The approximate fraction of offspring with Irish spotting expected would be 1/4
For full pigmented dogs, the genotype would either be SS or Ss since S is dominant over s.
However, the two fully pigmented dogs gave birth to puppies with Irish spotting. Meaning that they are both heterozygous for the gene.
Thus:
Ss x Ss
SS Ss Ss ss
Offspring:
SS - fully pigmented - 1/4
Ss - fully pigmented - 1/2
ss - spotted - 1/4
Thus, the approximate fraction of the offspring with Irish spotting expected is 1/4.
More on monohybrid crossing can be found here: https://brainly.com/question/1185199