Not trying to be a D, but I have to correct this...
Co-dominant means that the heterozygous form is visible in animals that carry the gene; and that the homozygous form is also visible but produces a different appearance than the heterozygous form.
Dominant means that the allele produces the same visible phenotype whether heterozygous, or homozygous.
Recessive means that the gene produces a visible phenotype only in homozygous form, and (in most cases) is invisible in the heterozygous form.