Horses can have a heart murmur, so I would suspect they can have heart disease or other illnesses related to the heart. Aneurysm is a very real possibly and can strike quickly without warning. My first horse did have a significant heart murmur and the vet told me that there was a good chance that someday he would try to get up from laying down and just die. The day he died I found him in his stall, no thrashing or outward signs of distress. But he was also 38 years old.
Usually lightening victims have tell tale burn marks, especially on the feet. Horse shoes can actually come off as the metal in the nails melts. Leaving the melted nail in the hoof.
I would think EEE, West Nile or other similar diseases should have presented other symptoms before death.
Poisoning should have produced some neurological or medical symptoms before death.
Best wishes to this owner to come to some understanding of the loss of their horse.
Usually lightening victims have tell tale burn marks, especially on the feet. Horse shoes can actually come off as the metal in the nails melts. Leaving the melted nail in the hoof.
I would think EEE, West Nile or other similar diseases should have presented other symptoms before death.
Poisoning should have produced some neurological or medical symptoms before death.
Best wishes to this owner to come to some understanding of the loss of their horse.

