Evaluation of two unilateral laryngoplasty techniques and their effect on arytenoid cartilage abduction in cats.

OBJECTIVES: The aim of this study was to evaluate two unilateral laryngoplasty (arytenoid lateralisation) techniques for use in the surgical management of laryngeal paralysis in cats. METHODS: Left cricoarytenoid abduction (lateralisation) was performed in 20 ex vivo cat larynges; 10 following complete cricoarytenoid disarticulation (group LAA-dis) and 10 following no cricoarytenoid disarticulation (group LAA-nodis). For both groups, left arytenoid abduction (LAA) was measured in the resting and postoperative larynges using image analysis software. Measurements were evaluated using the Mann-Whitney U-test. For both groups, dorsal images of the postoperative larynges were assessed visually for evidence of epiglottic coverage of the entrance to the larynx. RESULTS: The mean percentage increase in LAA was 311.5% and 199.4% (P <0.006) for group LAA-dis (complete cricoarytenoid disarticulation) and group LAA-nodis (no cricoarytenoid disarticulation), respectively. In both groups, there was no evidence of a lack of epiglottic coverage of the entrance of the larynx for any of the postoperative larynges. CONCLUSIONS AND RELEVANCE: Placement of a single, tensioned suture between the muscular process of the left arytenoid cartilage and the caudolateral aspect of the ipsilateral cricoid cartilage (unilateral cricoarytenoid lateralisation) resulted in abduction of the left arytenoid cartilage and a corresponding increase in the area of the rima glottidis on the operated side. The clinical significance of the difference in outcome between left cricoarytenoid abduction following complete cricoarytenoid disarticulation and abduction following no cricoarytenoid disarticulation remains unclear, and both might be considered appropriate for the surgical management of laryngeal paralysis in the cat.

Postattenuation neurologic signs after surgical attenuation of congenital portosystemic shunts in dogs: A review.

The development of postattenuation neurologic signs (PANS) is a poorly understood and potentially devastating complication after surgical attenuation of congenital portosystemic shunts in dogs. Postattenuation neurologic signs include seizures but also more subtle neurologic signs such as depression, behavioral changes, tremors, and twitching. They most commonly occur within 7 days postoperatively and are typically unrelated to hyperammonemia, hypoglycemia, or electrolyte disturbances. This narrative review summarizes the findings of 50 publications from 1988-2020 that report occurrence of PANS. While most published reports included only dogs affected by postattenuation seizures (PAS), others included dogs with any form of PANS. Overall, PANS (including PAS) affected 1.6%-27.3% of dogs, whereas incidence of PAS ranged from 0%-18.2%. The etiology of PANS remains unknown; however, several theories have been proposed. Risk factors include preoperative hepatic encephalopathy, increasing age, and possibly certain breeds and extrahepatic shunt morphology. There is increasing evidence that prophylactic antiepileptic drugs do not prevent PANS. Treatment is centered around controlling neurologic signs with antiepileptic drugs and providing supportive intensive care. The 30-day survival rate in studies that included a minimum of four dogs affected by PANS was 0%-100% (median, 50.0%) and 0%-75.0% (median, 37.5%) for those with PAS. Mortality associated with PANS was typically related to occurrence of generalized seizure activity. Prognostic factors positively associated with short-term survival included having a history of preoperative seizures and development of focal seizures only. If affected dogs survived to discharge, survival for several years was possible, and the majority of neurologic signs manifested as part of the phenomenon of PANS appeared to resolve.

Prognostic factors for short-term survival of dogs that experience postattenuation seizures after surgical correction of single congenital extrahepatic portosystemic shunts: 93 cases (2005-2018).

