Hello Vanessa - welcome to the forum. I have never had an epileptic dog so I don't have any personal experience. I have previously read up about taurine but in relation to heart disease - cannot remember reading about epilepsy. As you doubtless know, taurine is an amino acid and Dogs Naturally
has this to say about it: "One of the effects of Taurine in the body is as a controller of nervous impulses, and supplementing your dog’s diet to give him higher levels can raise the threshold at which fits are triggered."
According to Canine Epilepsy Guardian Angels
website it is considered to be a safe supplement, the dose being 200 to 1,000 mg. per day.
You asked about food containing taurine and I remember that it is mainly found in meat proteins so it might be worth considering something with a higher meat content. Arden Grange Adult has 27.2%. However, the Wainwright's will boost that somewhat, dependent on how much you are giving.
There is an article about taurine on this this website here.
At the bottom of the page there is a link 'Find foods containing taurine' and if you click on that there are three pages of dog foods to choose from. A few of them score 4 stars and above and have a high meat content. Applaws looked promising but contains Rosemary extract. The other ones that meet this criteria and which do not contain rosemary (as far as I can see) are:Alpha Spirit
Natures Way Mature and Light
Taste of the Wild
Ziwi Peak 'Daily Dog'
Please check the recipes out yourself to be sure about the rosemary and to determine whether any of them would be suitable.
Raw complete may be worth considering because taurine is reduced by cooking so it follows that there will be more of it in raw meat and fish. If you do consider this then it would be best to discuss with the manufacturer.
As your dog gains weight easily you will need to be very careful about how much you give as these are high quality/protein products. Dogs often need quite a bit less in quantity. If you do transition to one of them then do it slowly and be sure to weigh the food using 1g divisions digital scales, be it dry or wet.
The only other thing I can think of is that with regards to the therapeutic dose of taurine (given above as 200mg to 1000mg) it might be that the taurine in these products do not meet that level. The amount per 100g is not given on the food label so you would have to speak to the manufacturer about it. I think it might be useful to discuss this with the vet and ask if it would be best to give taurine as a supplement. Obviously you should discuss any changes with the vet too.
Please post back and let us know what you decide and how your dog is. We are interested and the information might be of use to someone in the same position as yourself.