The melatonin stopped my dog’s seizures. While doing some research online, I discovered that rosemary extract and a dye called red 40 can cause seizures in small dogs. I also covered this in a 2009 column:DEAR DR. FOX: As you have written before, red dye 40 may cause seizures in dogs. \"Natural flavoring,\" meanwhile, could mean monosodium glutamate (MSG), which can also cause seizures. Rosemary extract is used as a preservative, and its use should be reconsidered since it too can cause seizures as you have experienced.