Rigwelted

Of sheep; overturned.

A heavily pregnant, broad backed ewe may roll over and be unable to right herself. She is rigwelted.

There is also a beer called Rigwelter due to the similar effect it is said to have on humans.

From http://www.farm-direct.co.uk/shared/glossary.html

 

Riggwelter Ale takes its name from a local Yorkshire Dales farming term which has Old Norse roots; “rygg” meaning back, and “velte” meaning to overturn. A sheep is said to be rigged or “rigwelted”, when it has rolled onto its back and is unable to get back up without assistance.

It seemed the perfect name for a strong beer from the Black Sheep Brewery in Yorkshire.

from http://www.blacksheepbrewery.com/beers/riggwelter_bottled_beer/