In response to this article in the Guardian I wrote this response which might be usefully re-posted here
when Jesus effectively calls a gentile woman a dog, we can try to imagine that he was smiling ironically, mocking the Jewish xenophobia of his day
Funnily enough I was meditating about this passage in the New Jerusalem Bible(Matthew 15:21-39) earlier this week. It was Monday in a pleasant little park between Torquay railway station and the waterfront to be precise (a little information to help future hagiographers there). Some of my thoughts might be relevant here.
The episode reminded me of the earlier event at Cana in Galilee where our Lord responded to our Lady's prayer "they have no wine" by saying My hour has not come yet and then going ahead and changing water into wine thus inaugurating His public ministry in response to His blessed mother's prayer. Here Jesus responds to the Canaanite woman's plea 'Lord, Son of David, take pity on me.' by saying I was sent only to the lost sheep of the House of Israel. As before He is laying out His game plan. He is the fulfilment of the Mosaic Law therefore His religious mission is only directly relevant to those people who embrace the Law or are embraced by it. Once the Law is fulfilled it becomes universal until then it is particular.
Undeterred the woman says 'Lord help me' which leads to the famous retort It is not fair to take the children's food and throw it to little dogs. Let us be clear. The Law points to a community which is pure and an outside world which is impure, unclean. Our Lord is correctly restating that perspective. The things of the world are at enmity with the things of God and the community of the Law was a visible (and deeply flawed) image of the purity of God in relation to which the world was an image (profoundly accurate) of those things and people which are impure. It would be an affront to give what is pure to those who would make it impure simply by touching it. First the receiver of the gift must be purified and then the gift can be given. And gentiles could only be purified by being washed in the Blood of the Lamb not yet shed at this point.
Once more the woman was undeterred. 'Ah yes, Lord; but even little dogs eat the scraps that fall from their masters' table.' Her persistence in prayer, her faith and the compassion of Jesus combine to produce the desired and expected result her daughter is cured. The cure consists of having a demon cast out of her which is symbolic in itself but I shall not dwell on that in this context. Now we have the next resonance with the Cana episode. After turning the water into wine there was no looking back. Our Lord went on to the full flowering of His Galilean ministry. After healing the Canaanite woman He goes on deeper into gentile territory.
29 Jesus went on from there and reached the shores of the Lake of Galilee, and he went up onto the mountain. He took his seat, 30 and large crowds came to him bringing the lame, the crippled, the blind, the dumb and many others; these they put down at his feet, and he cured them.
Proceeding from Tyre and Sidon, Gentile country, He goes over the mountains into the gentile lands at the top of the Sea of Tiberias. It is significant that throughout the Gospels when He heals like this He is also described as preaching and teaching but here He simply confines Himself to healing as teaching would not be appropriate here. Even so His audience recognises what is going on
31 The crowds were astonished to see the dumb speaking, the cripples whole again, the lame walking and the blind with their sight, and they praised the God of Israel.
When Jewish crowds praise God it is simply said "they praised God". Here it is said "they praised the God of Israel" to make clear that it was not their own tribal or local God they were praising but that of the charismatic Jewish healer in their midst. He goes on to perform His second feeding miracle and afterwards seven baskets of scraps are collected. I am told that the Greek word used for basket here is different to the one used for the earlier feeding of five thousand event. One word was used for the kind of baskets peculiar to the Jews and another for that peculiar to Gentiles. However that might be the numbers have significance. Twelve baskets are collected at the Jewish event and twelve is a number signifying the tribes of Israel. Seven baskets are collected at the gentile event and, as I have written elsewhere, seven is a number signifying fullness, completeness and signify's here that the gentiles will eventually form part of the completeness of the people of God.
So the disparaging reference to "dogs" at the beginning of this sequence is merely the trigger for a sequence of events displaying the power of prayer and the compassion of Jesus. 
