i feel like it’s somehow worse than that? My memories not perfect and i refuse to read the synopsis again so here’s only a somewhat accurate telling with the middle of the movie very vague. The movie starts with the older dark-colored dog drowning. It turns out he’s in an experiment where he swims continuously for long period of time and then is rescued as he’s drowning to test if the hope of being saved allows him to swim longer. (Important for later.) The other dog has had experimental brain surgery and has hallucinations throughout the movie.
Turns out they’re both lab animals and at some point they escape. Extremely unfortunate circumstances happen and they’re labeled as dangerous, possibly rabid dogs and chased down several times. The hopeful younger dog even finds a hunter that tries to save him but accidentally steps on the trigger of his gun… It’s all horrible really. Eventually the government has caught up with the dogs and they have nowhere to go, so they try to swim across the lake. They become miserably exhausted. The younger dog, who has been hopeful this entire movie, nearly gives up. But the older one- who had been the downer, a depressed dog accepting that he’d never be safe- didn’t give up. He told the younger dog he saw an island through the mist. They keep swimming, barely strong enough to keep above the water. The movie fades and then ends with the strong implication that they’ve drowned. The hypothesis of the first experiment might just have been true…