Introducing a puppy to an Older dog

[CodyCleo]

I recently adopted a 1 year old puppy and slowly introduced her to my 11 year old Border Collie Mix.  After about 2 weeks of using leashes and a baby gate, they began playing and looking like the best of friends.  We had company and my older dog became jealous and attacked the puppy.  No damage was done but alot of noise and slobber.  My kids are very upset about this and now my older dog is showing aggression.  We love this new puppy and want this to work very badly but we are all very shaken up.  I don't want the puppy to be harmed or these fights to persist.  Any suggestions?

[CodyCleo]

I appreciate both of you taking the time to respond to this.  The first fight started when they were both called over together by my boyfriend sitting on the floor.  The older dog immediately went after the puppy which I believe was out of jealousy.  I, of course, being caught off guard and panicking.  I screamed and yanked my older dog by the collar off the puppy.  (which was not easy!).  I realize now was not the smartest choice. My kids and everyone involved were shaken up and scared.  A dog fight is not an easy thing to watch.  The older dog (Cody) had been with another dog before a Shepard Mix that I had to put down about 6 years ago.  They were together for about 7 years with maybe 2 fights randomly over a bone but nothing serious.  After Cody and the puppy (Cleo) fought I separated them and let them cool off.  I let them back together and they seemed ok but again another mistake, Cleo took a toy from him and the fight started again.  I have since went back to keeping a baby gate separating the house and alternating them on both sides. removed all toys where they will be together.  My kids 13 & 16 both keep them separated unless I am home. I was told NOT to reprimand Cody at first when he growled and to always keep things positive.  I now correct him when Cleo jumps up on the gate and Cody does a low growl.  You asked if he goes after the puppy unprovoked, after the inital fight and putting them back on the leashes, he does try and go nip at her now.  Sometimes, he will wag his tail and go down in a bow but as soon as she tries to play he then starts to growl. Cleo is very submissive and will put her ears down.  She will back up and give him his space.  I am just unsure how to proceed from here.  I don't think keeping them constantly restrained is good either.  Do you think when I am home I should just let free?  Again... very apprehensive about another fight.

[Margot49]

Good advice from Ginger but it can be difficult to evaluate a situation without actually seeing what us going on.
You have not introduced a puppy but a teenager,  :-)
What do you mean about the older dog showing aggression exactly?  Is the older dog actually going after the young one unprovoked?  
Look up some of Caesar's ideas on introducing new dogs.
Do take his advice and walk them with you in the middle. Make sure your older dog gets fed first, petted first, etc.  do not leave them together unattended.  If you see signs of dominance from the older dog, nip it in the bud, you have to be the pack leader.
If you have children, please do not leave them with the dogs unattended.
I would not leave any chew toys or bones down they may fight over.
Like I said, hard to advise without seeing what us going on and they do need to work it out.  Make sure your older dog isn't being bothered by the pup all the time.  
Unfortunately, this just may not be a good fit and you may have to find the young one a new home but hoping it will work out.
Please keep us posted.

[ginger899]

It's my opinion that these are not fights, as such, but your older dog laying down the law. She is saying "This is my pack and I am way higher in the pecking order than you, and you had better know your place."
That's what I think is going on.
Usually with pack-order squabbles, it is best to let the dogs sort it out.
Your older dog may well accept you (or your partner, or both) as Pack Leader(s) but as far as she's concerned the newcomer is bottom of the pecking-order.
What will probably happen, I think, is that the young dog will understand this, from chastisements and cues given by the older dog. Then the pup will quickly grow to learn it is lowest in the family, behave appropriately (n dog language anyway) and peace will be restored. Although there will always be a reminder here and there from the older dog.

Sometimes these pack "sortings-out" can appear scary to us, and aggressive, and we separate them or interfere, for fear of damage being done. But left to their own devices they usually organize the order of things. The one enforcing their status will growl, bare teeth, snap or even lunge at the other, and the submissive one will nearly always yelp.
What should happen is the submissive one should show signs of submitting to this discipline. (cowering down with ears down and wagging tail, rolling on belly, getting their body lower than the dominant one) So long as those things happen, the dominant one will usually back off, having enforced the rule.
If that doesn't happen, then it's trickier, because there is a battle of wills for dominant position. It's then that trouble CAN occur. Older dogs/wolves are sometimes challenged for top rank in a pack by a younger one, and there can be a real fight.

Of course, there can be exceptions, so do keep a careful eye on them. Try not to be scared, panic, pull them apart (unless things are going way too far) scream, or anything else. Keep a watchful eye on them, but try to let them sort it out first.