Phenobarbital may result in these side effects:
Anxiety.
Lethargy.
Sedation.
Increase in water intake.
Increase in appetite.
Increase in urination.
Anemia.
Weight gain.
Ataxia
Ataxia is when a dog loses coordination in his hind end or experiences weakness there. Phenobarbital can trigger ataxia, and if you notice this, you should let your vet know.
Causes of Cerebellar Ataxia in Dogs and Cats. In both humans and animals, the cerebellum is the area of the brain that controls coordination and movement. When this area is damaged, it can result in a loss of coordination, balance, and motor function control. It can also sometimes cause cognitive impairment.
Most of these side effects diminish or disappear after the first few weeks of therapy. Excessive urination, excessive thirst and excessive hunger are the most common long-term side effects.
Chronic or long term use (over 3 months) of Phenobarbital can lead to scarring in the liver and liver failure in a small percentage of dogs
To determine the correct dose of Phenobarbital, it can be very helpful to monitor its level in the blood. Your veterinarian will want to test Phenobarbital levels after approximately two weeks of therapy to be sure that your dog is in a therapeutic range. It takes two weeks for Phenobarbital to reach a steady state after starting or adjusting Phenobarbital.
Seizures are not uncommon in dogs, but many dogs have only a single seizure.
What is the prognosis of Epilepsy?
The prognosis for epilepsy is typically good although it is largely dependent on the number of seizures an animal suffers.
POTASSIUM BROMIDE AS AN ADD ON DRUG TO PHENOBARBITAL
Phenobarbital is what many veterinarians choose first when an anti-seizure drug is indicated for a dog. Phenobarbital has been successfully used in dogs for decades and has always been considered a relatively safe drug. Only recently has it been recognized that 20% of the dogs on Pb therapy develop liver dysfunction which can result in death if not properly treated. As a result, KBr is now becoming the first drug of choice for veterinarians. KBr and Pb are often used together to achieve control with dogs whose seizures are not well controlled by phenobarbital alone.
The use of potassium bromide appears to be relatively safe in dogs even when used over months or years and monitored correctly. Unlike PB, which is processed through the liver, KBr is broken down through the kidneys and does not have any known liver toxicity.
LINKS
http://www.canineepilepsy.co.uk/living-with-epileptic-pets.html
https://canna-pet.com/side-effects-phenobarbital-dogs
https://www.fitzpatrickreferrals.co.uk/neurology/epilepsy
http://www.canineepilepsy.co.uk
http://www.canine-epilepsy-guardian-angels.com/PbandLiver.htm
http://www.canine-epilepsy-guardian-angels.com/phenobarbital.htm
https://www.petforums.co.uk/threads/some-advice-needed-for-epileptic-archie.337028
https://en.wikipedia.org/wiki/Phenobarbital
https://www.weldricks.co.uk/products/phenobarbital-15mg-1-tablet
https://www.vetuk.co.uk/pet-meds-prescription-only-epiphen-c-21_726
