Plasma granulocyte colony-stimulating factor concentrations in neutropenic, parvoviral enteritis-infected puppies

We evaluated the temporal relationship between neutrophil numbers and plasm a granulocyte colony-stimulating factor (G-CSF) concentrations in dogs infe cted with canine parvovirus, a common infectious cause of neutropenia. G-CS F is produced in response to neutropenia, infection, or inflammation, and r esults in the production and release of neutrophils from the bone marrow. A dequate numbers of functional neutrophils are necessary for protection from infection, and the timely production of G-CSF is a crucial response to cer tain diseases. The relationship between peripheral neutrophil numbers and p lasma G-CSF concentrations during the course of an infectious disease chara cterized by neutropenia has not been described previously in dogs. Eight mi xed-breed puppies were given an oronasal challenge with canine parvovirus, and peripheral neutrophil numbers as well as plasma G-CSF concentrations we re measured daily. G-CSF was not detectable in plasma of any dog before the onset of neutropenia, but G-CSF became detectable just after the onset of neutropenia in the 7 dogs that developed clinical illness. Neutropenia pers isted or worsened for at least 2 days after plasma G-CSF became detectable in all 7 dogs, Neutrophil nadir, the highest plasma G-CSF concentrations, a nd the most severe clinical illness occurred concurrently in most dogs. Alt hough 1 dog died while still neutropenic, plasma G CSF concentrations decli ned before resolution of neutropenia in the other 6 dogs, and were again be low the limits of detection in 5 of the 6 dogs at the time of resolution.