A Survey of Feline Inflammatory Hepatobiliary Disease Using the WSAVA Classification System
Feline Inflammatory Hepatobiliary Disease (FIHD) has been reported to be the second most common hepatic disease of cats in the United States. The primary goals of this study were to categorize a clinical population of cats with FIHD based on the recently published WSAVA classification system, to make clinical comparisons between the separate types of FIHD, and to perform real time polymerase chain reaction (RT-PCR) on paraffin embedded hepatic tissue in attempts to isolate bacterial DNA.
Seventy-four cases were included in the study. Cases were divided into the following groups: acute neutrophilic cholangitis (ANC), chronic neutrophilic cholangitis (CNC), acute lymphocytic cholangitis (ALC), and chronic lymphocytic cholangitis (CLC) by one pathologist (TVW). Medical records were reviewed for information pertaining to signalment, presenting clinical signs, physical examination findings, clinicopathologic data, imaging findings, cytologic findings, culture results, histopathologic results, and outcome. Paraffin embedded liver tissue was obtained from cases in which it was available (n=40) and from control cases with no evidence of inflammatory hepatobiliary disease (n=50). DNA was extracted using the QiaAmp DNA Mini Kit, (Qiagen) as described by the manufacturer. Amplification and DNA detection were carried out in a Smart Cycler (Cepheid) using 16S rRNA primers. For categorical variables, the chi-square test was used to compare the four groups. For continuous variables, the Kruskal-Wallis test was used. P<0.05 was considered significant.
Thirteen cats had ANC, 31 had CNC, 14 had ALC, and 16 had CLC. The median age for all cases included in the study was 11 years, with no significant difference between groups. 63.5% of cats in the study were male. No breed predilection was found. There were no significant differences between groups in the frequency of any clinical signs or physical examination findings. Cats with CNC were significantly more likely than cats in any other group to have increased ALT, GGT, total bilirubin, total protein, and globulin measurements. A significantly higher percentage of cats with CNC had bile duct obstructions compared to cats with other forms of cholangitis. RT-PCR was positive for the presence of bacterial DNA in 6 of the 40 cases in which paraffin embedded liver tissue was available, and in 5 of 50 control samples. Sequencing of the positive samples showed that they were all most consistent with contaminants.
Our conclusions are that (1) CNC is the most common form of inflammatory hepatobiliary disease in cats, and (2) cats with CNC are more likely to have increased ALT, GGT, total bilirubin, total solids, and globulin levels, and to have bile duct obstruction than are cats with other forms of inflammatory hepatobiliary disease. Real time PCR technology used in this study did not readily document bacterial infection in paraffin embedded liver tissue samples.