Phenobarbital Killed My Dog?

When I searched online ”Phenobarbital killed my dog”, I read this following heart-breaking story in a dog forum.

I was out of town for the weekend and my dog was being boarded at the local animal hospital. I got a call from the hospital on Sunday morning telling me that my dog had been seizure free for 24 hours and they were going to start weaning him off the phenobarbital. I told them to go ahead with the weaning process and I would pick him up on Monday afternoon. Monday afternoon I went to pick up my dog and they told me he had started seizing again early that morning and they had increased his dose of phenobarbital. They said he was doing better but they wanted to keep him overnight for observation. I left feeling reassured that my dog was in good hands and would be coming home the next day.

Tuesday morning I got a call from the animal hospital telling me my dog had passed away during the night. I was devastated. My dog wasn’t even three years old. The vet told me that sometimes dogs have a reaction to phenobarbital and it can cause liver failure. We were so heartbroken when our dog died unexpectedly. We had no idea that the phenobarbital he was taking for seizures could have such deadly side effects. We just want to warn other pet owners out there to be careful with this medication. Our dog was such a sweetheart and we miss him dearly”.

This is truly a sad story. But can Phenobarbital kill a dog? We will answer this question along with other things related to Phenobarbital and dog. Let’s start with the most burning question:

Can Phenobarbital Cause Death in Dogs?

Phenobarbital is a barbiturate class drug used as a sedative and anticonvulsant in humans and animals. In dogs, it is commonly used to treat seizures and epilepsy. Phenobarbital can be an effective treatment for seizures, but it also has the potential to cause serious side effects or even death at very high doses.

The most common side effects of phenobarbital include drowsiness, dizziness, loss of coordination, and upset stomach. More serious side effects include liver damage, low blood pressure, slow heart rate, and respiratory depression. If not treated promptly, these side effects can lead to coma or death.

How Much Phenobarbital is Lethal for Dogs?

The oral dose for dogs is 2-4 mg/kg body weight given once or twice daily. For intravenous administration, the recommended dose is 4-6 mg/kg body weight given slowly over 5-10 minutes.

If your dog ate a lethal dose of pentobarbital, it would need to eat almost its own weight in contaminated food. This is because the lethal oral dose of pentobarbital for a dog is about 85 milligrams of the drug per kilogram (2.2 lbs) of body weight. (source)

That means, a healthy 15-pound dog would need to eat approximately its own body weight in food in order to receive a lethal dose of pentobarbital, if the food was poisoned at a level of 81 parts per million.

In general, phenobarbital is considered to be a very safe drug for dogs when used at the recommended doses. Side effects are rare but may include drowsiness, dizziness, incoordination, vomiting, and diarrhea.

Can Phenobarbital Make Seizures Worse in Dogs?

Phenobarbital is a common medication used to control seizures in dogs. While it is effective for many dogs, there is the potential for it to make seizures worse in some cases. If your dog is seizure-free on phenobarbital and then has a seizure, it may be because the dose of phenobarbital was too low or because the dog’s body metabolizes the drug differently than expected.

If this happens, your veterinarian may need to adjust the dose or switch to another anti-seizure medication.

What Happens If a Dog Takes Too Much Phenobarbital?

If a dog takes too much phenobarbital, it can result in serious side effects including sedation, incoordination, low blood pressure, and slowed breathing. In severe cases, it can lead to coma and death. If you think your dog has ingested too much phenobarbital, contact your veterinarian or local emergency clinic immediately.

How Long Does Phenobarbital Ataxia Last?

Ataxia is a medical condition characterized by a loss of muscle coordination. Phenobarbital is a medication commonly used to treat seizures. However, phenobarbital can also cause ataxia as a side effect because of misuse.

The extent of ataxia caused by phenobarbital varies from dogs to dogs. Sometimes, ataxia may only last for a short period after starting the medication. For others, ataxia may be a long-term side effect.

There is no way to predict how each individual will be affected. If your dog is taking phenobarbital and experiences ataxia, it is important to talk to a vet about the best course of treatment. Sometimes, the ataxia may resolve on its own with time.

In other cases, the dose of phenobarbital may need to be adjusted or another medication may need to be added in order to control the ataxia symptoms.

How Long Can a Dog Live on Phenobarbital?

The half-life of phenobarbital in dogs is about 54-72 hours, so the concentration of the drug in your dog’s blood will be halved every 54-72 hours. This means that if you stop giving your dog phenobarbital, the concentration of the drug will slowly decrease over time. The recommended dosage of phenobarbital for dogs is 2-4 mg/kg body weight per day.

This means that a 50 kg (110 lb) dog would need 100-200 mg of phenobarbital per day. The exact dose should be determined by your veterinarian based on your dog’s individual needs. Phenobarbital is typically given twice daily, with the morning dose being slightly larger than the evening dose.

Phenobarbital is relatively safe and effective, but it is important to know how long your dog can safely take the medication. Typically, if your dog doesn’t show development of his seizure after 2 weeks, contact your vet. It can cause liver damage after prolonged use (over three months). (source)

If you miss a dose, give it as soon as possible and then return to your regular dosing schedule. Do not double up on doses or skip doses altogether, as this could be dangerous for your dog. It is important to monitor your dog closely while they are taking phenobarbital.

Side effects may include sedation, loss of appetite, increased thirst or urination, and dizziness or incoordination. These side effects are usually mild and resolve with time or with a reduction in dosage.

Signs of Phenobarbital Toxicity in Dogs

Phenobarbital is a barbiturate commonly used as an anticonvulsant and sedative in both humans and animals. In dogs, it is often used to control seizures. While Phenobarbital is generally safe, there is always the potential for side effects and toxicity, especially when used long term or at high doses.

Signs of Phenobarbital toxicity in dogs can include:

-Drowsiness or lethargy

-Ataxia (loss of coordination)

-Excessive urination or thirst

-Vomiting or diarrhea

Find Out Whether Other Things That Can Kill Your Dog


Phenobarbital is a commonly used drug to control seizures in dogs. Phenobarbital can be safe when used as directed, but it is important to be aware of the risks involved.

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