Mar Vista Animal Medical Center

3850 Grand View Blvd.
Los Angeles, CA 90066





5 mg, 10 mg & 25 mg



Although acepromazine has several actions that might be useful, it is mostly used as a tranquilizer. Strong anti-nauseal properties make this medication an excellent choice for traveling pets prone to both excessive restlessness and motion sickness.

Acepromazine also can stabilize the rhythm of the heart in certain situations. This is especially helpful for highly sensitive patients who get so frightened they can actually suffer a "heart attack" from fear. Acepromazine not only allays the fear through tranquilization but helps keeps the heart rhythm stable.

Acepromazine is commonly used to prepare animals for general anesthesia.

Acepromazine is also classified as an antihistamine; however, due to its healing tranquilizing properties it would not be used as such.

There is some controversy about the use of this medication in situations that stimulate a panic reaction (thunderstorms, fireworks etc.). While acepromazine makes patients drowsy, there is some thinking that it heightens the perception of loud noises. Many behaviorists feel that the benzodiazepine group of tranquilizers, especially alprazolam, may be superior in these situations though acepromazine has certainly been the mainstay for pet tranquilization for decades.

In summary, Acepromazine is used for:

  • Tranquilization
  • Motion sickness
  • Alleviating Fear



Acepromazine is a long lasting tranquilizer. It should be expected to last 6-8 hours.

In extremely rare instances, some pets exhibit aggressive behavior as a reaction to acepromazine.

Acepromazine drops blood pressure by dilating blood vessels. The strong tranquilization effect precludes the use of acepromazine in the treatment of high blood pressure.

Dogs and cats on acepromazine typically bring up their third eyelids. Many pet owners are unaware that their pet has an extra eyelid so we have included the graphic below. There are no negative effects to the prolapse of the third eyelid but it is helpful to the owner to recognize this side effect so as not to become alarmed.

Acepromazine use can impart a pinkish or even brownish-red color to urine. This is normal and is of no harm or significance.

third eyelid

(original graphic by

Many dogs of herding breed (especially collie) heritage have been found to have a mutant gene for what is called the "P-glycoprotein." The P-glycoprotein is involved in keeping certain biochemicals/drugs OUT of certain body tissues. Dogs with mutant P-glycoproteins, allow more biochemicals/drugs INTO certain body tissues. In the case of acepromazine, dogs with this mutation will be sensitive to acepromazine and require approximately 25% less of a dose than might be expected.

Approximately 35% of Collies have a genetic mutation creating a non-functional P-glycoprotein. This allows for acepromazine doses that would normally be blocked from the central nervous system to gain access to it. Other herding breeds also have a tendency to express this mutation. There is now a test for P-glycoprotein mutation so that these dogs can be identified. This is a DNA test using an oral swab. Test kits can be ordered directly from the Washington State University Veterinary School via



Acepromazine should not be used with organophosphate insecticides. This type of insecticide is not commonly used anymore but might be expected in flea collars and in outdoor flea treatment products. If you are not sure if an insecticide is organophosphate based, please ask your veterinarian. A full month is recommended between the use of acepromazine and any organophosphate parasite/insecticide products.

Giving acepromazine in conjunction with antacids will decrease the effect of acepromazine.

The use of acepromazine in conjunction with quinidine (a heart medication) could lead to adverse heart reactions.

Concurrent use of acepromazine and metoclopramide (a nausea medication), can enhance the potential for neurologic side effects of metoclopramide.



  • Tablets should be stored where they are not exposed to light.
  • Acepromazine is not consistently absorbed into the body when given orally. This means that some pets are hardly tranquilized while others are heavily sedated. More consistent results are obtained with the injectable product.
  • Acepromazine is best not used in patients where circulation is in question. Acepromazine dilates blood vessels which leads to a drop in blood pressure. Injured patients or patients in shock should not have this medication.
  • Classically, acepromazine has been said to lower the threshold to seizures and for decades it has been recommended to avoid acepromazine in patients with known seizure disorders. More recent scrutiny has called this dogma into controversy. The jury is still out with regard to the true seizure-inducing potential of this medication.
  • Acepromazine should not be used in anemic patients. By dilating the blood vessels in the spleen, acepromazine use leads to increased red blood cell storage in the spleen, leading to an approximately 5% drop in red cell count. This is not important in normal pets but if there has already been a blood loss this drop in red cell count could be significant.
  • Acepromazine should not be used in patients with known liver disease. Acepromazine is removed from the body by the liver and if the liver is not working, tranquilization can be markedly prolonged.
  • Sighthounds such as greyhounds, whippets, salukis, wolfhounds etc. are sensitive to the effects of acepromazine. A different medication may be a better choice.

Acepromazine use can impart a pinkish or even brownish-red color to urine. This is normal and is of no harm or significance. 


The answer is that no one knows for sure and no hard proof or scientific studies are available for review. Several anectdotal reports exist of boxers dangerously dropping their heart rates after routine doses of acepromazine. This had generally been thought to be chiefly a problem in the U.K. for a group of genetically related dogs, but recently the University of California at Davis Veterinary School Anesthesia Service issued a memo which led more U.S. veterinarians to take the rumors more seriously. In this memo, the anesthesia service describes three individual boxers suffering adverse reactions (respiratory arrest in one and severe drop in heart rate in two) and suggests that acepromazine be considered contraindicated in this breed.


While it appears to be prudent to avoid acepromazine in the boxer, it is important to realize that acepromazine has been used widely in boxers with no problems and that adverse events are unusual.

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Page last updated: 8/12/2016