Diseases associated with Monocytosis in Swedish dogs - a retrospective study. The purpuse of this retrospective study is to determine which diseases are associated with pronounced Monocytosis in Swedish dogs. Records of 153 dogs with Monocytosis were evaluated. The most common cause was infectious diseases (49%) of which pyometra was seen in 23% of the cases, cystitis and fever of unknown origin each in 13% and gastroenteritis in 12%. Cortison treatment was the second most common cause with 29%. A sixth of the dogs had non inflammatory diseases such as neoplasia, renal- and heartfailure.