One of my collies developed epilepsy about a year ago, he’s on max dosage of most of his meds now, and down to 1 seizure every 3 weeks.
Hes had a lot of seizures, but always while resting at home, he’s never had one while out walking, I think because his mind is so active when he’s out.
I don’t think a single seizure would be too much of a problem to deal with, but a cluster would – we’ve got a few doses of diazepam to use to deal with a long seizure or cluster, and in the cases where we’ve used them, he’s been ok to walk on lead shortly afterwards.
Worth getting some of them, as the longer a seizure goes on, the greater the effects on the dog.
Good luck, it’s not easy!