
Hi, my cat is taking Doxycycline antibiotic for liver issues. Can I make him take antibiotic before eating?

So, you can strictly speaking, but there are risks.
Because doxycycline can be more likely to cause stomach upset, giving it without food may be more likely to lead to vomiting or a decreased appetite.
But even more important is the form of the doxycycline. If you have doxycycline tablets, you cannot give them without surrounding it with food or a treat to ensure the food bolus carries it to the stomach. You cannot "dry pill" doxycycline in cats, as this can lead to sores in the esophagus and something called an esophageal stricture.
In many cases, veterinarians, knowing this risk, will have doxycycline compounded into a liquid form, especially for longer courses. If you have a liquid form, there is no danger of sores and esophageal stricture, but you could still have a problem with stomach upset.