A study of the prognostic usefulness of blood leukocyte changes in canine parvoviral enteritis

Canine parvoviral enteritis is an economically important disease in South Africa and \nglobally. Although treatment of dogs with parvoviral enteritis is often successful, many \ndogs die of complications related to septicaemia or are euthanized because of \nanticipated high costs. More effective prediction of the outcome of this disease will \nhave an economic impact if a prognosis can be determined early in the course of the \ndisease. Although leukocyte responses seldom are pathognomonic for a specific disease, \nthey can provide clinical information to establish a fairly reliable prognosis. \nA prospective study was performed on 62 puppies presented to the OVAH with typical \nclinical signs of canine parvoviral enteritis that subsequently was confirmed on electron \nmicroscopy. Full haematology was performed at admission as well as every consecutive \nday until death or discharge. Of the 11 puppies that died (18%), nine died due to \ncomplications of the disease and two were euthanized due to financial restrictions and a \npoor prognosis. The puppies that died due to the disease died within the first three days \nof hospitalization. All the puppies that died were sent for a full post mortem \nexamination and histopathological evaluation. \nStatistical analysis of the data showed that there was a definite difference between the \npuppies that died and those that survived in several of the leukocyte parameters. These \nparameters included the total leukocyte, lymphocyte, monocyte and eosinophil counts. \nIn none of the puppies that died from the disease did the total leukocyte count rise \nabove 2.0 × 10 \n9 \n/l (normal reference range: 6.0-15.0 × 10 \n9 \n/l). In the puppies that \nsurvived, the total leukocyte count started rising within 24 – 48 hours after admission \nand often resulted in a rebound leukocytosis. The puppies that died did not develop \nlymphocytosis to indicate an immune response, whereas the surviving puppies \ndeveloped lymphocytosis within 24 – 48 hours after admission. The puppies that died \nalso did not develop monocytosis and remained severely eosinopaenic during the course \nUniversity of Pretoria etd – Goddard, A (2006) \nxii \nof the disease. Evidence of impaired leukocyte production was found on histopathology. \nMost of the puppies that died from the disease showed marked to severe thymic and \nlymphoid atrophy and marked to severe bone marrow hypocellularity. \nThese results show that a reliable prognosis can be obtained at 24 and 48 hours after \nadmission by evaluation of the leukocytes, specifically the total leukocyte, lymphocyte, \nmonocyte and eosinophil counts.