Epilepsy affects 0.5-5% of dogs and with appropriate management, most affected dogs can achieve good quality of life despite recurrent seizures.
Epileptic seizures cause acute welfare harm through the seizure itself - loss of consciousness, convulsions, involuntary urination and defecation - and the post-ictal period of confusion, fear, and disorientation that follows. Dogs have no understanding of what is happening to them during a seizure, and the disorientation afterwards can be prolonged and distressing. Between seizures, antiepileptic drugs may cause sedation, polyphagia, and weight gain. The welfare of epileptic dogs depends heavily on balancing adequate seizure control against medication side effects - the goal being minimum seizures with maximum quality of life, not necessarily zero seizures at any cost.