So my husband had found this dog at his work a few days ago. Helooks like a bordercollie mix. We already have two dogs, a cocker spaniel, and a jackrussell/lahaso apso. The jack/lahaso is only a year old and loves to play with other dogs, so the new dog and the little one get along fine. But my cocker spaniel will not so much as try to really get a long with the new dog. THe new dog is very sweet and nice to the other dogs and has never growled or bitten, but my cocker spaniel growls and snaps at the new dog every time he even comes slightly close to him. He's not hurting him and is probably just showing him "get away from me" or "I'm the boss" so he hasn't attacked. At first they got a long and were playing a little, but then now the cocker spaniel is being mean. This is how the cocker spaniel acted when we brought home the jackrussell, but he got over it in a day or two. Are there any ways I can help them get a long? They play just fine at the dog park when there are other dogs there. Any tips/advice? Or will time only tell?

Sounds like the cocker spaniel is a bit jealous of the new dog. Make sure that he still knows the position he holds in your family. In the wild dogs live in packs with definite Alpha's, he's probably insecure about his position and wants to assert himself with his new pack member. I'm not an expert, just a dog owner who has been there, done that. Give them time and lots of assurance, things should work their way out.