Chihuahuas come in two coat varieties, smooth and long. The inheritance of the genes responsible for which coat will be expressed can be interpreted using a simple punit square. The Smooth Coat is the dominant gene in the chihuahua and will mask the Long Coat gene in a heterozygous animal. The Long Coat gene is homozygous recessive; the animal must be homozygous (LL) in order for the gene to be expressed.