A 9-month-old Golden Retriever is admitted for routine ovari…

A 9-month-old Golden Retriever is admitted for routine ovariohysterectomy. The patient weighs 40 lbs, and the veterinarian wants to use the following pre-anesthetic regimen:  Butorphanol (10 mg/ml) IM at 0.2 mg/kg; Acepromazine (10 mg/ml) IM at 0.05 mg/kg; Atropine (0.02% solution) SQ at 0.02 mg/kg. How much Butorphanol should be administered?