Grass sickness, alternatively termed equine dysautonomia, is a rare but predominantly fatal illness in horses.
[1] The majority of visible clinical signs are related to paralysis within the digestive tract although nerve damage occurs throughout the body.
There are three forms of grass sickness: Clinical signs common to all subsets include: depression, anorexia, colic (moderate with AGS/SAGS and mild with CGS), paralysis of the intestines, excess salivation, constipation, nasogastric fluid secretion, patchy sweating, muscle tremors and eyelid drooping.
[3] The Dick Vet research finally isolated a neurotoxic enzyme similar to the snake venom and discovered it as the probable cause of the sickness.
Differential diagnoses for grass sickness are varied and include any other cause of colic and weight loss, tying-up, laminitis, botulism, choke and dental problems.