found two topics relate to your question:

How does the citizenship test affect whether someone qualifies as a dependent on my tax return?

To claim a dependent, you must meet five requirements. One of those requirements is the citizenship test, which requires that the dependent be a U.S. citizen or national, or a resident alien of the U.S., Canada or Mexico, for some part of the year.

If you are a U.S. citizen and you legally adopt a non-U.S. child who lives with you the entire year, the child qualifies as a citizen for this test.

Can I claim my elderly mother as a dependent on my income tax return, since I provide her with financial support?

If you supply a parent with financial support, you may be able to claim your mom or dad as a dependent on your income tax return and qualify for the same exemption you get for each of your own kids. However, both of the following must be true:

• His or her gross income must be less than $3,300 ($3,400 in 2007.)

• You provide more than one-half of the parent’s support for the year. Exceptions to this rule are made for "multiple-support" arrangements among siblings.

• You parent does not file a joint income tax return with someone else.

• Your parent is a U.S. citizen or resident of the U.S., Canada or Mexico.

The most difficult requirement to meet is usually the income test. To meet that requirement, you might be able to shift around your parent’s assets or make some other arrangement to get his or her income below the cap. Of course, that’s not a good idea if it would create a hardship or if it would simply force you to pay much more to meet the parent’s monthly living expenses.

so, from the above discussion, you sure can claim your parents who will be moving to canada.  in terms of sending money to them, you may incur the gift tax as some people have mentioned from above threads already.  it's a similar situation where you give the money to your kids as gift.