Brakes

I hit brakes to avoid hitting an opossum. I was traveling at thirty mph. After hitting the brakes I tried to slow down to turn around to see if the animal was still alive. When I depressed the brake pedal I had to press down and the car was difficult to stop. The brake pedal did not sink and retracted. I slowed way down and tapped the brake. I heard an intake of air. There was no wheezing. I drove home and when I checked under the vehicle there was no fluid on the ground. Please advise. Thank you.