Utilizing REGEX pattern:
[^?!.\s][^?!.]*?\b([Cc]at|[Dd]og|[Bb]ird)\b[^?!.]*[.?!]
to match an entire sentence with the above-included words, even if the sentence spans multiple lines.
However, I've found that if the word of interest is the first in the sentence, it will not match.
For example: The bird is dead. Will Match. Dog days are over. Will Not. Often the sentences I'm looking for are incomplete grammatically as the second listed, but follow a beginning capitalization and followed by period structure.