The Yorkshire Terrier is one of the smallest dog breed of terrier type, and of any dog breed. The breed developed during the 19th century in Yorkshire, England. It is very rare to get a particolour, and if one is found, it tends to be very expensive. Some Yorkshire Terriers are solid golden, they only produce pheomelanin, others are liver or chocolate, a brown colour; they produce brown eumelanin instead of black eumelanin. The standard prescribes clearly defined fur-colors, and non-standard colours may indicate crossbreeding with other breeds or in rare cases even health problems.