After reading through that thread, and seeing the pictures, I'd be willing to bet that head injury is more serious than what you might be thinking. If you look, the injury is right behind her sinus cavity. The bone is a bit thin there. Yes, horses can and DO have strokes.
Aside from the emergency exam, what else has your vet done as far as an examination? He should've had you bring in her in for films at the least, and given you antibiotics when he first saw her for the puncture wounds and such. Horses are very resilient, for the most part, and heal remarkably well even from bad injuries, as long as they're treated aggressively from the start.
I agree with everyone else, it's not a stupid dog, it's a stupid OWNER. Now, your brother in law's dog should meet up with my younger mare.....guarantee ya he won't be chasing horses any time soon...
. There were dogs at all the places she's been boarded at, all but one of 'em (my Hana when she'd visit) would want to chase the horses. Semmi would chase BACK. Lemme tell ya something, dogs will retreat REAL fast when 1000 pounds of equine fury is coming straight at 'em. To keep one boarder's dogs from chasing, whenever she came to visit her horse, or ride, we'd let Semmi out to wander the property, hehe. The dogs HID from her. Woman wouldn't listen about letting the dogs run loose as they were harassing all the horses, so...we FIXED that. After maybe three times of her dogs hiding from my girlie, she finally decided to leave them behind while going to the barn.