There's an excellent product you can get called Zylkene - you'll need the specific cat version:
Zylkene is classified as a food supplement It is made from a milk protein. The active ingredient is a peptide that has the ability of impacting brain receptors. This action has a soothing effect on the animal. It is effective for both cats and dogs. It can be purchased in three different sizes of capsule and the choice is determined based on the size of the pet to be treated
The pills can be opened and the contents sprinkled on food or the entire capsule can be given orally in the original form once a day. Most animals find it palatable and owners find it easy to administer. It is suitable for both a short-term treatment, which could be for a few days, or for longer periods if needed. Usually a course is given from between 2-4 weeks . Then the situation is re-assessed. If in doubt ask your vet.
Zylkene soon helps animals to handle many stressful situations. It may also be a solution for several behavioural problems,
It is advisable to begin administration at least 8 days before expected stressor, when possible. The medicine should be given once every day and can be doubled if the situation is exceedingly stressful.
You almost certainly won't observe an immediate change in your pet however little changes could possibly be seen within a few days.
It's available from pet stores & online, etc. It's perfectly safe, and whether used for temporary situations such as fireworks etc, or for longer term situations, it's quite safe to use. I emailed the manufacturer to check that they were safe to try for seizures, and got a positive reply really quickly.
We have a large dog who started getting seizures each time the groomers came to bath/clip our two. The vet decided she was too young to start taking seizure medication, so I found that and he thought it an excellent idea.
We start giving her one capsule in her food three days before the groomers are due, and continue it for 4 days after. In the two years we've been using it, she's only had one seizure, and that was 8 months ago when the whole household was going through a very stressful period.
Definitely worth a try, and if that fails, the vet may be able to give you something stronger.
We adore our dogs, and I especially love this big girl we have ...love her to bits!