Evaluation of selected inflammatory markers in cats with feline infectious peritonitis before and after therapy

Feline infectious peritonitis (FIP), once considered fatal disease with a mortality rate approaching 100%, has experienced a new therapeutic breakthrough in recent years. The aim of our study was to evaluate selected clinicopathological parameters before and after GS- 445124-based treatment of FIP in cats, which could serve as potential candidates for predicting treatment success and monitoring treatment progress.

Pre-treatment haematological parameters in 32 treated cats showed moderate leukocytosis, neutrophilia, lymphopenia and anaemia, which normalised post-treatment. Pre-treatment values of haemogram-derived inflammatory markers (ratio of neutrophils to lymphocytes, platelets to lymphocytes, lymphocytes to monocytes and the systemic immune-inflammatory index) differed significantly from those in the healthy cats and between patients with effusive and non-effusive disease (p < 0.05). Post-treatment, only the ratio of lymphocytes to monocytes remained higher; the other three markers were comparable to the control group. The biochemical results showed characteristic abnormalities (e.g. hyperproteinaemia, hypoalbuminemia, hypergammaglobulinemia, hyperbilirubinemia), which normalised with treatment. Lactate dehydrogenase activities did not differ significantly before and after treatment, except in cats with a relapse and one non-responder, which had markedly elevated values at the time of diagnosis. Analysis of archived blood samples using ELISA revealed significant differences in concentration of acute-phase protein haptoglobin (p = 0.004) and pro-inflammatory cytokine tumour necrosis factor-α (p = 0.028) before and after therapy. Therapy didn't elicit any statistically significant changes in concentrations of ferritin, interleukin- 1β and interleukin- 6.

Our findings demonstrate that successful treatment of FIP leads to highly significant changes in most clinicopathological parameters, including haemogram-derived inflammatory markers. The latter could offer a simple, inexpensive and readily available alternative to the more commonly used acute phase proteins for monitoring FIP treatment. Successful therapy leads to a significant decrease in haptoglobin and an increase in tumour necrosis factor-α. In our study, cats with an unfavourable outcome showed a marked increase in lactate dehydrogenase activity before therapy, suggesting that this parameter could be a promising prognostic factor in larger studies.