66201, USA; 5 mg/kg i.m. s.i.d.) and crystalloid fluids (lactated Ringer’s solution [LRS], Baxter Healthcare, Deerfield, Illinois 60015, USA; 2 L s.q.). A blood sample taken at that time revealed mild hypochloremia (93 mM/L, reference range 94–118 mM/L).14 However, its condition deteriorated and it was anesthetized by dart with medetomidine and ketamine for transportation to the VMC. Upon arrival at the VMC, the bear was intubated orotracheally and maintained on inhalant anesthesia with isoflurane (Foranet, Baxter Healthcare Corporation) vaporized in 100% oxygen and delivered through a rebreathing circle system. The bear was allowed to breathe spontaneously and was monitored closely during anesthesia. She was estimated to be 6% dehydrated, and a 14G Teflon catheter (BD AngiocathTM, Becton Dickinson, New Jersey 07417, USA) was placed on the right hind dorsal pedal vein to
169
170
JOURNAL OF ZOO AND WILDLIFE MEDICINE
Figure 1. Intraoperative photograph of the exteriorized small intestine (caudal) and greater omentum (cranial). Note the section of the greater omentum that is twisted three to four times in a clockwise manner (arrow) and the discoloration of the necrotic, friable portion of the omentum distal to the torsion (arrowhead).
administer hypertonic saline (Hypertonic saline 7.2%, Bimeda-MTC Animal Health, Inc., Cambridge, Ontario, N3C 2W4, Canada; 0.5 L i.v.) as a bolus, followed by LRS at a rate of 20 ml/kg. Diagnostic procedures included a complete blood count, chemistry panel, peripheral lactate, gastroscopy, and abdominal ultrasound. Laboratory abnormalities on admission included a decreased packed cell volume (29.9%, reference range 32.0–55.7%),14 leukocytosis (white blood cells 18.54 3 103/ll, reference range 3.3–16.3 3 103/ll)14 with a left shift (bands 2.22 3 103/ll, reference range 0.0–1.53 3 103/ll);14 hypochloremia (84 mM/L); hyponatremia (124 mM/L, reference range 125–148 mM/L);14 hyperbilirubinemia (total bilirubin 7.7 mg/dl, reference range 0.0–0.8 mg/dl);14 elevated aspartate transferase (685 U/L, reference range 24–197 U/L);14 and moderate to marked acidosis (pH 7.212; pCO2 59.3 mm Hg; HCO3 23.8 mM/L [reference range 15–26 mM/L]; lactate 5.1 mM/L). Blood urea nitrogen (BUN) and creatinine were increased (92 mg/dl and 3.8 mg/dl; reference ranges 5–62 mg/dl and 0.5–2.4 mg/dl, respectively).14 Gastroscopy revealed no abnormalities of the stomach or esophagus. Abdominal ultrasound identified a large amount of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick sero-
sanguinous fluid compatible with hemoabdomen. Lactate of this fluid was 19.6 mM/L. Cytology of the peritoneal fluid revealed a marked neutrophilic exudate with moderate amounts of red blood cells and hemosiderin. Based on clinical signs, diagnostic imaging, and abdominocentesis, an exploratory laparotomy was recommended. Ampicillin (Polyflext, Boehringer Ingelheim, Inc., St. Joseph, Missouri 64506, USA; 10 mg/kg i.v.), enrofloxacin (5 mg/ kg), ketoprofen (Ketofent, Zoetis, Inc., Kalamazoo, Michigan 49007, USA; 3 mg/kg i.v.), and hydromorphone (Hydromorphone, Westward Pharmaceutical, Inc., Eatontown, New Jersey 07724, USA; 0.05 mg/kg i.v.) were given preoperatively. Immediately before surgery, a bolus of 2% lidocaine (Lidocaine hydrochloride 2%, Vedco, Inc., St. Joseph, Missouri 64507, USA; 2 mg/ kg i.v.) was administered and a continuous rate infusion (CRI; 30 lg/kg per hour i.v.) was continued throughout the surgical procedure. With the bear in dorsal recumbency, a 20-cm ventral midline skin incision centered at the umbilicus was made and the abdomen was explored systematically. Approximately 10 L of reddish-black, malodorous peritoneal fluid containing multiple large, necrotic blood clots was identified within and removed from the abdomen. The colon was found to be inflamed and hypomotile, with multiple areas of petechiation and hemorrhagic staining. It was lavaged copiously with LRS and replaced into the abdomen. A 10cm-diameter fluid-filled cavity was palpated on the right uterine horn, and centesis revealed a clear viscous fluid consistent with a uterine cyst. No abnormalities were detected on