How does epistasis explain the coat color in a labrador retriever?

Epistasis explains coat color in Labrador Retrievers through interactions between different genes. Specifically, two genes are involved: one gene determines the pigment (black or brown), while another gene (the E gene) controls whether the pigment is expressed. If a dog has two recessive alleles for the E gene (ee), it will be yellow, regardless of the alleles for the pigment gene. Thus, the presence or absence of the E gene masks the effect of the pigment gene, illustrating epistasis in action.