Spot came to see us as an emergency one weekend because he had
suddenly gone blind and was showing neurological abnormalities.
Once Dr. Beaumont performed her examination, she could see abnormal
changes in his retinas. At this point, Dr. Beaumont thought that
Spot's acute onset of blindness might be caused by an infectious
disease or an auto-immune issue. We re-examined him 2 days later
and his vision and neurological abnormalities were much improved,
but we didn't expect him to improve so much so quickly. A few days
later we learned that Spot's owners had dewormed over 20 horses
with ivermectin the day before he started showing symptoms. Spot
has a history of eating horse feces and his symptoms were not the
typical signs of an auto-immune disorder or an infectious disease.
We rechecked Spot again 1 week later and he was completely back to
normal! He had regained all of his vision and was acting like his
normal self! We were able to rule out an infectious disease and
auto-immune disorder based on bloodwork and his rapid improvement.
Spot's temporary blindness and neurologic symptoms were most likely
due to ivermectin toxicity (from eating horse feces after the
horses had been dewormed). Spot is doing great and is back to
helping his owners take care of the ranch.