Hello, I'm Dr. Deb and will do my best to help you today.
I just recently came online and see that your question hasn't been answered. I'm sorry for the delay but if you'd still like a reply, I'd be happy to provide one.
I'm sorry that your lab has been diagnosed with a brain mass. I understand that every vet practices differently (and this isn't a question that you've asked about) but in my experience, Keppra or Zonisamide tend to work somewhat better at controlling seizures secondary to a brain mass as opposed to Phenobarbitol or even Potassium Bromide. This may be something to discuss with your vet.
But, to address your specify question, there shouldn't be any contraindications to giving your lab the herbal remedy that you've mentioned.
I'll often suggest Vet Select Nuroplex (Seizure) Formula for my patients although, in all honesty, these products may not be efficacious since controlled studies haven't been done on them.
The following is what I also suggest for my patients which may help to reduce the frequency and/or severity of seizure activity:
1. Magnesiumoxide (not citrate or chloride) at a dose of 200mg/day. Some forms may cause diarrhea; just reduce the dose should this happen.
2. Taurine at a dose of 500mg- 1 gm/day
3. Melatonin at a dose of 1-5mg at night Just double check the label and avoid those with Xylitol since ingredient this can be toxic to dogs.
4. Vitamin B6. Purchase B -50 multiple B- vitamins and give 1/2 day
5. Medium chain triglycerides (unprocessed coconut oil) 1 tsp/day but it should be the unprocessed type
6.Vitamin E 200 IU/day
7.Omega 3 fatty acids
8. SAMe (S-adenosyl-methioine) at a dose of 10 mg/lb once daily
I hope this helps although, again, my apologies for the delayed reply. Deb