Bloodhound

The bloodhound is a large scent hound, originally bred for hunting deer, wild boar, rabbits, and since the Middle Ages, for tracking people. Believed to be descended from hounds once kept at the Abbey of Saint-Hubert, Belgium, in French it is called le chien de Saint-Hubert.

This breed is famed for its ability to discern human scent over great distances, even days later. Its extraordinarily keen sense of smell is combined with a strong and tenacious tracking instinct, producing the ideal scent hound. It is used by police and law enforcement all over the world to track escaped prisoners, missing people, and lost pets.

Bloodhounds weigh from 36 to 72 kg (80 to 160 lbs). They are 58 to 70 cm (23 to 27 inches) tall at the withers. According to the AKC standard for the breed, larger dogs are preferred by conformation judges. Acceptable colors for bloodhounds are black, liver, and red. Bloodhounds possess an unusually large skeletal structure with most of their weight concentrated in their bones, which are very thick for their length. The coat, typical for a scent hound, is hard and composed of fur alone, with no admixture of hair.

This breed is reported to be gentle and is tireless when following a scent. Because of its strong tracking instinct, it can be willful and somewhat difficult to obedience train and handle on a leash. Bloodhounds are known to have an affectionate and even-tempered nature to humans, and are considered to be excellent family pets.

Up to at least the 17th century, Bloodhounds were of all colors, but in modern times the colours range has become more restricted. The colors are usually listed as black and tan, liver and tan, and red. White is not uncommon on the chest and sometimes appears on the feet. Genetically, the main types are determined by the action of two genes, found in many species. One produces an alternation between black and brown (liver). If a hound inherits the black allele (variant) from either parent, it has a black nose, eye rims, and paw pads, and if it has a saddle, it is black. The other allele suppresses black pigment and is recessive, so it must be inherited from both parents. It produces liver noses, eye rims, paw pads, and saddles.

The second gene determines the coat pattern. It can produce animals with no saddle (essentially all-tan, but called 'red' in Bloodhounds), ones with saddle-marking, or ones largely covered with darker (black or liver) pigment, except for tan lips, eyebrows, forechest, and lower legs. These last are sometimes referred to as 'blanket' or 'full-coat' types. In a pioneering study in 1969, Dennis Piper suggested five alleles in the pattern-marking gene, producing variants from the red or saddleless hound through three different types of progressively greater saddle marking to the 'blanket' type. However, more modern study attributes the variation to three different alleles of the agouti gene. A^y produces the non saddle-marked "red" hound, A^s produces saddle-marking, and a^t produces the blanket or full-coated hound. Of these A^y is dominant, and a^t is recessive to the others. The interaction of these variants of the two genes produces the six basic types shown below.

Another source does not recognise a^s as a separate variant. Instead, it says "a^t includes tan point and saddle tan, both of which look tan point at birth. Modifier genes in saddle tan puppies cause a gradual reduction of the black area until the saddle tan pattern is achieved." 'Tan point' refers to the blanket type from the typical tan eyebrows, muzzle, and socks.

It is likely that a third gene determines whether or not there is a melanistic mask. E^m, the allele for a mask, is dominant over E, the allele for no mask.