palpation of the spleen, liver, gall bladder, kidneys, ovaries, diaphragm, and small intestine. Sterile intraabdominal ultrasound of the liver and spleen parenchyma revealed no abnormalities. The ventral midline incision was extended 10 cm cranially and the greater omentum was exteriorized. A section of the greater omentum was found to be twisted on its long axis, three to four times in a clockwise manner, and the portion distal to the twist was necrotic (Fig. 1), with an adhered hematoma. The blood vessels proximal to the necrotic section of omentum were ligated individually with 2-0 polyglactin 910 (Vicrylt, Ethicon, Inc., Somerville, New Jersey 08876, USA), and the necrotic omental segment was resected using a LigaSuret (Covidien, Boulder, Colorado 80301, USA). The abdomen was lavaged with 12 L of warm LRS, which was removed by suction, and carboxymethylcellulose (Carboxymethylcellulose,
MENDEZ-ANGULO ET AL.—OMENTAL TORSION IN A CAPTIVE POLAR BEAR
Hercules, Inc., Wilmington, Delaware 19894, USA) was instilled into the abdomen to decrease the risk of adhesions to the colon. The linea alba was closed with 3 polyglactin 910, the subcutaneous with 0 polyglactin 910, and the skin with 0 polydioxanone (PDS II, Ethicon, Inc.); all layers were closed using a simple continuous pattern. The incision was covered with gauze and an Iobant (3M Health Care, St. Paul, Minnesota 55144, USA) adhesive drape to protect it during transportation of the animal back to the zoo. Intravenous boluses of propofol (PropofloTM, Abbott, North Chicago, Illinois 60064, USA; 280 mg [total dose] over 45 min) were given as needed to maintain anesthesia until the animal was back in her confinement at the zoo. Atipamezole (Antisedant, Pfizer Animal Health; 0.12 mg/kg i.m.) was administered to reverse any residual medetomidine. Recovery from anesthesia was prolonged (90 min) but was without complications. Postoperatively, ampicillin (10 mg/kg i.m. b.i.d. for 3 days), enrofloxacin (5 mg/kg i.m. s.i.d. for 6 days), ketoprofen (3 mg/kg i.m. s.i.d. for 3 days), and metoclopramide (Metoclopramide Injection, Hospira, Inc., Lake Forest, Illinois 60045, USA; 0.5 mg/kg i.m. s.i.d. for 2 days) were administered. Two days after surgery, the polar bear underwent a short anesthetic procedure (medetomidine 40 lg/kg i.m. and ketamine 2 mg/kg i.m.), during which a blood sample was collected and 6 L of LRS administered as an IV bolus. Blood work at this time showed mildly low red blood cell count (3.2 3 106/ll, reference range 3.9–8.6 3 106/ ll)14 and total protein (5.0 g/dl, reference range 6.3–11.4 g/dl)14 with persistent leukocytosis (16.4 3 103/ll) and a marked improvement in renal (BUN 45 mg/dl and creatinine 1.4 mg/dl), hepatic (total bilirubin 1.8 mg/dl and aspartate transferase 585 U/L), and electrolyte (chloride 101 mM/ L and sodium 135 mM/L) values. The bear continued to clinically improve and by 10 days postsurgery had recovered her normal appetite and activity. The bear was confined for 6 wk and was then returned to the larger exhibit with two other neutered male polar bears. Six months after surgery, the bear remained clinically normal and was transferred to another zoo under a breeding recommendation. Omental necrosis secondary to strangulation in an acquired umbilical hernia has been reported in three captive polar bears.15 However, to the authors’ knowledge, omental torsion has never been reported in polar bears. In humans, obesity, local trauma, large meals, or a rise in intra-
171
abdominal pressure from coughing or heavy exercise have been suggested to be predisposing factors for primary omental torsion.2,7,11,12 In the case presented here, the etiology of the torsion could not be determined. Clinical findings observed in the polar bear included abdominal pain, depression, vomiting, dehydration, electrolyte abnormalities, and leukocytosis, which are consistent with those reported in humans with an omental torsion.2,8,11 The only reported case13 of omental torsion in animals was in a guinea pig, whose main clinical signs were also similar to those reported in our case. These findings are common in a variety of gastrointestinal