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If your dog is afraid of thunderstorms or experiences motion sickness, your veterinarian might suggest giving them a mild sedative. One option is a drug called acepromazine, which is a common sedative prescribed for dogs. Acepromazine isn’t intended for human use. If a child or adult takes acepromazine by mistake, make sure to call Poison Control at 1-800-222-1222, as the drug can make them drowsy and cause their breathing to slow down.

When given to dogs at the appropriate dose, acepromazine can be an effective sedative. Learn more about the proper uses of acepromazine for dogs, common side effects, and its potential to interact with other medications.

Why Do Veterinarians Prescribe Acepromazine?

In veterinary medicine, acepromazine is used as a long-acting and mild sedative. “You get prolonged sedation with a single dose,” says Dr. Amy Attas, VMD of New York-based practice City Pets. “This drug also has anti-nausea properties, making it a good choice for pets who get motion sick while traveling.”

Acepromazine is inexpensive and can be dispensed in an oral or injectable form. The oral medication comes in different strengths, so you can give your dog the appropriate dose based on their weight. Alternatively, the veterinarian can administer the drug intravenously or subcutaneously, the latter referring to an injection just under the skin.

Basenji puppy hiding under furniture.
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The oral form of acepromazine tends to be less reliable, compared to the injectable medication. The oral medication can be absorbed at different rates, meaning the effect on dogs can vary. For instance, two dogs weighing 20 pounds might need a different dose of acepromazine to achieve the same level of sedation. The tablets are also very light sensitive, so it’s best to store them in a dark bottle and keep them in a cabinet away from sunlight, she says.

However, many veterinarians tend to reach for acepromazine less often because there is a variety of drugs that offer similar or sometimes better anti-anxiety effects with less side effects, such as trazadone. Unlike acepromazine, many of the newer sedatives are reversible. If you give a dog a stronger dose than what’s needed, you can give a reversal medication, and the dog is no longer sedated. The only way to get acepromazine out of your dog’s system “is time and supportive care like giving fluids,” she says. “So, there are situations where these newer drugs are considered safer because of the potential to reverse them.”

If you plan on using acepromazine for mild sedation or travel purposes, her advice is to do a test run. Before taking your dog on a car ride or airplane trip, try giving them the dose recommended by the vet. See if it provides the desired level and length of sedation for your dog. If it doesn’t, speak with your veterinarian before changing the dosage.

Golden Retriever sitting in the backseat of a car with children.

Side Effects and Drug Interactions

Acepromazine has several side effects and can also interact negatively with other medications and chemicals. In addition to consulting with your veterinarian, keep in mind the following side effects and drug interactions:

Prolonged Sedation

Acepromazine isn’t a good option if your dog needs to be sedated for a short duration. This drug can cause sedation for six to seven hours, particularly when given to older dogs. Also, acepromazine shouldn’t be given to puppies or dogs with liver disease.

Third Eyelid Effect

In addition to the upper and lower eyelid, dogs have a third eyelid called the nictitating membrane, which originates in the corner of the eye and sweeps across the eye diagonally. Normally you can’t see the third eyelid, but taking acepromazine can cause this eyelid to come out. If you’re not expecting it, this effect can be alarming since the membrane may cover two-thirds of the eye.

This side effect isn’t the same as a condition called cherry eye, which occurs when the gland on the underside of the third eyelid is swollen and everted, she explains. Upon taking acepromazine, the gland wouldn’t appear red and inflamed. Instead, you would see the tan or pink-colored third eyelid covering the surface of the eye. “The third eyelid won’t go back in until the effects of the drug are gone,” she says.

Drop in Blood Pressure

Taking acepromazine can cause a decrease in your dog’s blood pressure. This can be especially concerning if your dog already has low blood pressure due to another condition. You should be cautious when using acepromazine with narcotics (i.e., drugs that provide pain relief) because the combination can cause a decrease in blood pressure. It’s best to avoid giving your dog acepromazine at home if they’re on narcotics.

Another risk factor for low blood pressure is dehydration. When you’re giving this drug to your dog, make sure they’re “healthy and well hydrated, so we don’t get alarming drops in blood pressure,” she says. Since dogs with conditions like diabetes, Addison’s disease, and kidney disease tend to get dehydrated, it’s best to avoid giving them acepromazine.

Flea Treatment Interaction

Some flea collars and environmental flea treatments contain chemicals called organophosphate insecticides, which are chemicals used for killing insects on food crops and for controlling mosquito populations. Since these chemicals interact negatively with acepromazine, you shouldn’t use them together.

Gastrointestinal Medication Interaction

Acepromazine interacts negatively with medications used to treat constipation or disorders that prevent the gastrointestinal tract (GI) from functioning properly. These include medications like cisapride, which helps improve the movement of the GI tract; metronidazole, which helps treat diarrhea; and metoclopramide, which can cause neurologic symptoms when used with acepromazine.

You should also avoid using acepromazine with ondansetron (sold under the brand name Zofran), which is an anti-nausea medication. Another combination to avoid is using antacids, which can increase the sedating effects of acepromazine, she explains.

Beagle laying down on the carpet indoors.

When to Avoid Giving Your Dog Acepromazine

Acepromazine doesn’t have any analgesic (i.e., pain relief) properties. If your dog requires pain control, the vet may administer an opioid along with acepromazine. “This has to be monitored to make sure that the blood pressure doesn’t drop,” Dr. Attas says.

Acepromazine is also a poor choice if your dog has anxiety or phobias, like a fear of thunderstorms. “Even though it’s a sedative, it doesn’t have any antianxiety properties,” she says. When dogs are sedated with acepromazine, they still experience anxiety. And because they lose their mobility while sedated, they might feel even more anxious because they can’t move or get away from the source of their fears, she adds.

Some breeds have difficulty metabolizing this medication, which can make them more sensitive to the effects of acepromazine, she says. These breeds include the Greyhound, Whippet, Saluki, and Afghan Hound. There have also been reports in the UK that some lines of Boxers have an exaggerated response to acepromazine, but this seems to berare..

Aside from the risks to Sighthounds, some Collie breeds have the Multidrug Resistance 1 (MDR1) gene mutation, which affects how dogs metabolize acepromazine. If you’re concerned about your dog experiencing this effect, your vet can test for this gene mutation. In general, it’s best to avoid using acepromazine with Collie breeds.

This article is intended solely as general guidance, and does not constitute health or other professional advice. Individual situations and applicable laws vary by jurisdiction, and you are encouraged to obtain appropriate advice from qualified professionals in the applicable jurisdictions. We make no representations or warranties concerning any course of action taken by any person following or otherwise using the information offered or provided in this article, including any such information associated with and provided in connection with third-party products, and we will not be liable for any direct, indirect, consequential, special, exemplary or other damages that may result, including but not limited to economic loss, injury, illness or death.
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