Acepromazine (ACE) is a phenothiazine derivative used for its sedative properties. The primary mechanism of action of ACE is through inhibition of dopaminergic-2 receptors in the brain. It is a common belief that ACE lowers the seizure threshold. The purpose of this clinical study is to retrospectively evaluate the occurrence of seizures in dogs presenting with a history of seizures that were treated with ACE during hospitalization. A retrospective review of records from dogs that had a chronic or acute seizure history and received ACE was done. Factors evaluated included the presenting complaint, historical seizure information, ACE dosage and route of administration, reason for giving and length of hospitalization following ACE, occurrence of seizure activity post-ACE administration, time interval between ACE and seizure activity, and use of other medications. Thirty-one dogs qualified for the study, 20 males and 11 females. Age range was 3 months - 14.9 years. Presenting complaint was seizure in 28 patients, bite wound in 1 patient, ruptured cranial cruciate ligament in 1 patient, and hind limb paresis in 1 patient. Twenty-seven dogs did not seize after ACE administration within an average of 16.4 hours of observation (range: 0.25–66 hours). There was a known history of seizures in 22/31 prior to the day of presentation, and 15/22 were currently on maintenance anti-epileptic medication. Of the 16 not on anti-seizure medication at the time of presentation, 13 were started on phenobarbital. One was also started on potassium bromide, and 3 received no anti-seizure medication during hospitalization. All received at least one dose of ACE while in the hospital (range 1–5). Mean ACE dose was 0.029 mg/kg IV (range: 0.008–0.057 mg/kg; n=46), 0.036 mg/kg IM (range: 0.017–0.059 mg/kg; n=14), 0.53 mg/kg PO (n=2). Twenty-three received some form of anti-seizure medication in the hospital prior to being given ACE. Eight seizure episodes occurred 0.3–10 hours after ACE administration in 4. All 4 presented for seizures. The time interval between ACE administration and seizure activity was greater than that expected for measurable effects to be seen in one dog (10 hours). In conclusion, there is no clinical evidence that ACE administration at the listed dosages is associated with increased seizure activity in dogs with seizure disorders. A larger study group is needed to more thoroughly evaluate the safety of short-term ACE use in dogs with a seizure history.