pathologies, and although imaging techniques have aided in the diagnosis of some human cases,1,11 a definitive diagnosis of omental torsion is most often made intraoperatively, as in the case described in this report. Similar serosanguineous effusions found in our case have been reported in both humans and guinea pigs with omental torsion.1,13 This is thought to be caused by engorgement of the tortuous omental vasculature, resulting in hemorrhagic extravasation into the peritoneal cavity. In our polar bear, rupture of the omental vasculature was identified in surgery, and blood loss was more severe than in other reported human cases.1 Surgical resection of the affected omentum (partial omentectomy) is considered the treatment of choice because it allows for removal of the necrotic segment of omentum and exploration of other abdominal organs. The prognosis with this technique is considered to be good in human cases.2,3,7,8,11 Possible complications reported in humans are adhesions, peritonitis, abscess formation, omental vasculature thrombosis, and omental necrosis if manual derotation is performed instead of omentectomy.6,8 In conclusion, the clinical presentation, medical and surgical treatment, and successful outcome of the first case of a polar bear with an omental torsion are presented. This report will facilitate the recognition of this condition in polar bears and help veterinarians to make clinical decisions in these patients. Acknowledgments: The authors thank all other veterinarians, technicians, zoo keepers, and students involved in the case.
LITERATURE CITED 1. Benaghmouch, F., E. M. Aalala, A. Hrora, A. Benamer, F. Sabbah, M. Ahallat, and M. Raiss. 2011.
172
JOURNAL OF ZOO AND WILDLIFE MEDICINE
Acute abdomen for omental torsion. Eur. J. Radiol. Extra 79: e55–e57. 2. Caprino, P., F. P. Prete, S. Alfieri, and G. B. Doglietto. 2004. Acute abdomen for omental volvulus. Am. J. Surg. 187: 268–269. 3. Cervellione, R. M., F. S. Camoglio, S. Bianchi, T. Balducci, G. Dipaola, L. Giacomello, C. Chironi, E. Erculiani, and A. Ottolenghi. 2002. Secondary omental torsion in children: report of two cases and review of the literature. Pediatr. Surg. Int. 18: 184–186. 4. Eitel, G. G. 1899. Rare omental torsion. N. Y. Med. Rec. 55: 715–716. 5. Liebermann-Meffert, D. 2000. The greater omentum. Anatomy, embryology, and surgical applications. Surg. Clin. North. Am. 80: 275–293, xii. 6. Nihei, Z., K. Kojima, K. Uehara, S. Sawai, M. Kakihana, R. Hirayama, and Y. Mishima. 1991. Omental bleeding with spontaneously derotated torsion—a case report. Jpn. J. Surg. 21: 700–702. 7. Pinedo-Onofre, J. A., and L. Guevara-Torres. 2007. Omental torsion. An acute abdomen etiology. Gac. Med. Mex. 143: 17–20. 8. Poujade, O., E. Ghiles, and A. Senasli. 2007. Primary torsion of the greater omentum: case report—review of literature: diagnosis cannot always be performed before surgery. Surg. Laparosc. Endosc. Percutan. Tech. 17: 54– 55.
9. Puylaert, J. B. 1992. Right-sided segmental infarction of the omentum: clinical, US, and CT findings. Radiology 185: 169–172. 10. Quinn, J. H., P. M. Gaffney, K. Gilardi, M. Murray, D. A. Jessup, and C. K. Johnson. 2010. Complication associated with abdominal surgical implantation of a radio transmitter in an American badger (Taxidea taxus). J. Zoo Wildl. Med. 41: 174–177. 11. Scabini, S., E. Rimini, A. Massobrio, E. Romairone, C. Linari, R. Scordamaglia, L. D. Marini, and V. Ferrando. 2011. Primary omental torsion: a case report. World J. Gastrointest. Surg. 3: 153–155. 12. Shields, P. G., and K. H. Chase. 1988. Primary torsion of the omentum in a jackhammer operator: another vibration-related injury. J. Occup. Med. 30: 892–894. 13. Shrubsole-Cockwill, A. N., K. R. Cockwill, and D. L. Parker. 2008. Omental torsion in a guinea pig (Cavia porcellus). Can. Vet. J. 49: 898–900. 14. Teare, J. A. (ed.). 2002. Physiological Data Reference Values. International Species Information System, Apple Valley, Minnesota. 15. Velguth, K. E., M. C. Rochat, J. N. Langan, and K. Backues. 2009. Acquired umbilical hernias in four captive polar bears (Ursus maritimus). J. Zoo Wildl. Med. 40: 767– 772.
