an informal name for the Scots pint, a unit of volume equal to about 1.80 U.S. liquid quarts or 1.70 liters. Specifically, the jug of Stirling is the actual vessel (on display at the Stirling Museum) which was the legal standard for Scottish volume measurements prior to the introduction of the British Imperial units.
A jug is a type of container for liquid. It has an opening, often narrow, from which to pour or drink, and nearly always has some kind of handle. One could imagine a jug being made from nearly any watertight material, but most jugs throughout history have been made from clay, glass, or plastic.
The Jug is not a purebred dog. It is a cross between the Jack Russell Terrier and the Pug. The best way to determine the temperament of a mixed breed is to look up all breeds in the cross and know you can get any combination of any of the characteristics found in either breed.