Diagnostic importance of adenosine deaminase and C reactive protein in cats with feline infectious peritonitis

The study aims at determining status of cellular immune response, acute phase response and revealing possible organ failure by defining serum adenosine deaminase (ADA-1) and C reactive protein (CRP) levels and variations in hematologic and biochemical parameters in cats with feline infectious peritonitis (FIP). Furthermore, the study targets at identifying diagnostic importance of adenosine deaminase (ADA-1) and C Reactive protein (CRP) levels which were measured first time in cats with FIP. FIP infection is more common in kittens and old cats with weak immune system including a difficulty in identifying the cats having the disease. Most of the healthy cats or the one that recovered from the disease carry it and continuously infect other cats. Additionally, in the event that immune systems of the cats that carry the disease become weak, FIP infection which is severe and vital can be developed because of the strong mutation skills of coronavirus. Cellular immune response is more important within these cats and it is asserted that FIP infection can develop easier when humoral response is high. Therefore, studies to reveal the status of cellular immune response and prognostic indicators in cats with FIP are needed in order to diagnose the disease. In the study, cats with suspect of FIP or clinically healthy cats were subjected to feline coronavirus (FCoV) antibody and antigen, feline immunodeficiency (FIV) antibody and leukaemia virus (FLeV) antibody rapid test kits. As a result of the tests, 20 cats that are only FCoV antibody or antigen positive and 10 clinically healthy cats of which all test kits are negative were included to the study. In addition to that, cats with FIP were grouped as dry form (n=10) FIP and wet form (n=10) FIP according to clinical, radiography and necropsy findings. Blood samples were collected into tubes with K3EDTA without anticoagulant. Blood samples with K3EDTA were used for hematologic analysis, whilst blood samples were used to separate sera and then used for biochemical analyses. ADA-1 and CRP levels in serum samples obtained from both cats with dry and wet form FIP and in peritoneal effusion samples of cats with wet form FİP were measured, using cat-specific ELISA. As a result of haematological analyses, leucopoenia (p<0,001), granulocytosis (p<0,001), monocytosis (p<0,001), lymphocytopenia (p<0,001) and erythrocytopenia (p<0,001) were determined in cats with FIP. Leucocytosis was resulted from the increases in granulocytes and monocytes. A modarete anaemia was determined in these animals. The biochemical analyses showed that ALT (p<0,01), LDH (p<0,01), ALP (p<0,01), TP (p<0,01) and globulin (p<0,01) levels of cats with FIP were significantly high, whilst albumin (p<0,01) and A/G rates (p<0,01) of cats with FIP were significantly low compared to those of cats in the control group. TP and G values of cats with dry form of FIP were significantly higher than cats with wet form of FIP (p<0,05). ADA-1 (p<0,001) and CRP (p<0,001) levels of cats with FIP were found to be significantly higher than those of cats in control group. High levels of ADA-1 and CRP were obtained in both serum and peritoneal effusion samples of the cats with wet FIP with a positive correlation of two parameters in serum and effusion levels. Whilst, significant variations took place in some of the analysed parameters in cats with FIP, some parameters showed similarities with the values of healthy cats. The possible reason to that might be explained by different age groups of the cats used in the study and process and severity xiii of the disease. Additionally, analysed parameters can be changed according to the infection in cats with FIP, it must be considered that normal values can also be found in cats with FIP. As a conclusion, FIP infection causes hematologic variations including lymphocytopenia, erythrocytopenia and leucocytosis which is resulted from granulocytosis and monocytosis. In addition to that, the infection negatively affects liver and kidney functions by causing hyperproteinaemia, hyperglobulinemia and hypoalbuminemia within cats. T lymphocyte activation, increase in ADA-1 and CRP which is positive acute phase protein that rises in inflammatory cases besides the decrease in albumin levels, a negative acute phase protein indicates the development of acute phase response in cats with FIP. The increase in ADA-1 levels is indicate the presence of activated cellular immune response resulted from T lymphocyte activation. The determination of increases in serum and peritoneal effusion of ADA-1 and CRP levels and the presence of positive correlation between them demonstrate that these parameters can be used to diagnose FIP infection in cats.