cat eating after b12 injection reaction to shot overdose? Vitamin B12 for Cats: 7
Description
Temporarily cut out eggs, dairy, and cruciferous vegetables until the flare-up subsides

The duration for B12 to work varies from person to person
Here is the problem

The joint that is affected may also appear to be red and swollen, but this is often indicative of a more serious condition that should be examined by a joint specialist promptly to ensure that there is no infection that is present
