terrier aggression

Question
Hello - I have a 2 year old, male, neutered Sporting Lucas Terrier.  He is my first terrier, having had gun dogs in the past without any major problem.  I have had him from 8 weeks of age and he is a wonderful dog except for two problems.  Firstly he becomes aggressive when he meets other, normally small, dogs whilst on the lead.  If off the lead, he is very excited and happy to meet other dogs.  Secondly, if he is in the car and sees another dog outside the car, he again becomes very aggressive.  He is never aggressive towards the family or people.  It is only other dogs that are either on a lead (or he is on his lead) or when he is travelling in the car.

He is well socialised and spends a lot of time with my parents' Springer Spaniel.  He also gets on well with our cat.

Any advice on how to stop this behaviour would be appreciated.  Thank you.

Answer
Rachel -

I have to admit I had to do some homework before I could even start to answer you !  I had never heard of a Lucas terrier and had to look them up since we don't have them here in the US. They sound adorable and wonderful.

In both instances of this behavior, I suspect they are a form of resource guarding - with the resource being his family members. This is not an uncommon problem with many terrier breeds.  The level of prey instinct and assertiveness gets redirected into situations such as this.

The way I usually untrain this behavior is to make sure I have a command absolutely perfect with the dog that is incompatible with acting out in that way.  In my case, I like to use "sit" and "look at me."  Then, as I can foresee than an incident is going to happen, I start having the dog do the command and liberally provide tiny bits of **very** high value treats.  I keep them doing the good things as a replacement for the behavior I don't like.

As a dog approaches, I take the dog off to the side as far as 5-6 feet, have them sit, look at me and start treating.  I try to keep them on these tasks until the other dog has gone past.  I would not expect them to be able to do it for the whole time right away, but given repetition, you will likely be able to build up the time. Once you have the time built up, you move a little closer to the line of traffic. Once you can stay in your original line of travel, you are seeking a point where he turns and looks at you when he sees another dog on a leash.  

I hope this gives you some ideas.  You may wish to initially set it up with a friend and their dog so you can practice when it's convenient.

Let me know how you make out.

-Beth