Yes, when a definite noun has an adjective, we normally need the article in front of it too. den vita hunden in the singular, de vita hundarna in the plural. This is called double or triple definiteness, since the definiteness shows on the article, on the adjective, and on the noun.
One notable exception from that rule is things that behave more or less like names. Like Vita Huset, 'the White House', if you're talking about the famous one – it's like a name, so we skip the article.