Lady has been on Phenobarbital for ten years. She also gets a monthly heartworm pill with no problems. Lady has been on multiple medications along with her seizure medication per her vet with no side effects. The only thing you really have to watch is medication that makes them drowsy as Phenobarbital already is sedating. Lady takes Zyrtec for allergies as other veterinary antihistamines and Benadryl make her "drunk".
I would not want to take a chance on heartworms as the treatment itself can be so dangerous.
Make sure you use Interceptor for heartworm prevention, not Heartguard. Heartguard/Ivermectin has been shown to lower the seizure threshold in some dogs.
Are you giving Diego milk thistle/Marin to protect his liver from Phenobarbital? Pheno will destroy his liver over time. I have been giving Lady milk thistle practically from day one. She showed signs of liver damage (ALT 300) a few years ago. I added Denosyl and now homecook a liver diet for her and her ALT is back down to 79. My vet is amazed that a dog who has been on Pheno for over ten years has normal liver values.
