Use: Acepromazine is a commonly prescribed tranquilizer for animals. It decreases anxiety, causes central nervous system depression, and a drop in blood pressure and heart rate. It may be used in conjunction with atropine as a pre-operative medication for anxiety and for its antidysrhythmic effects. Oral acepromazine may be prescribed to prevent motion sickness, to temporarily reduce itching and scratching due to allergies, or prior to office visits, nail trimming or grooming appointments if the animal is too fractious to handle safely without sedation. Some veterinarians are reluctant to prescribe acepromazine for travel anxiety when the animal may be exposed to temperature extremes, such as during plane travel, or when there may be limited access to veterinary care. Other drugs used for travel anxiety/motion sickness include meclizine, diphenhydramine, and diazepam. Occasionally, animals (particularly cats) may have a paradoxical response to acepromazine and become excited, or aggressive.

Side Effects: Common: Acepromazine will cause hypotension, decreased respiratory rate and bradycardia. Dogs are particularly sensitive to cardiovascular side effects but cardiovascular collapse has also occurred in cats. Sudden collapse, decreased or absent pulse and breathing, pale gums, and unconsciousness may occur in some animals.  Rare: fatal interactions with anesthetics have been reported.  Acepromazine will cause a dose dependent decrease in hematocrit in both dogs and horses. This effect occurs within 30 minutes of administration and may last for 12 hours or more. The hematocrit in horses may decrease by as much as 50%.

Precautions: Acepromazine lowers blood pressure: it should not be used in animals that are dehydrated, anemic or in shock. Acepromazine should be avoided or used with extreme caution in older animals, or those with liver disease, heart disease, injury, or debilitation. If it is used in these animals, it should be given in very small doses. In some older animals, a very small dose can have a marked and very prolonged effect.

Acepromazine should not be used in animals with a history of epilepsy, those prone to seizures, or those receiving a myelogram because it may lower the seizure threshold. Acepromazine should not be used in animals with tetanus or strychnine poisoning. Acepromazine should be avoided in pregnancy or lactation. It should be avoided or used with extreme caution in young animals due to its effects on an animal's ability to thermo regulate. Dogs: Giant breeds and greyhounds may be extremely sensitive to acepromazine, while terriers may require higher doses. Brachycephalic breeds, especially Boxers, are particularly prone to cardiovascular side effects (drop in blood pressure and slow heart rate). Acepromazine should be avoided or used with great caution in these breeds.

Overdose will cause excessive sedation, slow respiratory and heart rate, pale gums, unsteady gait, poor coordination, and inability to stand. It may also cause sudden collapse, unconsciousness, seizures and death. Oral overdose should be treated by emptying the stomach along with monitoring and other supportive care. Phenylephrine and norepinephrine are the drugs of choice to treat acepromazine-induced hypotension. Barbiturates, or diazepam may be used for the treatment of seizures associated with overdose.

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