Among people with epilepsy or who have children with epilepsy, its pretty common to hear discussion about 'seizure dogs'. These are either pets or specifically trained dogs that can predict when a seizure is going to happen, sometimes up to an hour before. They are somewhat rare but certainly a known phenomenon.
Apparently the training is a bit hit and miss, some dogs can do it and some can't. Training a dog to react to a seizure that is actually happening right now is quite a lot easier, and still very useful (e.g. train it to run to parents room, barking).
edit: also, one hears of scams where people claim to be able to provide seizure dogs but dont, so bear that in mind.
Apparently the training is a bit hit and miss, some dogs can do it and some can't. Training a dog to react to a seizure that is actually happening right now is quite a lot easier, and still very useful (e.g. train it to run to parents room, barking).
edit: also, one hears of scams where people claim to be able to provide seizure dogs but dont, so bear that in mind.