Emergency Care for Accidental Overdose

By: Dr. Warren Riggle

Through the years, I have seen many dogs who have not used good judgment about what they eat. It is so easy for accidents to happen. Mandy, a 9 ½ year old very beloved lab mix, came in to Animal Hospital of North Asheville in the evening of June 4, 2012 as an emergency. Mandy had found a bottle of Phenobarbital tablets that had just been purchased at the drug store for Mindy, one of the other dogs in the family. Mindy takes the human drug Phenobarbital to help prevent seizures. She has been taking Phenobarbital for many years and it has been very helpful to her in preventing seizures. Since Mindy has been on the drug so long, we have prescribed large quantities of Phenobarbital at a time so her owners don’t have to make as many trips to the pharmacy. Unfortunately, Mandy found the bottle on the counter, got the bottle open by chewing it and ate all 360 of the 16.2 mg Phenobarbital tablets that were in the new, unopened bottle. The average dosage of Phenobarbital for a dog Mandy’s size would be 4 tablets twice daily. Mandy had eaten a ninety times overdose! Symptoms of over dosage of Phenobarbital are ataxia (drunk acting), lethargy, sedation, recumbency (inability to stand), depression, hypothermia (decreased temperature), coma, and death. In addition, there is also a concern for damage to the liver. By the time Mandy arrived at the Animal Hospital, she already could barely stand, even though the owners had seen her eat the tablets and had brought her in immediately.

At Animal Hospital of North Asheville, we are very fortunate to have access to consultants who are available 24 hours a day 7 days a week at a Pet Poison Hotline. They can inform us of the most up-to-date treatments for specific toxicities. I consulted with them immediately, and the poison control hotline veterinarian on duty recommended that we induce vomiting (which we had already done), and then give intravenous fluids, anesthesia to allow the stomach to be lavaged with a stomach tube, followed by giving activated charcoal via the stomach tube.  When dogs have eaten something they should not eat, we can give apomorphine, a drug that is given intravenously to induce vomiting. Fortunately, apomorphine almost always causes a dog to vomit multiple times. Time is of the essence when we’re giving apomorphine to dogs who have eaten medications or toxins, since the longer the material is in the stomach, the more of it is absorbed. Mandy vomited up a lot of food with the Phenobarbital tablets that were already dissolved. There was not any way to estimate how much of the Phenobarbital that she had ingested by looking at the multiple vomiting episodes, so we knew we needed to treat her for potential over dosage. We placed an IV catheter when she arrived and she immediately began receiving intravenous fluids.

Once we had induced vomiting and started IV fluids, Mandy was given intravenous propofol for anesthesia. I placed a large stomach tube into Mandy’s stomach and flushed the stomach multiple times (this is also known as “pumping the stomach”).  After the stomach had been thoroughly lavaged, 400 cc (27 tablespoons) of activated charcoal was placed in the stomach through the stomach tube. The flushing of the stomach was helpful to remove more of the Phenobarbital. The activated charcoal acts as a “sink” for the Phenobarbital, pulling it from the blood vessels back into the intestine where it can bind to the charcoal.

The first 8-10 hours were the most critical for Mandy. We have all night care for our patients with a veterinary nurse who can call the doctor at anytime during the night if there are concerns. Her vital signs were monitored very closely with a Surgivet unit that continually monitored Mandy’s blood pressure, electrocardiogram, and blood oxygen levels. Her temperature was frequently taken to be sure she was maintaining her normal body temperature, and her respirations were observed closely. We were prepared to breathe for Mandy if she stopped being able to breathe adequately on her own. This would mean placing an endotracheal tube, putting her on oxygen, and helping her breathe with assistance. Mandy was kept on continuous IV Lactated Ringers Solution which kept her hydrated and helped her body eliminate the Phenobarbital.

Mandy remained very sedated all night and yet we were happy her vital signs remained stable. She was unaware of her surroundings throughout the night. By morning, Mandy was slightly aware and was able to raise her head a small amount.  She stayed sedated the entire next day and through the night.  Her vital signs remained stable. Early the next morning, I was thrilled to see that Mandy was able to stand for the first time and walk a few steps, though she was very wobbly.

