Billys can come in pure and off-white, possibly with orange or with lemon spots on the head and body; their coat is short and smooth. They can weigh between 52–70 lbs and they stand around 60–70 cm at the shoulder for males and 58–62 cm for females. The Fédération Cynologique Internationale standard suggests the dog should gallop easily in its movement. The standard for the breed was established in 1886.
The Billy is not an apartment dog and needs a lot of exercise, like most large hounds they are difficult off the lead and extremely fast. They have been known to be same sex aggressive and do not always get along with other dogs, they are very intelligent and courageous, and have been used in obedience competition.
The Billy was created by Monsieur Gaston Hublot de Rivault in the 19th century, and was named after his home the Château de Billy, in Poitou. Billys we created by combining the three original strains of the Poitevin, the Montemboeuf, Ceris and Larrye. Whereas the modern Poitevin more closely resembles and the original Tri-coloured Larrye line, Rivault was more drawn to the paler colours associated with the Montemboeuf and Ceris lines, and colouration was a major determinant when selecting foundation stock. The pack was dispersed in 1927 and the breed almost faced extinction, only two hounds survived World War II, however de Rivault's son, Anthony, set about reviving the breed by judicious use of the Poitevin, the Porcelaine and the Harrier.