Incidence and risk factors for neurological signs after attenuation of single congenital portosystemic shunts in 253 dogs

Objective: To determine the incidence, outcome, and risk factors for postattenuation neurological signs (PANS) and seizures after attenuation of single congenital porto-systemic shunts (CPSS) in dogs. Study design: Retrospective cohort study. Sample population: Dogs (N=253) with single CPSS. Methods: Medical records of dogs treated by surgical attenuation of a single CPSS between February 2000 and July 2015 were reviewed for signalment and preoperative and postoperative clinical outcomes, including the occurrence of PANS. Univariable and multivariable binary logistic regression was used to assess risk factors for PANS and for seizures. Results: Twenty-eight (11.1%) dogs developed PANS, including 12 (4.7%) dogs with seizures. Five (17.9%) dogs with PANS did not survive to discharge. Risk factors for PANS included the presence of hepatic encephalopathy (HE) immediately preoperatively (P5.038, odds ratio [OR] 2.704, CI 1.057-6.922) and increasing age (P<.001, OR 1.476, CI 1.223-1.780). Risk factors for seizures included the presence of HE immediately preoperatively (P=.048, OR 3.538, CI 1.013-12.363) and increasing age (P=.009, OR 1.364, CI 1.082-1.720). No association was found between the location of portosystemic shunts (extrahepatic and intrahepatic) and postoperative PANS (P=.532) or seizures (P=.620). Similarly, preemptive administration of levetiracetam did not influence the risk of PANS (P=.991) or seizures (P=.752). Conclusion: Preoperative HE and older age in dogs with a CPSS increased the odds of developing PANS and seizures in our population. Preemptive administration of levetiracetam did not protect dogs against the development of PANS or seizures.