How do I get two dogs to get along with one another?

I have a total of four dogs in my home. Two of them just don't like one another and can't get along with each other. The smallest and the largest. For the most part, they all get along with one another. The largest of the four likes playing with the two medium ones. The smallest likes to play with the two medium ones. I don't know what to do but to keep the two separated. Please help!!! There must be a way for these two dogs to start getting along with each other.

Asked by Member 1091282 on Feb 10th 2012 in Aggression