# Influence of Prednisolone Treatment on Serum Bile Acid Concentrations in Cats

## TL;DR

This study shows that prednisolone treatment in cats slightly increases bile acids but does not cause significant liver enzyme changes.

## Contribution

The first study to investigate the effects of prednisolone on bile acid levels and early liver enzyme changes in cats.

## Key findings

- Prednisolone caused a small but statistically significant increase in bile acid levels in cats.
- Liver enzyme activities (ALT, AST, ALP) decreased during treatment, contrary to expectations.
- GGT remained undetectable throughout the study period.

## Abstract

Corticosteroids like prednisolone are commonly used in veterinary medicine, including in cats. To date, the effects of corticosteroids on bile acid levels in cats have not been studied at all, and early changes in liver enzyme activities within the first days after treatment initiation have also not been investigated. In our study, we gave seven healthy cats a daily dose of oral prednisolone for one week and monitored their blood over two weeks to track changes in bile acids and liver enzymes (ALT, AST, ALP, and GGT). We found that bile acid levels increased slightly during treatment but stayed within or just above the normal range. Although this change was statistically significant, it is likely not clinically relevant. Interestingly, instead of increasing, liver enzyme activities actually decreased in the early days of treatment. GGT remained undetectable throughout. Our findings suggest that short-term prednisolone use causes a small, likely unimportant increase in bile acids in cats. The decrease in liver enzymes, which goes against common expectations, highlights the need for further research into the early effects of corticosteroids on the feline liver.

While corticosteroids affect bile acid metabolism in humans and dogs, their impact on serum bile acids in cats is unknown. Moreover, the early effects of corticosteroids on liver enzyme activity in cats are not well understood. We prospectively studied seven healthy cats (4–7 years) treated with oral prednisolone (1.1–1.5 mg/kg, median 1.28 mg/kg PO daily) for 7 days. Serum bile acids and liver enzyme activities (ALT, AST, ALP, GGT) were measured before treatment (day 0) and at days 2, 3, 8, 10, and 14. Statistical analysis used the Friedman test with post hoc comparisons to baseline. At baseline, bile acids were within reference interval (1–6.5 μmol/L) (median 2.1 μmol/L, range 1–3.2) and increased significantly during treatment with prednisolone to a median of 5.3 μmol/L (range 1.8–8.7) at d8, but remained below clinically abnormal levels. In contrast, AST, ALT, and ALP activities decreased significantly during prednisolone administration. GGT activities were undetectable at all times. We conclude that, although prednisolone significantly affected bile acids, the effect is likely of limited clinical relevance, as increases were minimal and remained below thresholds considered abnormal. Unexpectedly, transaminase and alkaline phosphatase activities decreased in the first days after administration. The reasons for this remain unclear.