SLEEPY GRASS AND ITS EFFECT ON HORSES.

This study investigates the unexplained phenomenon of “sleepy grass” found in the Sacramento Mountains, which, when consumed by horses, allegedly puts them into a deep sleep without any usual symptoms of poisoning. This field research describes firsthand observations of horses’ behaviors and reactions after eating the grass, eventually concluding in the temporary lethargic effects it has on the animals.

Methodology and Observations

• The author recounts an expedition where they camped in an area abundant with “sleepy grass.” Upon feeding on this grass, the horses started showing signs of drowsiness and lethargy.
• A ranchman warned them of the stupor-inducing effect of the grass on horses that might last for a week.
• The horses were allowed to feed on the grass for half an hour before being moved to a different location and fed oats. They stayed away from the grass for the rest of the night.
• The following morning, one horse was found in deep slumber, while others also showed signs of fatigue.

Effects and Aftermath

• Despite their drowsy state, the horses were able to continue their journey, however, showing unusual signs of lethargy and sleepiness throughout the day.
• In another incident, when they camped in an area where “sleepy grass” was abundant, the horses fell asleep after feeding and were all found in the same state the next morning.
• The numbness lasted approximately three days, and was noticeable enough not to be mistaken for natural tiredness or sickness.
• After the effects of the grass wore off, the horses regained their typical energy and appetites, though they appeared gaunt, likely a result of their stint of reduced feeding during the stupor.

Grazing Preferences and Ranchmen Reports

• Notably, once the horses were exposed to and consumed the sleepy grass, they would avoid it afterward, even when it grew plentifully amidst other grazed grass species.
• Additionally, the horses consumed both ripe seeds and base leaves of the grass, although ranchmen believed it was the leaves that produced the somnolence.
• Cattle also avoided the grass, despite grazing nearby, but it was not reported if they were affected by it.

Identifying Sleepy Grass

• The species of grass affecting the horses was thought to be Stipa vaseyi, a.k.a, “sleepy grass,” but the research team did not present definitive proof that this was the grass in question.
• This phenomenon of “sleepy grass” has long been known within the area, although the specific characteristics that make this plant induce sleepiness in horses have yet to be determined scientifically.