LAUSR

Abstract Background Hepatic supportive diet (HSD), lactulose, and antimicrobials are medical treatments for dogs with congenital extrahepatic portosystemic shunts (cEHPSS). The relative contribution of these treatment components is currently unknown. Objectives To determine which treatment combinations are most efficacious in pre‐surgical control of clinical signs of cEHPSS in dogs. Animals Thirty‐six dogs with untreated cEHPSS. Methods Three‐arm randomized clinical trial. At inclusion (T0), dogs were divided into 3 groups: HSD (n = 12), HSD + lactulose (n = 12), or HSD + metronidazole (n = 12) and received the randomized treatment for 4 weeks (T1) followed by combined treatment of HSD + lactulose + metronidazole for 2 weeks or until cEHPSS attenuation (T2). Clinical score as well as fasting ammonia (FA) and C‐reactive protein (CRP) concentrations were compared among groups and time points. Results Thirty‐four dogs were evaluated. Thirty‐four dogs reached T1 and 29 dogs T2. At T1, clinical scores decreased in the HSD + lactulose (n = 11; P = .001), but not in the HSD (n = 8; P = .96) and HSD + metronidazole (n = 10; P = .06) groups. Adding metronidazole to HSD + lactulose (n = 11) did not result in further clinical score improvement (T2; P = 1.000). Moderate and weak correlation between clinical score and FA and clinical score and CRP was present (ρ = .35, P < .001; ρ = .27, P = .01, respectively) with FA decreasing over time on medical treatment (P = .001). Conclusions and Clinical Importance Combined HSD + lactulose seems sufficient for pre‐surgical cEHPSS stabilization unlike sole HSD or HSD + metronidazole. Medical treatment of cEHPSS clinical signs decreases FA.