Pronominal adjectives of proximity/remoteness have two forms: pre and post, depending on how they are positioned in respect to the noun.
Acești câini sunt răi.
Câinii aceștia sunt răi.
When in post-position, the noun gains a definite article.
This ugly page is the only complete resource I could find online: http://limba-romana.ucoz.ro/index/pronumele_demonstrativ/0-159
Or you could explore this very comprehensive pdf (section 126.96.36.199 is relevant to your question): http://www.seelrc.org:8080/grammar/pdf/stand_alone_romanian.pdf