Through the day, she was still very wobbly, but continued to improve. We performed a comprehensive blood profile and complete blood count to make sure her organ functions were remaining stable. Thankfully, Mandy’s liver and kidney tests along with her other blood tests were normal when we sent her home in the evening of June 6, 2012. It took Mandy several more days to get back to normal, but she’s doing fine now. We are all thankful we could administer the emergency care that Mandy needed to save her life and that she has continued to do so well.

Comments

My dog Spanky is at the emergency vet right now after ingesting 80x the dosage for a dog his size. He too stole my other dogs meds. It sounds like this dog survived, which is hopeful for us. It sounds like he is getting similar care and to expect a few days or weeks of recovery. Thanks.

Jody, we are so very sorry to hear about Spanky. We don’t believe that Spanky is an AHNA patient, but we are so glad that you found our blog. You have our sympathy as we know how agonizing this time is. We certainly are pulling for him to make a full recovery! Please let us know by emailing info@ahna.net.

My dog Thor just did the same thing - 2.7 grams of phenobarbital. He is a 80lb shepherd/border collie mix and is 6 years old in good health. He is on supportive therapy but unfortunately we couldn't get him to vomit when he was brought into the vets (still conscious) but he did get charcoal. He eventually lost consciousness and remained that way for 24 hrs. He now has moments of consciousness and even gets into sternal recumbency occasionally. However, he is having periods of thrashing and paddling and is being given diazepam when this happens. However now (48 hrs later) the diazepam is not working as well and the vets are talking about acepromazine. Is this thrashing/paddling a true seizure or a reaction to hallucinations and panic (it sometimes stops when he hears calm voice talking to him)? I'm not comfortable with doping him on top of his overdose so your opinion would be welcome.

Hi Laura,

We are so sorry to hear about Thor. Please call us at 828 253 3393 - we don't give this kind of advice on the internet, but would be happy to talk to you.

I just came across this blog as I can't sleep after taking my dog Chip to the emergency vet nearby. My wife and I went to visit our new niece that was born yesterday and returned home 7 hours later to our dog Chip (a 6 year old cocker spaniel) who could walk but was stumbling all over the place like he was drunk especially on the tile.

A few minutes later we found his plastic pill case completely empty which he had gotten into while were gone. My wife had just loaded it with a 2 week supply (28 pills) of phenobarbital and he ate every single one of them. She left it fully loaded for the past 3-4 years next to our bed and he never touched it. But the difference this time is she just bought new peanut butter pill pockets to put them in (vs. the old beef pill pockets) and he apparently couldn't resist the new smell.

He's at the emergency vet now and they were cautiously optimistic but didn't give us any real answers of how they think he'll end up. The really scary part is they made him vomit and didnt see any trace of the pills so they had already all entered his system.

This blog gives us at least some hope that he will turn out ok. Thanks for sharing the story.

Hello Matt,

We are so sorry to hear that this has happened to Chip. You must be devastated. Thank you for writing in and sharing. We are hoping for the best for Chip. If you are able to, please let us know how Chip is doing.

Our Best Wishes -
The AHNA staff

Last night my 6 month old shep/lab puppy ate approximately 27 tablets of prevacox that my older dog takes for arthritis. We induced vomitting with hydrogen peroxide. She looks fine today yet is obviously still not herself, with questionable blood in her urine this morning. Should I be concerned about any complications including hepatoxicity or kidney damage?

I have been the primary caregiver for our dog who was given phenobarbitol for seizures last Friday at the ER. The Doctor gave him an IV of phenobarbitol to give a quick load, then sent him home with 16.2mg to be given at home. The bottle stated give two tabs at 8am, then 1 tab every 12 hours after. My husband has given her one each morning but accidentally gave her two yesterday morning, one last night and two more this morning. Do I give him one tonight or no?

Hello -

Anytime you have an urgent question that needs to be answered about your pet's drugs, please call us. If we are not open, then call the Pet Poison Hotline: 1-800-213-6680

We hope that your dog is well.

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