Phenobarbital For Dogs: Uses, Dosage, & Side Effects

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Phenobarbital is one of the most commonly used drugs to treat epilepsy and other seizure disorders in dogs. It is also known by the brand names Luminal and Barbita. Phenobarbital works by decreasing and stabilizing neuron activity in the brain. It increases the neurotransmitter GABA, which calms nerves, and decreases glutamate, which is a neurotransmitter that stimulates nerves. While this decreases seizures in dogs, it can also lead to some unintended side effects, such as lethargy and sedation. Phenobarbital is not approved by the FDA for veterinary use, and it is a controlled substance, so it is only available via prescription from a DEA-licensed veterinarian. If your vet prescribes phenobarbital for your dog, follow their instructions for dosage closely. Here is what you should know about the uses, dosage, and side effects of phenobarbital for dogs.

Uses Of Phenobarbital For Dogs

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Phenobarbital is primarily used to treat seizure disorders such as epilepsy in dogs. Diazepam, more commonly known as Valium, is another anticonvulsant drug that is sometimes prescribed to dogs for seizures. There are other drugs available that have fewer side effects, though they are more expensive. Phenobarbital is one of the most commonly used drugs to treat seizures in dogs because it is so effective and inexpensive compared to other options. Occasionally phenobarbital has been used as a sedative, as well.

Dosage Of Phenobarbital For Dogs

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The usual dosage of phenobarbital for dogs depends on body weight and individual response to the medication, and the absorption of the drug varies among breeds, so veterinary instructions must be strictly followed. Typically, the starting dosage for dogs is 1 to 2 mg per pound of body weight given twice daily. This can be increased up to 8 mg per pound of body weight per day based on the dog’s response. It is important to continue giving the drug to your dog for the full duration of the prescription and not miss a dose, as this can result in seizures. Overdose can result in nervous system depression.

Phenobarbital is often provided in doses that are measured in “grains” rather than milligrams. One grain is equal to about 60 mg, and the drug is available in 1/4 grain, 1/2 grain, 1 grain, and 100 mg tablets. It is also available in an injectable form, which comes in 65 mg/ml and 130 mg/ml doses. Your veterinarian will give you instructions on how to properly give your dog the correct amount of phenobarbital to treat the seizures.

Side Effects Of Phenobarbital For Dogs

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Phenobarbital is generally safe for dogs when prescribed in the correct dosage, however there are some short-term and long-term side effects that may occur. Short-term side effects typically clear up in a few weeks, and your veterinarian will have to monitor your dog for long-term side effects if they are exposed to the drug for an extended period of time. Here are some of the common side effects seen in dogs that take phenobarbital.

  • Lethargy
  • Sedation
  • Anxiety
  • Restlessness
  • Loss of coordination
  • Increased thirst or appetite
  • Weight gain
  • Increased urination
  • Anemia
  • Liver damage (long-term use)

If you see concerning side effects of phenobarbital in your dog, consult your veterinarian, as they may wish to alter the dosage or seek an alternative form of treatment. Dogs with Addison’s disease, kidney disease, respiratory problems, or existing liver disease should not be given this drug. Make sure your veterinarian is aware of any medical conditions your dog has, as well as any other medications your dog may be taking, as these can react poorly with phenobarbital. As with almost all drugs, there is a risk of allergic reaction that can lead to anaphylaxis, a life-threatening condition. Contact your veterinarian right away if your dog has trouble breathing, starts sneezing, breaks out in hives, or shows other allergy symptoms.

Has your dog ever taken phenobarbital? Did it help with their seizures? Let us know in the comments below!

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