Studies show that maintaining healthy glutathione levels may help reduce oxidative stress, improve liver enzyme balance, and support detoxification (NIH)
doi: 10.1152/ajpheart.01042.2003
It's important to note that Vitamin B12 injections should be used as part of a comprehensive treatment plan for FIP and not as a standalone solution
Nierenberg DW, Nordgren RE, Chang MB, et al
Side effects are typically rare and mild, such as slight pain at the injection site or mild dizziness
Therefore, it may be to your pups benefit to help a few connected systems at one time and alleviate the overall stress on the body (particularly, while you are getting to the root of the issues)