Surgical attenuation of spontaneous congenital portosystemic shunts in dogs resolves hepatic encephalopathy but not hypermanganesemia.

Hypermanganesemia is commonly recognized in human patients with hepatic insufficiency and portosystemic shunting. Since manganese is neurotoxic, increases in brain manganese concentrations have been implicated in the development of hepatic encephalopathy although a direct causative role has yet to be demonstrated. Evaluate manganese concentrations in dogs with a naturally occurring congenital shunt before and after attenuation as well as longitudinally following the changes in hepatic encephalopathy grade. Our study demonstrated that attenuation of the shunt resolved encephalopathy, significantly reduced postprandial bile acids, yet a hypermanganasemic state persisted. This study demonstrates that resolution of hepatic encephalopathy can occur without the correction of hypermanganesemia, indicating that increased manganese concentrations alone do not play a causative role in encephalopathy. Our study further demonstrates the value of the canine congenital portosystemic shunt as a naturally occurring spontaneous model of human hepatic encephalopathy.

Closed suction drainage for treatment of septic peritonitis of confirmed gastrointestinal origin in 20 dogs.

OBJECTIVE: To determine survival rate in dogs with septic peritonitis of confirmed gastrointestinal origin treated with closed suction drainage. STUDY DESIGN: Retrospective case series. ANIMALS: Dogs (n = 20) with septic peritonitis. METHODS: Medical records (2007-2010) of dogs with septic peritonitis of confirmed gastrointestinal origin treated by closed suction drainage were reviewed. Information on signalment, clinicopathologic abnormalities, underlying cause, surgical procedure performed, postoperative management, complications, and outcome was obtained. RESULTS: Dehiscence of a previous anastomosis was the most common source of contamination (80%). Drains remained in place, collecting fluid produced within the abdomen, for a median of 6 days (range, 2-11 days). Eighteen dogs received nutritional support, and 14 received plasma transfusions. Seventeen dogs (85%) survived to discharge. CONCLUSIONS: Closed suction drainage together with resolution of the underlying cause of peritonitis and appropriate postoperative management is an effective technique for treatment of septic peritonitis of confirmed gastrointestinal origin in dogs.

Intra-operative hyperthermia in a cat with a fatal outcome.

HISTORY: A four year old male neutered Domestic Short Hair cat presented for general anaesthesia for hind limb orthopaedic surgery. The cat had been anaesthetized four days previously with propofol and isoflurane and made an uneventful recovery. PHYSICAL EXAMINATION AND MANAGEMENT: On pre-anaesthetic examination the cat had a temperature of 38.9 °C and was otherwise healthy. After a premedication of acepromazine and pethidine, anaesthesia was induced with thiopental and maintained with isoflurane in oxygen 50% and nitrous oxide 50%. Increases in heart rate, respiratory rate, end tidal carbon dioxide tension and temperature were observed, occurring sequentially, from 110 to 175 minutes after anaesthetic induction. Despite ceasing all warming measures and attempting to cool the patient, body temperature continued to rapidly rise, reaching 42.5 °C and limb rigidity was observed. Isoflurane administration was stopped and esmolol was administered. Cardiac arrest occurred. Cardio-pulmonary cerebral resuscitation was commenced and a lateral thoracotomy was performed to allow cardiac compressions and internal defibrillation. Atropine, adrenaline, glucose and dopamine were administered and cold saline was instilled into the thoracic cavity. FOLLOW-UP: Resuscitation was unsuccessful and the cat died. CONCLUSIONS: A presumptive diagnosis of malignant hyperthermia was made. Malignant hyperthermia should be considered, even if prior exposure to volatile inhalational anaesthesia was uneventful, and prompt and aggressive therapy instituted.

Caudal mediastinal paraesophageal abscesses in 7 dogs.

OBJECTIVE: To report clinical, imaging, and surgical findings associated with caudal mediastinal paraesophageal abscesses (CMPA) in dogs and outcome after surgical treatment. STUDY DESIGN: Case series. ANIMALS: Dogs (n = 7) with CMPA. METHODS: Medical records (April 2005-January 2010) were reviewed for dogs with CMPA treated surgically. Retrieved data were signalment, history, clinical findings, diagnostic investigations, surgical findings, surgical procedures performed, and postoperative recovery. Long-term follow-up information was obtained by telephone questionnaire of owners and referring veterinarians. RESULTS: Median sternotomy (5 dogs) or lateral thoracotomy (2 dogs) was used for access to CMPA, which were drained and partially debrided surgically. In 5 dogs, omentalization of the abscess cavity was performed through a diaphragmatic incision. Foreign material was not identified within any abscess. All dogs were discharged from the hospital and had full recovery. CONCLUSIONS: CMPA should be suspected when there is regurgitation and pyrexia associated with a mass or enlargement in the caudal mediastinum. CMPA appears to have a good prognosis after aggressive surgical therapy.

