Acepromazine (also known as PromAce®) is a tranquilizer which can be used for the treatment of anxiety, itching and motion sickness, or as a pre-med before general anaesthetic. Originally it was also used for controlling behavioral problems but has since been succeeded by other drugs with fewer side effects.

It’s important to understand that the drug works mainly by preventing animals from showing symptoms of anxiety and from reacting to the situation, but does not do much to relieve the anxious emotions and fear. This means that a dog on acepromazine can seem relaxed while in reality they are feeling scared.

Safer alternative: If you were considering this medicine as a calming aid it is often safer to use Benadryl(®). Benadryl containing diphenhydramine is usually given to dogs at a dosage of 1 mg/lb body weight to provide effective anxiety relief, perfect for thunderstorms or fireworks night. To learn more see our page about diphenhydramine.

Recommended Dosage

Note: This drug can cause several adverse effects including effects on the heart, it is important that you avoid use unless you have your vet’s approval and instructions.

When using acepromazine tablets to treat dogs the usual dosage is 0.25 – 1 mg/lb. This may be reduced to avoid hypotension when opiates are also being given. A 1 mg/lb dosage is shown on the chart below.

Chart of the acepromazine dog dosage

Lowering the dose by 25% is recommended when treating pets with the MDR1 gene mutation to avoid over-sedation. The MDR1 gene mutation is very common in the following breeds:

  • Collies
  • German/Australian Shepherds
  • English/Old English/McNab/Shetland Sheepdogs
  • Longhaired Whippets
  • Silken Windhounds
  • Skye terriers


The PromAce package insert recommends a dosage of 0.25 – 0.5 mg/lb by injection, but many vets prefer a smaller dose. We recommend 0.012 – 0.09 mg/lb with an upper limit of 3 mg total. When injected IM a slightly higher dose of 0.046 – 0.11 mg/lb can be used, again with an upper limit of 3 mg. Higher amounts are probably safe but increase depression.

Example: A 30 lb dog could be given 30 mg by mouth or 2.7 mg by IV injection.

How Safe Is It?

In many cases, the risks of using ace outweigh the benefits and safer medicines should be chosen instead. As an example, acepromazine can lower blood pressure and affect heart function so it’s often best to use different medicines for anxiety relief and motion sickness. Because dogs seem to be more sensitive to the effects on the heart than other species it is even more important that you do not use this medicine without speaking to your vet.

It may be unsuitable for:

  • Racing dogs *
  • Puppies or generally debilitated pets
  • Dogs with heart/kidney/liver disease or hypotension

* The drug may not be used within 4 days of a racing event.

Certain breeds of dog including greyhounds and giant breeds are often more sensitive to this drug while terriers seem to handle it well. The effects of the drug tend to last longer for older pets.

Pregnancy/nursing: Avoid use in pregnant or nursing animals if possible.

Safety Guidelines

We recommend these guidelines when you begin treating your pet with this drug:

  • Do not attempt use without your vet’s consent and guidance
  • Notify your vet of any medical conditions your dog suffers with
  • Avoid giving your dog other medicine in conjunction unless told to do so by a vet
  • Practice caution when treating old or agressive pets and herding breeds
  • Practice extra caution when treating giant breeds or greyhounds
  • Monitor body temperature during very cold or hot weather

Even though the medicine is a sedative it can cause aggressive animals to become more aggravated and easily startled.

What Is It Used For?

Acepromazine is most often used as a sedative or as a pre-med but can also prevent itching and travel sickness. It does not act as an effective painkiller. For pain relief, tramadol is a better option.

Side Effects

During treatment your pet may experience these adverse effects:

  • Seizures
  • Drop in blood pressure
  • Drop in heart rate
  • Circulatory collapse
  • Aggression
  • Gastric effects (vomiting/constipation)

Atropine can be given in conjunction to counteract the drop in blood pressure and diazepam can control seizures if they occur.

Why has my pet’s urine gone a funny color?

This medicine can turn urine pink or brown, do not be alarmed as this is completely normal.


Acute overdoses are not usually serious. Dogs receiving overdose amounts of up to 100 mg/lb in trials experienced hyperaemia and pulmonary edema, but there were no fatalities. Overdose reports list symptoms such as loss of coordination, extreme sedation and leaning to one side or laying down. If you suspect an overdose please contact your vet or the ASPCA Pet Poison Helpline (800-213-6680).


Dr. Morgan
Plumb’s Veterinary Drug Handbook (sixth edition)