OBJECTIVE: To identify prognostic factors for short-term survival of dogs that experience seizures within 7 days after surgical correction of single congenital extrahepatic portosystemic shunts (cEHPSS). STUDY DESIGN: Multi-institutional retrospective study. SAMPLE POPULATION: Ninety-three client-owned dogs. METHODS: Medical records at 14 veterinary institutions were reviewed to identify dogs that underwent surgical attenuation of a single cEHPSS from January 1, 2005 through February 28, 2018 and experienced postattenuation seizures (PAS) within 7 days postoperatively. Logistic regression analysis was performed to identify factors associated with 1-month survival. Factors investigated included participating institution, signalment, shunt morphology, concurrent/historical conditions, presence of preoperative neurologic signs, presence of preoperative seizures, aspects of preoperative medical management, surgical details including method and degree of shunt attenuation, type of PAS (focal only or generalized ± focal), drugs administered as part of the treatment of PAS, and development of complications during treatment of PAS. RESULTS: Thirty (32.3%) dogs survived to 30 days. Seventy-six (81.7%) dogs experienced generalized PAS. Factors positively associated with short-term survival included having a history of preoperative seizures (P = .004) and development of focal PAS only (P = .0003). Most nonsurvivors were humanely euthanized because of uncontrolled or recurrent seizures. CONCLUSION: Dogs that experienced PAS that had a history of preoperative seizures and those that experienced focal PAS only had significantly improved short-term survival. CLINICAL SIGNIFICANCE: The results of this study provide information that will help in the counseling of owners who seek treatment for PAS after surgical correction of cEHPSS. © 2020 The American College of Veterinary Surgeons.

Effect of prophylactic treatment with levetiracetam on the incidence of postattenuation seizures in dogs undergoing surgical management of single congenital extrahepatic portosystemic shunts.

OBJECTIVE: To report the incidence of postattenuation seizures (PAS) in dogs that underwent single congenital extrahepatic portosystemic shunt (cEHPSS) attenuation and to compare incidence of PAS in dogs that either did or did not receive prophylactic treatment with levetiracetam (LEV). STUDY DESIGN: Multi-institutional retrospective study. POPULATION: Nine hundred forty dogs. METHODS: Medical records were reviewed to identify dogs that underwent surgical attenuation of a single cEHPSS from January 2005 through July 2017 and developed PAS within 7 days postoperatively. Dogs were divided into 3 groups: no LEV (LEV-); LEV at ≥15 mg/kg every 8 hours for ≥24 hours preoperatively or a 60 mg/kg intravenous loading dose perioperatively, followed by ≥15 mg/kg every 8 hours postoperatively (LEV1); and LEV at <15 mg/kg every 8 hours, for <24 hours preoperatively, or continued at <15 mg/kg every 8 hours postoperatively (LEV2). RESULTS: Seventy-five (8.0%) dogs developed PAS. Incidence of PAS was 35 of 523 (6.7%), 21 of 188 (11.2%), and 19 of 228 (8.3%) in groups LEV-, LEV1, and LEV2, respectively. This difference was not statistically significant (P = .14). No differences between groups of dogs that seized with respect to investigated variables were identified. CONCLUSION: The overall incidence of PAS was low (8%). Prophylactic treatment with LEV according to the protocols that were investigated in our study was not associated with a reduced incidence of PAS. CLINICAL SIGNIFICANCE: Prophylactic treatment with LEV does not afford protection against development of PAS. Surgically treated dogs should continue to be monitored closely during the first 7 days postoperatively for seizures.

Congenital Extrahepatic Abdominal Arteriovenous Fistula and Apparent Patent Ductus Venosus in a Dog.

A 3 mo old male German shepherd dog presented with a 2 wk history of diarrhea with possible melena followed by inappetence and progressive abdominal distension. Clinical findings, serum biochemical analysis, and abdominal ultrasound were highly suggestive of an extrahepatic abdominal arteriovenous fistula and concurrent patent ductus venosus, which were confirmed during an abdominal exploratory surgery. Renal biopsies taken at the time of surgery confirmed a chronic glomerulopathy. The dog made a good initial recovery from the procedure but was euthanatized 6 wk postoperatively for medically unresponsive renal disease.

Successful surgical treatment of a suspected iatrogenic arytenoid cartilage fracture in a dog.

A 3-year-old, intact female golden retriever was presented with a sudden onset of inspiratory obstructive dyspnea following general anesthesia to perform a mastectomy. The cuneiform process of the left arytenoid cartilage was found to be extremely mobile on laryngeal examination. Fracture of the cuneiform process of the left arytenoid cartilage was diagnosed. A combined cricoarytenoid and thyroarytenoid caudolateralization procedure was performed on the left side, and no further dyspnea was observed during a follow-up period of 7 months. Fracture of the cuneiform process of the arytenoid cartilage has not been previously reported in dogs. The condition may respond favorably to cricoarytenoid and thyroarytenoid caudolateralization surgery.

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.

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.