Just had a 5-weight Hereford steer, otherwise healthy, have a seizure. It lasted about 20 minutes with entire body shaking, unable to stand. It subsided and we put him through the chute. Temp 104.3. Has had all vaccines twice in last 30 days. Gave it Baytril and Banamine for fever. Calf kept in preconditioning lot with several other healthy calves. What could have caused the seizure?