Unless he is having cluster seizures, in which case he should be taken to an emergency bet, do not home-medicate your dog
for seizures. A singular, isolated
seizure can indicate anything from low blood sugar to idiopathic epilepsy and should never be medicated for at home until a veterinarian has examined the dog and has given his opinion on what the cause was and whether or not treatment is even necessary. Just hang in there until the vet is open and call the office as soon as you can.