Received for publication 21 April 2013
BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder.
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
Journal of Zoo and Wildlife Medicine 45(1): 169–172, 2014 Copyright 2014 by American Association of Zoo Veterinarians
OMENTAL TORSION IN A CAPTIVE POLAR BEAR (URSUS MARITIMUS) Jose L. Mendez-Angulo, D.V.M., M.Sc., Dipl. A.C.V.S. (Large Animals), Francisco J. Funes, D.V.M., M.Sc., Ava M. Trent, D.V.M., Dipl. A.C.V.S., Michelle Willette, D.V.M., Kerry Woodhouse, B.V.Sc., Dipl. A.C.V.A., and Anna C. Renier, D.V.M., Dipl. A.C.V.I.M.
Abstract: This is the first case report of an omental torsion in a polar bear (Ursus maritimus). A captive, 23-yrold, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center with a 2day history of lethargy, depression, and vomiting. Abdominal ultrasound identified large amounts of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick serosanguinous fluid compatible with a hemoabdomen. An exploratory laparotomy revealed a large amount of malodorous, serosanguineous fluid and multiple necrotic blood clots associated with a torsion of the greater omentum and rupture of a branch of the omental artery. A partial omentectomy was performed to remove the necrotic tissue and the abdomen was copiously lavaged. The polar bear recovered successfully and is reported to be clinically well 6 mo later. This condition should be considered as a differential in bears with clinical signs of intestinal obstruction and hemoabdomen. Key words: Hemoabdomen, laparotomy, omentum, polar bear, Ursus maritimus, volvulus.
BRIEF COMMUNICATION Torsion of the omentum is a rare cause of acute abdominal pain in humans and animals.4,7–9,13 In mammals, the omentum is a fat-laden peritoneal remnant of mesogastrium from embryologic development and is anatomically divided into the greater and lesser omentum.5 Omental torsion is a condition in which a pedicle of the omental apron twists on its long axis sufficiently far as to cause omental vascular compromise. A diagnosis of primary omental torsion is made when no evidence of any other abdominal pathology is found intraoperatively.2 This condition has been reported in ,400 human cases8 and in one guinea pig (Cavia porcellus).13 Secondary omental torsion has been associated with abdominal tumors or adhesions in human patients.3 The only case of secondary omental torsion reported in veterinary species to date has been in an American badger (Taxidea taxus), in which case the torsion was due to omental adhesions caused by implantation of a radio transmitter.10 In this report, to the authors’ knowledge, the first case of omental torsion in a polar bear (Ursus maritimus) is reported. From the Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, Saint Paul, MN 55108, USA (Mendez-Angulo, Funes, Trent, Willette, Woodhouse, Renier). Present address (Mendez-Angulo, Funes): Department of Animal Medicine and Surgery, College of Veterinary Medicine, University of Co´rdoba, Co´rdoba 14014, Spain. Correspondence should be directed to Dr. Mendez-Angulo ([email protected]).
A captive, 23-yr-old, 250-kg, intact female polar bear presented to the University of Minnesota Veterinary Medical Center (VMC) for evaluation of possible gastrointestinal obstruction. Two days prior to presentation it showed signs of acute abdominal pain followed by lethargy, depression, and intermittent vomiting. On initial presentation at the zoo (Como Zoo, Minneapolis, Minnesota, 55103, USA) it was darted with medetomidine (Domitort, Pfizer Animal Health, Exton, Pennsylvania 19341, USA; 40 lg/kg i.m.) and ketamine (Ketasett, Fort Dodge Animal Health, Fort Dodge, Iowa 50501, USA; 2 mg/kg i.m.) and treated with enrofloxacin (Baytrilt, Bayer Healthcare LLC, Shawnee Mission, Kansas 66201, USA; 5 mg/kg i.m. s.i.d.) and crystalloid fluids (lactated Ringer’s solution [LRS], Baxter Healthcare, Deerfield, Illinois 60015, USA; 2 L s.q.). A blood sample taken at that time revealed mild hypochloremia (93 mM/L, reference range 94–118 mM/L).14 However, its condition deteriorated and it was anesthetized by dart with medetomidine and ketamine for transportation to the VMC. Upon arrival at the VMC, the bear was intubated orotracheally and maintained on inhalant anesthesia with isoflurane (Foranet, Baxter Healthcare Corporation) vaporized in 100% oxygen and delivered through a rebreathing circle system. The bear was allowed to breathe spontaneously and was monitored closely during anesthesia. She was estimated to be 6% dehydrated, and a 14G Teflon catheter (BD AngiocathTM, Becton Dickinson, New Jersey 07417, USA) was placed on the right hind dorsal pedal vein to
169
170
JOURNAL OF ZOO AND WILDLIFE MEDICINE
Figure 1. Intraoperative photograph of the exteriorized small intestine (caudal) and greater omentum (cranial). Note the section of the greater omentum that is twisted three to four times in a clockwise manner (arrow) and the discoloration of the necrotic, friable portion of the omentum distal to the torsion (arrowhead).
