Acepromazine is prescribed as a sedative for dogs suffering from anxious reactions to stressful events such as thunderstorms, fireworks or travel. Motion sickness can also be treated with acepromazine. Used in combination with opioid pain relievers, acepromazine helps dogs recover from surgeries and is often used before the procedures to make dogs easier to handle for veterinary staff without stressing the dog.
The normal prescribed dosage for acepromazine is 0.25 milligrams to 1 milligrams per pound of body weight (0.5 to 2.2 milligrams per kilogram). So, for example, a 40-pound dog would be prescribed a minimum dose of 10 milligrams, a 100-pound dog 25 milligrams per dose. Acepromazine comes in 10 milligrams and 25 milligrams size tablets, scored in quarters for easy splitting.
The minimum effective dose of acepromazine should be administered 45 minutes to one hour before the expected stressful event. The drug becomes effective 20 to 30 minutes after ingestion and the sedative effects should last several hours, though the drug does remain in the dog's system for up to three weeks.
Proper dosage should calm the dog and make it sleepy. Lack of coordination can also result; a sedated dog should be watched closely to avoid injury to itself or others. Puffiness of the nictitating membrane, or third eyelid, is common, as is a pink coloration to the urine.
Veterinarians say an overdose of acepromazine is difficult to accomplish, and high doses of the drug will make most dogs sleep for 12 hours and little else. However, a dangerous overdose is possible. Signs of an overdose include severely lowered blood pressure (hypotension), pale gums, excessive sleepiness, arrhythmic heartbeat (bradycardia) and seizure. If an overdose is suspected, seek veterinary attention immediately. The veterinarian can treat overdose symptoms until the acepromazine is metabolized out of the dog's system by the liver.
First-time users of acepromazine should begin at the lowest recommended dose. Observe the dog's behavior and symptoms before increasing or decreasing the dosage. If acepromazine is given post-op and prescribed as ongoing treatment, the dog's liver will become adapted to the drug and more efficient at removing it; dosage will gradually need to increase to remain effective. Once the dog has ceased use of acepromazine, if it ever needs it again, it should begin at the lowest dose again, because acepromazine is non-addictive; a pattern of effective dosage is not retained in the liver.
Certain breeds react poorly to acepromazine. Boxers are known to have exaggerated reactions to minimal doses of acepromazine, such as bradycardia and hypotension. Veterinarians can still use acepromazine in combination with atropine for breeds that are sensitive to the bradycardic effects. Terrier breeds are known to metabolize this drug faster than other dogs, and show resistance to its effects. Very aggressive dogs are unpredictable on this sedative--acepromazine induces a sleepy state that can be overcome by adrenaline long enough for the dog to deal with the perceived threat and then return to sleepiness. Do not allow small children to bother a sedated dog.