They talk about Oleander soup for pets in this forum. I do not remember exactly where this is explained. I do remember, however, I followed Chris advise by seeking information about it. Please, search this. I would try it if I were you. I also love my dog very deeply and understand where are you coming from.
Sorry I do not have the complete and clear information. Did not expect some one with that concern in this forum. But I wanted to tell you the little I know. I am sure Christ or others will guide you better in this matter.