administer hypertonic saline (Hypertonic saline 7.2%, Bimeda-MTC Animal Health, Inc., Cambridge, Ontario, N3C 2W4, Canada; 0.5 L i.v.) as a bolus, followed by LRS at a rate of 20 ml/kg. Diagnostic procedures included a complete blood count, chemistry panel, peripheral lactate, gastroscopy, and abdominal ultrasound. Laboratory abnormalities on admission included a decreased packed cell volume (29.9%, reference range 32.0–55.7%),14 leukocytosis (white blood cells 18.54 3 103/ll, reference range 3.3–16.3 3 103/ll)14 with a left shift (bands 2.22 3 103/ll, reference range 0.0–1.53 3 103/ll);14 hypochloremia (84 mM/L); hyponatremia (124 mM/L, reference range 125–148 mM/L);14 hyperbilirubinemia (total bilirubin 7.7 mg/dl, reference range 0.0–0.8 mg/dl);14 elevated aspartate transferase (685 U/L, reference range 24–197 U/L);14 and moderate to marked acidosis (pH 7.212; pCO2 59.3 mm Hg; HCO3 23.8 mM/L [reference range 15–26 mM/L]; lactate 5.1 mM/L). Blood urea nitrogen (BUN) and creatinine were increased (92 mg/dl and 3.8 mg/dl; reference ranges 5–62 mg/dl and 0.5–2.4 mg/dl, respectively).14 Gastroscopy revealed no abnormalities of the stomach or esophagus. Abdominal ultrasound identified a large amount of hyperechoic free peritoneal fluid. Ultrasound-guided abdominocentesis was performed and yielded thick sero-
sanguinous fluid compatible with hemoabdomen. Lactate of this fluid was 19.6 mM/L. Cytology of the peritoneal fluid revealed a marked neutrophilic exudate with moderate amounts of red blood cells and hemosiderin. Based on clinical signs, diagnostic imaging, and abdominocentesis, an exploratory laparotomy was recommended. Ampicillin (Polyflext, Boehringer Ingelheim, Inc., St. Joseph, Missouri 64506, USA; 10 mg/kg i.v.), enrofloxacin (5 mg/ kg), ketoprofen (Ketofent, Zoetis, Inc., Kalamazoo, Michigan 49007, USA; 3 mg/kg i.v.), and hydromorphone (Hydromorphone, Westward Pharmaceutical, Inc., Eatontown, New Jersey 07724, USA; 0.05 mg/kg i.v.) were given preoperatively. Immediately before surgery, a bolus of 2% lidocaine (Lidocaine hydrochloride 2%, Vedco, Inc., St. Joseph, Missouri 64507, USA; 2 mg/ kg i.v.) was administered and a continuous rate infusion (CRI; 30 lg/kg per hour i.v.) was continued throughout the surgical procedure. With the bear in dorsal recumbency, a 20-cm ventral midline skin incision centered at the umbilicus was made and the abdomen was explored systematically. Approximately 10 L of reddish-black, malodorous peritoneal fluid containing multiple large, necrotic blood clots was identified within and removed from the abdomen. The colon was found to be inflamed and hypomotile, with multiple areas of petechiation and hemorrhagic staining. It was lavaged copiously with LRS and replaced into the abdomen. A 10cm-diameter fluid-filled cavity was palpated on the right uterine horn, and centesis revealed a clear viscous fluid consistent with a uterine cyst. No abnormalities were detected on palpation of the spleen, liver, gall bladder, kidneys, ovaries, diaphragm, and small intestine. Sterile intraabdominal ultrasound of the liver and spleen parenchyma revealed no abnormalities. The ventral midline incision was extended 10 cm cranially and the greater omentum was exteriorized. A section of the greater omentum was found to be twisted on its long axis, three to four times in a clockwise manner, and the portion distal to the twist was necrotic (Fig. 1), with an adhered hematoma. The blood vessels proximal to the necrotic section of omentum were ligated individually with 2-0 polyglactin 910 (Vicrylt, Ethicon, Inc., Somerville, New Jersey 08876, USA), and the necrotic omental segment was resected using a LigaSuret (Covidien, Boulder, Colorado 80301, USA). The abdomen was lavaged with 12 L of warm LRS, which was removed by suction, and carboxymethylcellulose (Carboxymethylcellulose,
MENDEZ-ANGULO ET AL.—OMENTAL TORSION IN A CAPTIVE POLAR BEAR
