You need to get some dextrose down her neck as soon as possible. Anything which will give her an energy boost. 'Lectade' was always the thing to have around, pre-lambing, but Lucosade or Irn Bru would probably help her out. A straight glucose solution @ 2oz to half pint of warm water will help. For a rapid response, intravenous injection of solution is recommended.
Preg Tox in ewes is due to a number of metabolic disorders which can be triggered by a period of bad weather, shortage of appropriate feed, lack of water in hard weather. Ewes which are too fat early in their pregnancy are particularly susceptible to PT.
The normal metabolic routine is disrupted and a rapid build-up of toxins in the ewe's system is the result. Affected ewes become unresponsive to stimuli, seemingly oblivious to the presence of the shepherd, and unable to get around; they seem to be visually impaired, with widely-dilated pupils and, if got to their feet, they may stagger around with a high-stepping gait, and just want to lie down.
Acetonaemia may be one of the complications, and the characteristic 'pear-drop' scented breath and urine will confirm this.