Dogs first seizure

Hello Vets, Question about dog’s first seizure I have an almost 8 year old mountain cur. I have had him since he was 11 months old, no health issues, weighs 40 lbs. regularly sees the vet. No other pets. he takes 40mg fluoxetine once daily and has for years for anxiety Tuesday was a regular day - he ate his usual food, drank his usual water, went out shortly and supervised in our fenced in yard, didn’t eat anything unusual or get into anything. Around 4pm, I heard a noise in the room he was sleeping in his bed in, and went in to find him rigid and unconscious on the floor near his bed. His eyes were open, dilated, and unresponsive. His legs straight out, neck extended, and head bent backwards. His mouth was closed tight and I couldn’t feel his heart or tell if he was breathing. He never lost control of his bladder or defecated. I got on the floor and put him on me, and called the vet. After about 4 minutes, his eyes began to respond to my voice and look around. But it was almost 10 minutes before he moved any of his legs or head. Then he acted completely normal and got up as if nothing happened. There had been no loud noises, nothing that could have stressed him out or scared him. He had been asleep. We went straight to the vet 15 minutes away. They drew blood for a senior panel and took a urine sample. The vet said they expected to find some issue with his liver, kidneys, or heart. All tests came back completely normal. No difference from the same bloodwork taken a little over a year ago. The vet said they have no other thoughts and just to watch him. I am concerned though as he never had one before, and had such a severe and long seizure. I have been hearing stories of owners going to work and coming home to find their dog dead from a seizure and I am scared to death to lose my best friend. Basically - in your expert opinion, where should I go from here? What could have caused him to have a seizure out of the blue? Should I be concerned about him having more? Thank you very much for your time.

Hello!   The first question is to figure out whether this was technically a seizure, or perhaps syncope (fainting), weakness or another neurological sign.  You have obviously had your dog to the vets so I suspect that they will have taken a good history and examined the patient; their thoughts on this are more to the point than mine are.  I will however draw a distinction that just because a blood test relating to the heart comes back normal, does not mean that the heart is normal (e.g. - depending on the test that has been done - certain biomarkers may suggest stretch within the heart muscle walls, but no blood test can tell you that a heart is normal).  Useful questions to ask your vets therefore include, 'What have you been able to rule in or out regarding the cause of this abnormal episode?' and 'Are there any more tests that need to be done.'  'How important is it that these tests are done / done now'.  'Is there anything we should be doing in the meantime.'   Hopefully the answers to these questions will result in an action plan relevant to your own pet, indicating the way forward.  Best of luck and please do let us know how you get on.