Seizure disorders are common in dogs and may have a variety of causes, including:
- epilepsy
- tumor
- infection
- trauma
- low blood sugar
- toxins or poisons
- hypothyroidism
- others
What is a Seizure?
Seizures in dogs are a neurological event.
- Generalized or grand-mal seizures are the most common type of seizure seen in dogs. Affected dogs lose consciousness with their body becoming stiff. The legs may move in paddling motions and the mouth may open and close in a snapping fashion. Urination and defection may occur while the dog is having a seizure also.
- Partial seizures may occur and involve activity in a specific area of the body. These types of seizures may progress to generalized seizures.
What is Epilepsy?
Seizure disorders in dogs are referred to as epilepsy when no cause for the seizures can be found. Epilepsy in dogs is a very common diagnosis.
Phenobarbital as Treatment for Seizures and Epilepsy in Dogs
Phenobarbital is commonly considered to the first drug of choice for treating seizures and epilepsy in dogs. The goal of administering phenobarbital is to suppress the seizure activity.
Phenobarbital is an oral medication which is readily available through your veterinarian or through a pharmacy.
Treatment with phenobarbital in dogs should be started:
- when single seizures occur more often than once monthly
- when clusters of seizures occur, with one seizure immediately following another
- when status epilepticus (a seizure which does not stop without medical intervention) occurs
Successfully suppressing seizures has been found to be more difficult in some breeds of dog, such as German Shephard Dogs, Golden Retrievers, Irish Setters and Saint Bernards. In these breeds, some veterinarians may prefer to begin treatment with phenobarbital even if seizure activity is minimal.
What is Expected when a Dog is Receiving Phenobarbital?
Though phenobarbital is quite effective in suppressing seizures in dogs, break-through seizures can happen even while receiving phenobarbital. Generally, though the seizures may be difficult to watch, there is little danger for the dog in experiencing occasional mild seizures such as those which normally occur in dogs receiving phenobarbital.
Medical attention should be sought immediately if your dog:
- has a seizure which continues without stopping for 5 minutes of longer.
- has more than three seizures within a 24 hour period.
Side effects frequently seen with phenobarbital in dogs include:
- sedation, which usually resolves as the dog acclimates to the phenobarbital
- excessive thirst
- excessive urination
- increased appetite
- anemia, which is rare but may require discontinuation of phenobarbital administration
- liver failure
Monitoring Phenobarbital Administration for Dogs
Your veterinarian will need to monitor the levels of phenobarbital in your dog's blood to make certain your dog is receiving an adequate dosage of phenobarbital. Blood phenobarbital levels usually need to be checked about 2 to 4 weeks after beginning a phenobarbital dosage regimen or changing a phenobarbital dosing regimen. Once your dog's blood tests show that therapeutic levels of phenobarbital are being administered, it is normally advisable to have the phenobarbital blood level checked every 6 to 12 months, assuming the seizures are well controlled.
In addition to phenobarbital blood levels, liver enzymes and other liver function tests, such as bilirubin and/or bile acids, will need to be monitored periodically to be certain the phenobarbital is not adversely affecting your dog's liver. It is not unusual however to see mildly to moderately elevated liver enzyme levels when your dog is receiving phenobarbital. This is because phenobarbital acts to induce metabolic enzyme production. However, if the liver enzymes become severely elevated, or it there are alterations in bilirubin or bile acid levels in your dog's blood, your veterinarian may counsel you to decrease or discontinue the phenobarbital and add another anticonvulsant medication, such as potassium bromide, to your dog's treatment regimen for seizures or epilepsy.
Phenobarbital can react with many other medications, so make certain you advise your veterinarian of any other medications your dog is receiving.
Phenobarbital should be given as directed by your veterinarian and you should try not to miss any doses. Doing so could trigger seizure activity which could be quite serious for your dog. In addition, phenobarbital should not be discontinued suddenly.
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