Weight classification of dogs related to porto-azygous and portocaval shunts. 135 dogs were classified as small (≤ 9 kilo) or medium and large dog breeds (> 9 kilo). The weight classes contained respectively 101, and 34 dogs. Mean weight is based on the standard of the Dutch Kennel Club. Chi-squared test was performed. A significant difference was observed between weight and shunt localization (P = 0.03).