Dogs don't do well on long term steroid treatment. Are you sure it's prednisone/prednisolone that he's taking? What is he taking the steroid for? Did he have seizures BEFORE starting the corticosteroid? How long has he been taking the corticosteroid? These are all important questions before an answer can be attempted.
Do you even know what prednesone is? If not, you should .... especially the down side.
Hi. You say prednisolone isn't working as well as it did ... this concerns me, if what you mean is PREDNISONE (the canine variety of prednisolone). How long has your dog been taking prednisolone? This is a very powerful drug that should not be given long term. It can cause some severe and very damaging side-effects. Prednisolone does not cause or treat seizures, but it can create some severe symptoms and primaryt conditions that can lead to a dog having seizures. Talk to your vet straight away and start a diary of seizure events, describing how and when they happen. This information will be useful to your vet.
Tony
This is a public forum and I don't believe there have been any Vets on here for a long time. Some may be able to offer advice but you really should contact your treating Vet. You may try a search for seizures on the site and find some past discussions.