Vestibular disease and Stroke. Please help!

[quekong]

I have a 13.5 year old basenji. During the last a month and 20 days, he had three episodes of vestibular syndrome. I took him to ER few times and we have seen two neurologists since, one was at San Francisco and one was at UC Davis Vet. Many testing include MRI, spinal tap, X-rays, Ultrasound, blood work, urine analysis, urine culture and so on had been done. Most tests came back normal or with very minor issues. The MRI indicate there are places of infarcs and hemorrhages. Both neurologist has seen these MRI problems, first neurologist thought these are old infarcs that she didn't believe those are causing his vestibular syndrome, she expects my dog to have a full recovery. The second neurologist at UC Davis thinks these are got to be strokes because this has happened three times already in such short time. He thinks there is an underlying reason that is causing my dog to have these episodes. He ordered additional tests which mostly also came back normal. I am still waiting on two more tests result. The doctor thinks it annoys him that he could not find anything wrong that he thinks that maybe causing these strokes or vestibular episodes.

I am a foreigner myself to the U.S., it makes even harder with the language barrier. I am asking here to see if anyone can think of anything that would be able to help finding the underlying reason that is causing my dog to have these episodes. I am really afraid of another one and I know my dog is as well. I can tell on his face. It is as difficult enough right now for him, if another episode comes I really don't know what to do. If you know about this problem, please email me. I will provide you with more details. Thank you so much. Please help. My dog's name is Chester. My email is quekong@aol.com. I thank you from the bottom of my heart.