Hercules, Inc., Wilmington, Delaware 19894, USA) was instilled into the abdomen to decrease the risk of adhesions to the colon. The linea alba was closed with 3 polyglactin 910, the subcutaneous with 0 polyglactin 910, and the skin with 0 polydioxanone (PDS II, Ethicon, Inc.); all layers were closed using a simple continuous pattern. The incision was covered with gauze and an Iobant (3M Health Care, St. Paul, Minnesota 55144, USA) adhesive drape to protect it during transportation of the animal back to the zoo. Intravenous boluses of propofol (PropofloTM, Abbott, North Chicago, Illinois 60064, USA; 280 mg [total dose] over 45 min) were given as needed to maintain anesthesia until the animal was back in her confinement at the zoo. Atipamezole (Antisedant, Pfizer Animal Health; 0.12 mg/kg i.m.) was administered to reverse any residual medetomidine. Recovery from anesthesia was prolonged (90 min) but was without complications. Postoperatively, ampicillin (10 mg/kg i.m. b.i.d. for 3 days), enrofloxacin (5 mg/kg i.m. s.i.d. for 6 days), ketoprofen (3 mg/kg i.m. s.i.d. for 3 days), and metoclopramide (Metoclopramide Injection, Hospira, Inc., Lake Forest, Illinois 60045, USA; 0.5 mg/kg i.m. s.i.d. for 2 days) were administered. Two days after surgery, the polar bear underwent a short anesthetic procedure (medetomidine 40 lg/kg i.m. and ketamine 2 mg/kg i.m.), during which a blood sample was collected and 6 L of LRS administered as an IV bolus. Blood work at this time showed mildly low red blood cell count (3.2 3 106/ll, reference range 3.9–8.6 3 106/ ll)14 and total protein (5.0 g/dl, reference range 6.3–11.4 g/dl)14 with persistent leukocytosis (16.4 3 103/ll) and a marked improvement in renal (BUN 45 mg/dl and creatinine 1.4 mg/dl), hepatic (total bilirubin 1.8 mg/dl and aspartate transferase 585 U/L), and electrolyte (chloride 101 mM/ L and sodium 135 mM/L) values. The bear continued to clinically improve and by 10 days postsurgery had recovered her normal appetite and activity. The bear was confined for 6 wk and was then returned to the larger exhibit with two other neutered male polar bears. Six months after surgery, the bear remained clinically normal and was transferred to another zoo under a breeding recommendation. Omental necrosis secondary to strangulation in an acquired umbilical hernia has been reported in three captive polar bears.15 However, to the authors’ knowledge, omental torsion has never been reported in polar bears. In humans, obesity, local trauma, large meals, or a rise in intra-
171
abdominal pressure from coughing or heavy exercise have been suggested to be predisposing factors for primary omental torsion.2,7,11,12 In the case presented here, the etiology of the torsion could not be determined. Clinical findings observed in the polar bear included abdominal pain, depression, vomiting, dehydration, electrolyte abnormalities, and leukocytosis, which are consistent with those reported in humans with an omental torsion.2,8,11 The only reported case13 of omental torsion in animals was in a guinea pig, whose main clinical signs were also similar to those reported in our case. These findings are common in a variety of gastrointestinal pathologies, and although imaging techniques have aided in the diagnosis of some human cases,1,11 a definitive diagnosis of omental torsion is most often made intraoperatively, as in the case described in this report. Similar serosanguineous effusions found in our case have been reported in both humans and guinea pigs with omental torsion.1,13 This is thought to be caused by engorgement of the tortuous omental vasculature, resulting in hemorrhagic extravasation into the peritoneal cavity. In our polar bear, rupture of the omental vasculature was identified in surgery, and blood loss was more severe than in other reported human cases.1 Surgical resection of the affected omentum (partial omentectomy) is considered the treatment of choice because it allows for removal of the necrotic segment of omentum and exploration of other abdominal organs. The prognosis with this technique is considered to be good in human cases.2,3,7,8,11 Possible complications reported in humans are adhesions, peritonitis, abscess formation, omental vasculature thrombosis, and omental necrosis if manual derotation is performed instead of omentectomy.6,8 In conclusion, the clinical presentation, medical and surgical treatment, and successful outcome of the first case of a polar bear with an omental torsion are presented. This report will facilitate the recognition of this condition in polar bears and help veterinarians to make clinical decisions in these patients. Acknowledgments: The authors thank all other veterinarians, technicians, zoo keepers, and students involved in the case.
