Did Evita and Tuco play together very much before Blondie came on the scene?

As I read your last post, I was saying to myself that I thought that is what was going on. If my other guess is correct, then I will say that Evita and Tuco did play together at least some times before Blondie came on the scene.

Border Collies (from what I have seen and heard about them) are very jealous dogs and very high energy and spirited. When they attach and bond they do so with 100% loyalty. They will protect what they believe to be "THEIRS".

I think perhaps someone who knows more about Borders can shed some more light on this aspect.

However, After reading your last post, I more than ever agree that this is dominance related. Unless you fear that one of the dogs will seriously get hurt, then you should let them work it out! If you think there may be blood shed then you can perhaps muzzle the dogs when you can't keep an eye on them.

Give them the space they need to work it out. If a violent confrontation occurs when you are around, intervien but treat both dogs equal. NO WINNER! Perhaps put them both in a time out or in a seperate room. This is where obedience training is very helpful.

If the fights do not become violent with blood shed then let them fight it out. You need to reinforce the winner. In addition you need to make sure you reinforce the winner in front of the loser. He gets petted first, get his food first and even gets to go outside first. You may not like Blondie getting beaten up but if he is the loser you can not sympathize with him.

I am working on this currently with my Dixie and Dusty. It is not easy to not sympathize with the loser. That is our natural reaction. However, you need to go against your natural reaction and reinforce what will feel like it is contradictory behavior from what you are feeling.

Perhaps Carrie has some other suggestions or corrections to my post. I am more of a trainer than a behaviorist.

As for the urination in the car - I would not take him in the car until this is addressed. Tuco probably feels less threatened in the car than anywhere since Blondie never goes for rides. Again, perhaps Carrie has more suggestions.

Keep your chin up. Things will get better.