The denaturant makes the alcohol taste bad. When a denaturant is added to alcohol it is called denatured alcohol or Alcohol Denat. Denatonium Benzoate is a common denaturant. It a quaternary ammonium compound that is considered the bitterest compound known. Quassin, Brucine and Brucine Sulfate are bitter alkaloid compounds obtained from plants.
Well, there can be some irregular pacing, breathing before the seizure. That can last from a few minutes to 30 minutes or more. The seizure itself should not be longer than a few minutes. Anything over 4-5 minutes is a huge risk for brain and body injury. After the actual seizure, a pet can remain disoriented, but they are at least responsive, for another few minutes to hours.
Talk to your vet. Most seizures last only a few minutes, however it can take longer for a dog to recover. You can try clapping your hand and calling her name to help snap her out of it. If it is lasting more than 3 or 4 minutes and she seems to be having trouble breathing you need to get her to the vet.