In humans, the conversion of ALA is inefficient but sufficient for healthy people. That is why flax seed oil can be used as a source of Omega-3 for most people.
One author, Dunbar, says dogs can convert ALA to EPA and DHA. Usually the ALA quantity far exceeds the needed EPA and DHA, so it is possible that even a small percentage of conversion can be enough EPA and DHA for good health.
I really don't know so for breeding females I certainly add fish oil.