Colour-types
See Main Article Coat (dog)
Up to at least the seventeenth century bloodhounds were of all colours, but in modern times the colour range has become more restricted. The colours 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 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 5 alleles in the pattern-marking gene, producing variants from the red or saddle-less hound through three different types of progressively greater saddle marking to the ‘blanket’ type. However, more modern study attributes the variation to 3 different alleles of the Agouti gene. Ay produces the non saddle-marked "red" hound, As produces saddle-marking, and at produces the blanket or full-coat hound. Of these Ay is dominant, and at is recessive to the others. The interaction of these variants of the two genes produces the six basic types shown below.
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Black and tan, 'blanket' or full-coat type
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Liver and tan, 'blanket' or full-coat type
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Black and tan saddle type
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Liver and tan saddle type
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Red, black-pigmented type
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Red, liver-pigmented type
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