Veterinary Medicine - September 2008 - (Page 503)

was 7 cm in diameter at its largest, which is larger than any previously described cranial mediastinal cyst (the closest being 5 cm in diameter).6 The larger size of the cyst in this case may have played a role in causing cranial vena cava compression and a secondary chylothorax. However, because the chylothorax recurred after the thymic cyst was removed, it cannot be proven. A difﬁcult case to treat We attempted to medically manage the chylothorax by reducing the fat content of the cat’s diet and performing intermittent thoracentesis, with the hope that if the thoracic duct had been disrupted during the thymic cyst surgery, it would heal with time. We discussed the potential bene t of rutin, but the owner elected not to pursue this option. The chylothorax appeared to be resolving based on the decreased amount of effusion being drained compared with the amount drained at the initial presentation and in the rst 12 hours after the rst surgery. However, when the effusion suddenly became severe and life-threatening again, it was clear that thoracic duct ligation and partial pericardiectomy were indicated. After the thoracic duct ligation and partial pericardiectomy, the cat developed a serosanguineous effusion in the immediate postoperative period. This type of effusion has been seen in people, dogs, and cats after a thoracic duct ligation.1,2 A partial pericardiectomy has been shown in some cases to resolve this type of uid accumulation. Since a partial pericardiectomy had already been performed, we had to consider medically treating the effusion. Somatostatin analogues have been used successfully to treat chylothorax in people with traumatic or postoperative chylothorax. Somatostatin decreases jejunal secretion, prolongs gastrointestinal transit time, stimulates gastrointestinal water absorption, and inhibits biliary, pancreatic, and gastrointestinal secretions. The reduction of gastrointestinal secretions may help heal the thoracic 4. The Companion Port; tubing from a Veterinary Pneumothorax Set is secured with nonabsorbable suture to the port (A); a noncutting 22-ga needle and right-angle infusion set with an attached 5-ml syringe (B); and a packet of benzethonium chloride cleansing solution (C). in more than three dogs and in one cat. However, we sometimes replace the existing silicone catheter with the tubing (8.3-F, 35-cm catheter) from a Veterinary Pneumothorax Set (SurgiVet) to facilitate repeated uid aspiration. We secure the chest tube to the Companion Port implantable access port with nonabsorbable suture material. This titanium reservoir, similar to a small metal cup, is covered by a dense silicone septum that allows access to the interior reservoir. The port is surgically placed in the subcutaneous layer, and the chest tube is passed into the thoracic cavity. The caregiver palpates the port through the patient’s skin and uses a noncutting 22-ga needle and right-angle infusion set to drain the chest after aseptically preparing the skin over the port with a benzethonium chloride cleansing solution (Figure 4). CONCLUSION duct by decreasing the lymphatic ow within the duct.1,2 In addition, in dogs that had experimental thoracic duct transection, somatostatin therapy produced an early decrease in drainage as well as early stula closure.8 It is unknown whether somatostatin is effective in cases of nontraumatic chylothorax, but in dogs and cats receiving octreotide (a synthetic somatostatin analogue), chyle and postoperative serosanguineous effusion have resolved.1,2,8 During the initial few weeks after the thoracic duct ligation and partial pericardiectomy, the cat was brought in for intermittent thoracentesis. We considered using octreotide, but within a few weeks, the uid accumulation appeared to be decreasing, so we decided not to administer it. Although in this case our patient did not bene t at home from our use of the Companion Port because of owner noncompliance, this device has been useful in other cases. The subcutaneously implanted device is typically used for repeated vascular access. We have successfully used it as an indwelling chest tube for more than three months This case demonstrates the medical and surgical treatments for chylothorax. This cat’s chylothorax could have been idiopathic or it could have been secondary to disruption of lymphatic drainage due to the large thymic cyst. If the cyst had caused the chyle accumulation, its reaccumulation after cyst removal could be explained by iatrogenic duct disruption. However, based on the literature, cranial mediastinal cysts are often incidental ndings that do not cause chylothorax and do not require surgical removal. REFERENCES 1. Fossum TW. Chylothorax: pathophysiology and treatment options, in Proceedings. 24th Annual Am Coll Vet Intern Med Forum 2006. 2. Fossum TW, Mertens MM, Miller MW, et al. Thoracic duct ligation and pericardectomy for treatment of idiopathic chylothorax. J Vet Intern Med 2004;18(3):307-310. 3. Fossum TW. Chylothorax. In: King LG, ed. Respiratory disease in dogs and cats. St. Louis, Mo: WB Saunders 2004:597-604. 4. Casley-Smith JR, Mogan RG, Piller NB. Treatment of lymphedema of the arms and legs with 5,6-benzo-(alpha)-pyrone. N Engl J Med 1993;329(16):1158-1163. 5. Kopko SH. The use of rutin in a cat with idiopathic chylothorax. Can Vet J 2005;46(8):729-731. 6. Zekas LJ, Adams WM. Cranial mediastinal cysts in nine cats. Vet Radiol Ultrasound 2002;43(5):413-418. 7. Liu S, Patnaik AK, Burk RL. Thymic branchial cysts in the dog and cat. J Am Vet Med Assoc 1983;182(10):1095-1098. 8. Markham KM, Glover JL, Welsh RJ, et al. Octreotide in the treatment of thoracic duct injuries. Am Surg 2000;66(12):1165-1167. VETERINARY MEDICINE September 2008 503

Table of Contents Feed for the Digital Edition of Veterinary Medicine - September 2008

Veterinary Medicine - September 2008 Contents Leading Off Practical Matters Idea Exchange A Challengin Case: Thymic Cyst and Recurrent Chylothorax in a Cat 10 Life-Threatening Behavior Myths CE Form Advertiser Index Marketplace/Classifieds Mind Over Miller

Veterinary Medicine - September 2008

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