If you don't know where he came from and his history, you really shouldn't be breeding him.
Seizures can be treated with medication, and they don't always get worse. Many animals have seizures which are kept under control for the duration of their lives though careful monitoring and medication.
We are as gods to the beasts of the fields. We order the time o' their birth and the time o' their death. Between times, we ha' a duty. - Terry Pratchett.
"Men have forgotten this truth", said the fox, "But you must not forget it. You become responsible, forever, for what you have tamed. - Antoine de Saint-Exupéry