LITERATURE CITED 1. Benaghmouch, F., E. M. Aalala, A. Hrora, A. Benamer, F. Sabbah, M. Ahallat, and M. Raiss. 2011.
172
JOURNAL OF ZOO AND WILDLIFE MEDICINE
Acute abdomen for omental torsion. Eur. J. Radiol. Extra 79: e55–e57. 2. Caprino, P., F. P. Prete, S. Alfieri, and G. B. Doglietto. 2004. Acute abdomen for omental volvulus. Am. J. Surg. 187: 268–269. 3. Cervellione, R. M., F. S. Camoglio, S. Bianchi, T. Balducci, G. Dipaola, L. Giacomello, C. Chironi, E. Erculiani, and A. Ottolenghi. 2002. Secondary omental torsion in children: report of two cases and review of the literature. Pediatr. Surg. Int. 18: 184–186. 4. Eitel, G. G. 1899. Rare omental torsion. N. Y. Med. Rec. 55: 715–716. 5. Liebermann-Meffert, D. 2000. The greater omentum. Anatomy, embryology, and surgical applications. Surg. Clin. North. Am. 80: 275–293, xii. 6. Nihei, Z., K. Kojima, K. Uehara, S. Sawai, M. Kakihana, R. Hirayama, and Y. Mishima. 1991. Omental bleeding with spontaneously derotated torsion—a case report. Jpn. J. Surg. 21: 700–702. 7. Pinedo-Onofre, J. A., and L. Guevara-Torres. 2007. Omental torsion. An acute abdomen etiology. Gac. Med. Mex. 143: 17–20. 8. Poujade, O., E. Ghiles, and A. Senasli. 2007. Primary torsion of the greater omentum: case report—review of literature: diagnosis cannot always be performed before surgery. Surg. Laparosc. Endosc. Percutan. Tech. 17: 54– 55.
9. Puylaert, J. B. 1992. Right-sided segmental infarction of the omentum: clinical, US, and CT findings. Radiology 185: 169–172. 10. Quinn, J. H., P. M. Gaffney, K. Gilardi, M. Murray, D. A. Jessup, and C. K. Johnson. 2010. Complication associated with abdominal surgical implantation of a radio transmitter in an American badger (Taxidea taxus). J. Zoo Wildl. Med. 41: 174–177. 11. Scabini, S., E. Rimini, A. Massobrio, E. Romairone, C. Linari, R. Scordamaglia, L. D. Marini, and V. Ferrando. 2011. Primary omental torsion: a case report. World J. Gastrointest. Surg. 3: 153–155. 12. Shields, P. G., and K. H. Chase. 1988. Primary torsion of the omentum in a jackhammer operator: another vibration-related injury. J. Occup. Med. 30: 892–894. 13. Shrubsole-Cockwill, A. N., K. R. Cockwill, and D. L. Parker. 2008. Omental torsion in a guinea pig (Cavia porcellus). Can. Vet. J. 49: 898–900. 14. Teare, J. A. (ed.). 2002. Physiological Data Reference Values. International Species Information System, Apple Valley, Minnesota. 15. Velguth, K. E., M. C. Rochat, J. N. Langan, and K. Backues. 2009. Acquired umbilical hernias in four captive polar bears (Ursus maritimus). J. Zoo Wildl. Med. 40: 767– 772.
Received for publication 21 April 2013
