Brand Name: PromAce®

Available in 10 mg, 25 mg tablets, and injectable

How this Medication is Used 

Although acepromazine has several actions that might be useful, it is mostly used as a tranquilizer or sedative and it has been the mainstay for this role in pets for decades. Its sedative effects coupled with anti-nausea properties also make acepromazine a good choice for traveling pets who are prone to both excessive restlessness and motion sickness, especially if sedation is desired. 

Acepromazine generally should not be used alone to treat behavior problems in animals. For example, there is some controversy about the use of this medication in situations that stimulate anxiety (thunderstorms, fireworks, etc.). When used alone, acepromazine may worsen anxiety, so much so that the animal may become aggressive.  Animals may be more likely to respond to loud noises. However, when used with other drugs that help prevent anxiety, it can make the other drugs work better. An example is the “chill” protocol which includes gabapentin, melatonin, and acepromazine used in dogs to decrease anxiety before visiting a veterinarian. Effect

 In summary, acepromazine is used for: 

• Tranquilization or sedation
• Motion sickness 
• In combination with other drugs to treat anxiety or reduce stress.

Acepromazine is given 30 to 60 minutes before the triggering event.  When used in combination with other drugs to prevent anxiety, it is given 90 to 120 minutes before the event (such as an office visit).  Because many animals respond differently to acepromazine, you should discuss with your veterinarian whether or not additional doses should be given after a specific period. , Be sure to follow your veterinarian's recommendation on dosing. 

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Photo courtesy of MarVista Vet

Side Effects 

• Acepromazine is a long-lasting tranquilizer, generally lasting 6 to 8 hrs. However, it may not last as long in some animals and longer in others.
• Because an animal is less likely to be able to move away from an undesirable situation, acepromazine may worsen some behaviors.
• Medications, especially drugs like acepromazine, used to control panic situations are discouraged by the International Air Transport Association because the animal is not as able to move in response to stressful situations.
• 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 photo. This is not harmful but can be concerning to owners.
• Acepromazine use can impart a pinkish or even brownish-red color to urine. This is normal and is of no harm or significance. 

Herding Breeds

Many dogs of herding breed (especially collie) heritage have been found to have a mutant gene called the MDR-1 (also called ABCB-1) mutation. This gene codes 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 become more sedated than expected. There is now a test for the MDR-1 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. This website also provides information about which breeds of dogs are more likely to be affected. Because the dose of dogs with this mutation needs to be reduced, you should discuss using acepromazine if your dog is among the breeds at high risk of having this mutation.

Interactions with Other Drugs 

• Giving acepromazine in conjunction with antacids will decrease the effect of acepromazine.
• Acepromazine should be used cautiously in animals receiving other medications that decrease blood pressure.
• Phenothiazines (acepromazine is in this group of drugs) may decrease the efficacy of drugs used to manage epilepsy in humans.  It is not clear if this may also occur for acepromazine.
• Using acepromazine with the heart medication quinidine could lead to negative heart reactions. Heart rhythm disturbances can result when acepromazine is used at the same time as cisapride, ondansetron, or metronidazole.
• Concurrent use of acepromazine and metoclopramide (a nausea medication) can enhance the potential for neurologic side effects of metoclopramide.
• Although phenothiazines reduce vomiting that might occur when an animal is given an opioid, this must be done carefully to avoid too much sedation or not much of a decrease in blood pressure.
• Combining acepromazine with acetaminophen can lead to a significant drop in body temperature. 

Concerns and Cautions 

• Tablets should be stored at room temperature where they are not exposed to light. 
• Acepromazine may take 30-60 minutes to take effect.
• If you miss a dose, do not double up on the next dose. Give it when you remember to at the next dosing time, allowing at least the proper time between doses according to the label instructions.
• Some dogs may be more sensitive to the side effects of acepromazine compared to others. For example, breeds that are more likely to have the MDR mutation may become more sedated.
• Sighthounds such as greyhounds, whippets, Salukis, wolfhounds, etc., may be more sensitive to the effects of acepromazine and a lower dose may be used. It is not clear if boxers are more sensitive but it is not unusual for lower doses being used in boxers as well.  
• Acepromazine should be used very cautiously in patients who are at risk of developing or worsening hypotension. 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. 
• Phenothiazines are known to increase the risk of seizures in humans and are used very cautiously in persons with epilepsy. Although historically this was thought to be true of acepromazine. However, recently, studies in dogs with epilepsy have shown that the opposite may be true for acepromazine. It does not seem to worsen seizures and may decrease the risk of seizures. Nonetheless, it should be used cautiously in animals being treated for seizures.
• Acepromazine should be used with caution in patients with known liver disease as tranquilization or sedation can be markedly prolonged.

Are Boxers Sensitive to Acepromazine Side Effects?

The answer is that no one knows for sure, as no hard proof or scientific studies are available for review. Several anecdotal reports exist of boxers dangerously dropping their heart rates after routine doses of acepromazine. Dose reductions are frequently recommended for this breed to be prudent. Selecting a different tranquilizer should avoid the issue altogether.