Definition of "bristling"

Tottenham had hoped to make a statement of real intent against the title pace-setters and while manager Harry Redknapp did not secure the victory he craved, he at least saw his side match United every stride of the way in a game that fizzled out after a bristling start.

2011 January 15, Phil McNulty, “Tottenham 0 - 0 Man Utd”, in BBC‎

When dogs fight, there are usually preliminaries to the actual combat — snarlings and bristlings and stiff-legged struttings. But White Fang learned to omit these preliminaries.

1906 May–October, Jack London, White Fang, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., published October 1906, part 3 (The Gods of the Wild), pages 144–145