c1839 in (1909) 2 Feb. 4/4 [Melbourne Cricket Club decided to enclose the ground with a] four-rail, pig-proof fence.
1883 21 Sept. 12/2 The immense number of wild pigs makes cultivation impracticable without pig-proof fences.
1999 12 Apr. 106/1 I suppose it is good to know that Excedrin's packaging is not only childproof but also pigproof.