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

Abstract

Canine parvoviral enteritis is an economically important disease in South Africa and globally. Although treatment of dogs with parvoviral enteritis is often successful, many dogs die of complications related to septicaemia or are euthanized because of anticipated high costs. More effective prediction of the outcome of this disease will have an economic impact if a prognosis can be determined early in the course of the disease. Although leukocyte responses seldom are pathognomonic for a specific disease, they can provide clinical information to establish a fairly reliable prognosis. A prospective study was performed on 62 puppies presented to the OVAH with typical clinical signs of canine parvoviral enteritis that subsequently was confirmed on electron microscopy. Full haematology was performed at admission as well as every consecutive day until death or discharge. Of the 11 puppies that died (18%), nine died due to complications of the disease and two were euthanized due to financial restrictions and a poor prognosis. The puppies that died due to the disease died within the first three days of hospitalization. All the puppies that died were sent for a full post mortem examination and histopathological evaluation. Statistical analysis of the data showed that there was a definite difference between the puppies that died and those that survived in several of the leukocyte parameters. These parameters included the total leukocyte, lymphocyte, monocyte and eosinophil counts. In none of the puppies that died from the disease did the total leukocyte count rise above 2.0 × 10 9 /l (normal reference range: 6.0-15.0 × 10 9 /l). In the puppies that survived, the total leukocyte count started rising within 24 – 48 hours after admission and often resulted in a rebound leukocytosis. The puppies that died did not develop lymphocytosis to indicate an immune response, whereas the surviving puppies developed lymphocytosis within 24 – 48 hours after admission. The puppies that died also did not develop monocytosis and remained severely eosinopaenic during the course University of Pretoria etd – Goddard, A (2006) xii of the disease. Evidence of impaired leukocyte production was found on histopathology. Most of the puppies that died from the disease showed marked to severe thymic and lymphoid atrophy and marked to severe bone marrow hypocellularity. These results show that a reliable prognosis can be obtained at 24 and 48 hours after admission by evaluation of the leukocytes, specifically the total leukocyte, lymphocyte, monocyte and eosinophil counts.