Syndrome of Inappropriate Antidiuretic Hormone in a Bulldog with Aspiration Pneumonia

A 15-week-old, male intact, 9.8 kg English Bulldog presented to the University of Georgia Veterinary Teaching Hospital (VTH) for surgical correction of presumed brachycephalic airway syndrome. For 3 weeks before admission, the dog experienced stertorous breathing that was not responsive to antibiotic treatment, including doxycycline, cefpodoxime, and marbofloxacin, for treatment of presumptive pneumonia. Thoracic radiographs performed a week before presentation disclosed a hypoplastic trachea and tracheal collapse, but no evidence of pneumonia. Baermann testing of feces did not identify parasites. On presentation, the puppy had loud referred upper airway noise and stertorous breathing on auscultation. The nares were stenotic bilaterally. Preoperative laboratory assessment was normal. Serum electrolyte concentrations were not measured. An upper airway examination was performed under propofol anesthesia, and disclosed a moderately elongated soft palate and everted laryngeal saccules, indicating grade 1 laryngeal collapse. The dog was intubated and maintained under anesthesia using isoflurane in 100% oxygen. A CO2 laser was used to perform a staphylectomy and metzenbaum scissors were used to perform laryngeal sacculectomy. A bilateral rhinoplasty was performed with the CO2 laser. Upon recovery, the dog was eupneic but its breathing remained stertorous; however, he seemed comfortable and eupneic. The dog was maintained on lactated ringer’s solution during anesthesia and surgery at a rate of 10 mL/kg/h, which was discontinued upon extubation. The postoperative course was complicated by several episodes of regurgitation, which were temporally associated with administration of hydromorphone (0.05 mg/ kg IV q4h). Overnight, progressive respiratory distress developed and 12 h after surgery, the dog became orthopneic, with dull mentation. The puppy was transferred to an oxygen cage with a fractional inspired oxygen concentration of 40%. Thoracic radiographs identified severe alveolar disease in both the left cranial lung lobe and the right middle lung lobe. Plasma electrolyte concentrations were measured and identified moderate hyponatremia (134 mEq/L; reference interval, 140–152 mEq/L) and mild hypochloremia (106 mEq/L; reference interval, 110–121 mEq/L). Venous blood gas analysis identified hypercapnia (50 mm Hg; reference interval, 22–33 mmHg), consistent with a respiratory acidosis (pH = 7.30; reference interval, 7.42–7.50). All chemistry values were obtained from heparinized blood, thus plasma values are reported. Severe leukopenia was identified on CBC with total white blood cell (WBC) count of 1.5 9 10/lL (reference interval, 5.5–13.9 9 10/lL) characterized by neutropenia (0.375 9 10/lL; reference interval, 2.9–12 9 10/lL) and a mild left shift (band neutrophils 0.135 9 10/lL; reference interval, 0–0.45 9 10/lL). A CBC performed several days later had leukocytosis (22.3 9 10/lL), with an inflammatory leukogram (segmented neutrophils 18.286 9 10/lL, band neutrophils 0.223 9 10/lL and monocytosis 1.784 9 10/lL; reference interval, 0.1–1.4 9 10/lL) with slight toxic changes in the neutrophils. Antimicrobial treatment with ampicillin and sulbactam (22 mg/kg IV q8h) and amikacin (15 mg/kg IV q24h 9 5 days) was initiated to treat presumed bronchopneumonia. In addition, intermittent (q4h) nebulization using 0.9% saline with gentle thoracic coupage and aminophylline treatment (5 mg/kg IV q8h) were instituted. Postoperative analgesia was provided with buprenorphine (0.01 mg/kg IV q8h), and both famotidine (1 mg/kg IV q12h) and metoclopramide (1 mg/kg/day IV as constant rate infusion) were administered to decrease the effects of or development of reflux esophagitis. Food was withheld for 24 h, and subsequently frequent (q4h) feedings of canned food were offered after an absence of observed regurgitation. Fluid therapy also was instituted on the first postoperative day using a balanced polyionic crystalloid solution with a sodium concentration of 130 mEq/L, supplemented with 16 mEq KCl/L (for a total of 20 mEq/L of potassium). The initial intravenous fluid This article was published online on 9 April 2015. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected on 30 April 2015. From the Department of Georgia, College of Veterinary Medicine, Athens, GA (Bowles, Brainard, Coleman). Corresponding author: K.D. Bowles, Department of Georgia, College of Veterinary Medicine, 2015 SW 16th Ave., Gainesville, FL 32608; e-mail: [email protected]. Submitted July 14, 2014; Revised January 11, 2015; Accepted February 23, 2015. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes. DOI: 10.1111/jvim.12577 Abbreviations: