Experimental evaluation of four methods of progressive venous attenuation in dogs

Objective-To determine the most effective and reliable method for progressi ve attenuation of single extrahepatic portosystemic shunts in dogs. Study Design-The effects of the four treatments on femoral vein diameter an d histology were compared with controls. Animals-Fourteen healthy adult dogs. Methods-Twenty-eight canine femoral veins were subjected to sham surgery (4 ), partial attenuation using silk (5), cellophane banding (6), ameroid cons trictor implantation (5), and intravascular thrombogenic coils (8). Changes in vein diameter were evaluated at weekly intervals using venography. Afte r 6 weeks, the dogs were humanely euthanatized, and histopathology was perf ormed on the femoral veins. Results-Only cellophane and ameroid constrictors produced progressive and p ermanent Vein attenuation. Ameroid constrictors produced complete occlusion within 14 days in four of five veins and by 21 days in the fifth vein. Cel lophane banding produced slow progressive (but not complete) attenuation in five of six veins. Complete occlusion was demonstrated in four of eight ve ins after thrombogenic coil implantation; however, recanalization occurred in all but one dog. Perivascular silk did not produce significant progressi ve attenuation. Conclusions-Ameroid constrictors produced rapid occlusion of femoral veins. Cellophane banding resulted in slower attenuation. Thrombogenic coils prod uced attenuation, bur this was not sustained in many cases. Silk did not pr omote ongoing attenuation. Clinical Relevance-Both ameroid constrictor implantation and cellophane ban ding show promise for progressive attenuation of single extrahepatic portos ystemic shunts in dogs. Because rapid occlusion was seen with ameroid const rictors, however, cellophane banding maybe a safer technique in animals wit h increased hepatic vascular resistance. Further evaluation of both treatme nts in clinical cases is warranted. (C)Copyright 1999 by The American Colle ge of Veterinary Surgeons.