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

Objective

To describe the incidence, outcome and identify possible risk factors for Post Attenuation Neurological Signs (PANS) and seizures in dogs that have undergone attenuation of a single congenital portosystemic shunt (CPSS).

Study Design

Retrospectivecohort study.

Sample Population

Dogs (n=253) with a single, congenital portosystemic shunt.

Methods

Medical records of dogs with a single CPSS surgically attenuated between February 2000 and July 2015 were reviewed for signalment, pre and post-operative clinical data, 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 twelve (4.7%) dogs that seizured. Five (17.9%) dogs with PANS did not survive to discharge.

The risk factors for PANS included the presence of HE immediately pre-operatively  (p=0.038, odds ratio 2.704, confidence interval 1.057-6.922) and increasing age (p<0.001, odds ratio 1.476, confidence interval 1.223-1.780). The risk factors for seizures included the presence of HE immediately pre-operatively (p=0.048, odds ratio 3.538, confidence interval 1.013-12.363) and increasing age (p=0.009, odds ratio 1.364, confidence interval 1.082-1.720).

Conclusions

Pre-operative HE and older age in dogs with a CPSS increase the odds of developing PANS and seizures. Neither extrahepatic or intrahepatic shunts were at an increased risk of developing PANS or seizures. Prophylactic levitiracetam was not protective for the development of PANS or seizures.

Clinical Significance

Our findings would suggest that surgical attenuation of a single CPSS should not be excessively delayed and that clinical signs of HE should be stabilized before surgery.