Minimally invasive inguinal approach for tube cystostomy.

OBJECTIVE: To report a technique for tube cystostomy placement via a minimally invasive inguinal approach and outcome in 9 dogs and 6 cats with urinary tract obstruction or detrusor atony. STUDY DESIGN: Case series. ANIMALS: Dogs (n=9) and cats (6). METHODS: Medical records (January 2004-January 2008) of dogs and cats that had tube cystostomy via an inguinal approach were reviewed. Retrieved data included signalment, diagnosis, surgical technique, and complications. Access to the bladder was through a muscle splitting approach in the inguinal region with the cystostomy tube placed through a skin incision made several centimeters proximal to this incision and secured in the bladder by a purse string suture. Cystopexy during closure of the muscle layers ensured secure closure and minimized the likelihood of uroabdomen if tube dislodgment occurred. RESULTS: Cystostomy tubes were placed in 5 cats as an emergency procedure for treatment of acute urinary tract obstruction or urethral rupture, and as an elective procedure in 9 dogs and 1 cat. No complications occurred during cystostomy tube placement. Postprocedural complications were minor (peristomal irritation in 2 dogs with latex catheters, catheter laceration, premature removal) and only occurred when tubes were retained for >4 weeks. Urinary tract infection at catheter removal in 6 dogs resolved with antibiotic administration. CONCLUSIONS: An inguinal approach for cystostomy tube placement facilitated rapid catheter placement into the bladder with minimal soft tissue dissection. Cystopexy during abdominal wall closure provided peritoneal protection should premature dislodgement of the cystostomy tube occur. CLINICAL RELEVANCE: An inguinal approach should be considered for rapid tube cystostomy particularly in metabolically compromised animals.

Comparison of visual analog and numeric scoring scales for assessing intraoperative mesenteric portovenography.

A visual analog scale and a numeric scoring scale were designed for the assessment of dynamic intraoperative mesenteric portovenography in the dog and cat. Two independent observers evaluated both scoring scales for reproducibility (differences between observers) and repeatability (within-observer differences) in the assessment of 60 trial portovenograms. Agreement (interchangeability) of both scales was evaluated by comparing the scores obtained in the assessment of 200 portovenograms obtained from 100 dogs and cats. There was no statistical difference between the two observers when scoring the same portovenogram for either the visual analog scale (p = .730, reproducibility coefficient = 17.85 units) or the numeric scoring scale (scores identical, reproducibility coefficient = 0). There was no statistical difference, for either of the observers, when the same portovenogram was assessed on two separate occasions using the visual analog scale (observer 1, p = .35, repeatability coefficient = 17.93 units; observer 2, p = .42, repeatability coefficient = 8.27 units) or the numeric scoring scale (scores given by both observers were identical, repeatability coefficient = 0 for both observers). The results of comparison between the visual analog scale and numeric scoring scale confirmed that the two scoring systems were not directly interchangeable. Although both scoring systems demonstrated good reproducibility and repeatability, the numeric scoring scale possessed a number of inherent deficiencies that suggested it was not the method of choice for the assessment of the subjective data obtained from dynamic intraoperative mesenteric portovenography.

Use of intraoperative mesenteric portovenography in congenital portosystemic shunt surgery.

A retrospective study of the use of intraoperative mesenteric portovenography (IOMP) in the surgical management of congenital portosystemic shunts in 100 dogs and cats was performed. Each portovenogram was scored using a subjective visual analogue scale (VAS) and was assessed for the presence of portal atresia or hypoplasia. VAS scores and portal hypoplasia assessments were obtained for portovenogram images obtained for each animal both before shunt manipulation (preligation) and following the temporary, complete ligation of the vessel (postligation). In each patient, surgical records were reviewed to ascertain the degree of shunt attenuation that was achieved at surgery. Hepatic portal vasculature was significantly different on postligation compared with preligation IOMP. Sixty-two percent of animals had apparent portal hypoplasia or atresia on their preligation IOMP. The majority of these (81%) had an improvement in portal vasculature on postligation IOMP. It was concluded that both preligation and postligation IOMP provided valuable information regarding the morphology of congenital portosystemic shunts. An accurate assessment of an animal's portal vasculature could only be made following the interpretation of a postligation portovenogram, and these findings significantly influenced the surgical management of the patient. Although individuals with high postligation VAS scores were more likely to achieve full shunt attenuation at surgery, there was no quantifiable relationship between IOMP findings and the degree of shunt attenuation achieved.