I tried a different approach.
The next day, while Fred was sitting on the dining room table looking very relaxed and trusting, I made my move. I approached him calmly and slowly. I praised him and stroked his fur, and at the same time I, uh, inserted the nozzle on the enema. Fred seemed to be okay with all of this. I gave the plastic bottle a squeeze. Then I gave it another squeeze. So far so good. Then, all of a sudden, Fred seemed to panic.