My dictionary has several translations for dog.

Some make sense to me such as:
erkek kurt - dog fox

But what is the difference between köpek and it?

Teşekkürler!

Can you give an example (non-vulgar) where it would be appropriate to use it ?

Bod, duda is right in her point. "it" is used for the dogs on the streets that you don't like. That's cur. But I wouldn't use "it" to describe a cowardly person. A cowardly person is cowardly. One can not describe them with the word "it". "it" is more likely has a vulgar, corse or low meaning. That word runs down the character or other qualities of a person and denigrates them. It's a blue streak kind of word. Nobody would like to be compared with a dog. Right? All those qualities are also same for the word "köpek" but the cur.

"it" is an insult word for the rough males. This word is also used to describe that a place is so dirty.

Examples to the usage;

1- Bugün it gibi çalıştım : Today I worked like a dog / Today I worked very hard.

2-it canlı : the one who tolerates any kind of trouble.

3-it derneği : the place where bandits take shelter and where is so dirty.

4-it kopuk : vulgar, worthless, impolite people.

All of these are slang. There isn't a phrase or a sentence that "it" is used as non-slangy. There are some other phrases for "it". Some are very bad phrases that's why I am not writing them here.

That's too much explanation for "it". Yea? hehe

Thanks!

But my question was not about when you would use it to describe people - it was when would you user it and not köpek to describe a dog (the four legged furry things!)

Although I think I get the idea of the difference