Evaluation of serum C-reactive protein levels as a predictor of outcome in puppies infected with parvovirus

Abstract

Canine Parvovirus remains a leading cause of enteritis in dogs in South Africa and many other countries despite the wide availability of effective vaccines. The virus does not affect all dogs equally and the course of the disease depends on the age, immune status and breed of the puppies as well as the viral dose, route of exposure and the virulence of the strain. Although aggressive supportive treatment can be successful, the treatment and convalescent periods may be prolonged and consequently expensive and the mortality rate relatively high, causing many clients to forego treatment and elect for euthanasia of their pet. Acute phase proteins (APP) are proteins that change in concentration by at least 25% in animals subjected to external or internal inflammatory challenges, such as infection, inflammation or surgical trauma. Increased concentrations are associated with poor outcome in certain diseases. C-reactive protein (CRP) is the most sensitive APP in dogs. Its normal physiological concentration is low but increases rapidly with inflammation or tissue destruction. Due to the fact that CRP has a relatively short half life in serum (6-8 hours) and a high response in diseased animals, it can be used as a valid measure of a systemic response to an initiating stimulus at the time of blood sampling. By taking serial measurements, objective information about the extent of the ongoing lesions in the patient can be obtained and therefore may be used as a prognostic indicator. The objective of this prospective observational study was to evaluate the association of serum CRP concentrations in puppies suffering from canine parvoviral enteritis with morbidity and mortality, and to determine the usefulness of CRP to predict duration of hospitalisation time. Seventy-nine client owned puppies naturally infected with canine parvovirus were included. Parvovirus infection was diagnosed on electron microscopic examination of faeces from the puppies. CRP was measured using an automated human C-Reactive Protein Turbidimetric Immunoassay (TIA), which has been validated for use in dogs. Serum CRP measurements were performed at admission, twice daily for the first 48 hours, then once daily until death or discharge. There was a positive association between odds of mortality and CRP concentration on admission, as well as 12 and 24 hours after admission (P=0.04,P=0.005 and P=0.003, respectively). Survival time was negatively associated with CRP concentration at 12 and 24 hours after admission (P=0.002and P=0.001, respectively). Among the survivors, length of hospitalisation was positively associated with CRP concentration at 12, 24 and 36 hours after admission (P=0.012, P=0.001 and P=0.002, respectively). Utility for CRP concentration to correctly differentiate between survivors and non-survivors at 24 hours after admission had a sensitivity and specificity of 78.7% and 86.7% respectively. Although serum CRP concentration is associated with outcome in puppies infected with canine parvovirus, when used alone it did not prove to be a good predictor of survival.