She was fine jumping, running the night before. Got up with me at 6 am as usual, but she had her head down, stumbled around like she was blind. before collasping and going into screaming seizures, (she never vocalized before, very quiet animal in her life). It was several hours before I could get her toan opened vet clinic, she was totally stiff in a semicoma. The vet said she was just old and it happens and I had to put her down. 11 years of love as my family member and recent years as a therapy dog , it haunts me that I don't know why it happen and if it can help someone else with my question by finding answer to this. He figures it was a stroke. She was 11 years old. no chemicals on her or in her or around her in her life time , all annual shots updated. Just why??