Case of the Month

Peritonitis: Cause or Symptom

History: A 3-year old neutered male Dachshund was presented to the emergency service on referral from his regular veterinarian for protracted vomiting and suspicion of gastrointestinal obstruction. The dog had no known history of dietary indiscretion, but had been vomiting multiple times for two days prior to presentation here and had been inappetent. His referring veterinarian had performed blood work which showed presumptive pre-renal azotemia (BUN 51 mg/dL (7-27)) and hemoconcentration (HCT 63%). A urine specific gravity was not checked at this time. There was also a mild elevation of the alkaline phosphatase (ALP) at 240 U/L (23-212) and an elevation of the total bilirubin (T. bili) of 2.5 mg/dL (0.0-0.9). Radiographs taken by the referring veterinarian were suspicious for gastrointestinal obstruction.

Physical Exam: On presentation, the dog was depressed, but alert and responsive. He was 8-10% dehydrated, and had a body temperature of 98.9 degrees Fahrenheit, a heart rate of 180 beats per minute, and a respiratory rate of 30 breaths per minute. Abdominal palpation revealed a tubular mid-abdominal mass effect. The patient’s blood pressure on presentation was 70 mmHg. An intravenous catheter was placed, a dose of Hydromorphone was given, and a bolus of IV LRS was given rapidly over 15 minutes. Following fluid resuscitation with crystalloids, the patient’s blood pressure improved to 105 mmHg.

Diagnostics and Therapy: Shortly after volume resuscitation, the patient was taken for an exploratory laparotomy. The explore revealed foreign material extending from the proximal to mid-jejunum with some plication. An enterotomy was performed in the proximal jejunum to remove some of the foreign material. 10-15 cm of the mid-jejunum needed to be removed via resection and anastomosis due to compromise of the bowel. The proximal remaining portion was bruised, but had good pulses and motility so was left in place. The patient maintained normal heart rate, body temperature, and blood pressures during the entire anesthetic procedure.

Intravenous Cefazolin (22 mg/kg) was given perioperatively and continued post-operatively. Following surgery a jugular sampling catheter was placed, and a venous blood gas revealed hypokalemia of 2.98 Mm. The patient’s postoperative PCV was 58%, with total solids of 4.4 g/dL and a blood glucose of 80 mg/dL. A morphinelidocaine-ketamine continuous infusion was started for post-operative pain control (morphine at 4 mcg/kg/min, lidocaine at 25 mcg/kg/min, and ketamine at 10 mcg/kg/min). Ruedi did well overnight, maintaining adequate blood pressures, normal vital signs, and resting comfortably. Follow-up blood work performed the following morning, however, revealed hypoglycemia (28 mg/dL on hand-held glucometer). The patient was given a bolus of 1 mL/kg of 50% dextrose, diluted over 5 minutes, and the crystalloids were supplemented with 2.5% dextrose. Repeat blood chemistry revealed hypoalbuminemia of 0.5 g/dL (2.5-4.4). We also found that the patient’s ALP remained elevated at 180 U/L (20-150), and that the total bilirubin was increased at 1.0 mg/dL (0.1-0.6). The azotemia from the previous day had resolved. The patient was also mildly coagulopathic, with a PT of 19 sec (12-17) and a PTT of 171 sec (71-102). Due to the profound hypoalbuminemia, the patient was started on colloid therapy with hetastarch (HES) at approximately 1 ml/kg/hr. Because of concerns of predisposition to thromboembolic disease due to the hypoalbuminemia, the patient was started on low molecular weight Heparin at 100 IU/kg SQ BID. Over the next 2 hours, the patient’s blood pressure fell from 100 mmHg to 40 mmHg. He received a 5 mL/kg bolus of HES and the MLK CRI was discontinued in case the morphine or lidocaine was contributing to the hypotension. Following these actions, the patient’s blood pressure improved to 60 mmHg. He received an additional bolus of HES, at which point his blood pressure improved to 110 mmHg.

The patient’s HES CRI rate was increased at this point to 1.5 ml/kg/hr. Metoclopramide at 1.5 mg/kg/day was added later in the afternoon after the patient had an episode of regurgitation. For the rest of the day, the patient remained normotensive and maintained a normal blood glucose level (on supplementation). Repeat clotting times later during the day showed improvement of the coagulopathy (values not available).

The next day (day 2 post-op) a repeat chemistry screen showed persistent hypoalbuminemia at 0.5 g/dL, elevated ALP at 389 U/L, and an elevated total bilirubin of 2.8 mg/dL. Differential diagnoses for the increasing ALP and total bilirubin included sepsis, cholestasis, or pancreatitis. Due to concerns about possible sepsis, the patient was switched from Cefazolin to Ampicillin for better coverage of gram negative and anaerobic microorganisms. The patient maintained a normal blood pressure throughout the day on maintenance rates of crystalloids and 1 ml/kg/hour of HES. He had no vomiting, but continued to refuse food.

On day 3 post-op, an abdominal ultrasound was performed due to concerns about the patient’s continued abdominal pain and anorexia, as well as the clinical laboratory findings from the previous day. Ultrasound revealed 2 abnormal segments of bowel; one loop was fluid-filled with thin poorly defined walls, and another (thought likely the segment where the resection and anastomosis had been performed) looked thickened. There was very echogenic fat and mesentery in the cranial abdomen, which concerned the radiologist beacause it was more than she would expect at 2-3 days post-operative. The small bowel was diffusely immotile. Our chief concerns were possible dehiscence of the resection and anastomosis site, or possibly focal pancreatitis. At this point, we discussed the possibility of a repeated exploratory laparotomy with the owner, who elected to pursue further medical management at this time. We continued treatments as above, and gave a plasma transfusion as well (to help with oncotic support, as well as to provide clotting factors and albumin). Later in the day, the patient started eating small amounts.

By the next day, Ruedi was consistently eating when fed by his owner. He remained afebrile, and was maintaining a normal blood pressure. Recheck blood work showed that his albumin had increased to 1.4 g/dL, his ALP was about the same at 344 U/L, and his total bilirubin had decreased to 1.1 mg/dL. Repeat clotting times revealed a PT of 15 sec and a PTT of 97 sec. By this point, the patient had become quite fractious in the hospital (his usual disposition, per the owner). Due to this and his clinical improvement, he was discharged to the care of his owner at this time. He was discharged on amoxicillin 20 mg/kg BID, Metronidazole 10 mg/kg BID, Tramadol 2 mg/kg q 8-12h, and Metoclopramide 0.35 mg/kg q 8-12h. He went on to make a full recovery.

Discussion: Peritonitis is an important cause of abdominal pain in dogs. In this patient, it was difficult to ascertain whether the peritonitis was secondary to dehiscence and sepsis, or due to pancreatitis and/or postoperative inflammation. Both could potentially cause the signs that we saw including post-operative hypoalbuminemia, hypoglycemia, and hyperbilirubinemia and elevated ALP, in addition to the hypotension and mild coagulopathy experienced by this patient. Close monitoring and aggressive medical therapy is important in these patients.

At VESCONE, our staff and doctors are ready to provide the needed intensive monitoring as well as the medical and surgical therapies required to save patients like Ruedi. Please call us if you need assistance with any of your patients, including overnight monitoring of your post-op patients or if you need Hetastarch or other blood products. We want to help you in any way we can.

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