I have a 4 year Rott/lab mix that has been diagnosed with epilepsy within the last 2 years. The doctor has put him on Phenobarbital 64.8 mg 1 tablet two times a day, and valium when and if needed for his seizuress. He was good then for about 6 months, then after, he started seizuing again so we took him back for labs and to check his blood levels...they then changed his meds to the same 64.8 mg 1 1/2 two times a day, but also added K ProVet oral solution..my question pertains to longterm Phenobarbital usage, we have discovered little lumps on his body in different areas. One has grown and is now the size of a pea. Are any of these medications he is on, going to cause him cancer, I was told and have experienced certain medications that help with one thing and then cause worse problems in a another matter....could these little lumps be cancerous or just little cysts that arre fatty tissue, or do i have serious reason for concern at this point. He has only been on these meds within the laswt two years. But I am concerned and worried it is helping his seizures but slowly killing him in another way.