aggressive behavior

Question
Hi
We adopted a cairn terrier, Bo (maybe mixed) from animal control about 16 months ago.  He is probably about 2 yrs old according to the vet.  I am definitely his property!!  He doesn't like anyone, including my husband, to get too close - good thing we're done having children!  Anyway, he becomes extremely aggressive toward certain people that come over.  One in particular is our neighbor's son, Clint, who is almost 17 yrs old.  Clint has never harmed Bo or even yelled at Bo but we have to watch Bo very closely when Clint comes over as he will bark, growl and try to bite Clint.  Clint (and his entire family) spends alot of time here so this is very annoying.  Bo does this to Clint regardless of whether Clint is near me or not.  Clint is just one example - Bo does this to alot of people but most of the time this behavior will stop after the person has been here awhile.  Clint has tried ignoring Bo, firmly telling Bo "No" and trying to pet Bo and talk softly to him.  Nothing so far has worked.  Do you have advice for us?  Thanks.

Answer
Dana -

Bo has now entered his teenaged period and is in the point in time in which his personality will be at it's most challenging assuming that the problems are addressed.  If they are not, this is the most often cause of cairns being surrendered to rescue or shelters - this exact kind of aggressiveness.

He is doing what is called resource guarding - and you are his resource. With time, his desire to control the environment is expanding from just your immediate vicinity to the household, and eventually you will see it outside the home as well.

There are a number of things I want you to consider implementing right away.

1.  You should not be in charge of feeding him, and you should never be the one to give him any treats.  It should start with you husband since he's there all the time, but once he accepts this, I would recommend that Clint start coming over to feed at least one meal per day.  They should put the dish not in it's usual spot, but at their feet and then stand up straight and not acknowledge Bo at all - no words, no looking at him, no reaching for him.  Let the little sucker have a fit, but if he wants his meal, he has to come near them.  If he does not do it in 2-3 minutes, pick the dish up and make him wait til the next meal (he won't starve assuming you feed twice a day).

Gradually I would like to see them work from having him eat at their feet to them being able to hold the dish while he eats, and ultimately be able to hold their hands in the dish while he eats.

2.  You should immediately implement Nothing In Life Is Free - see this link for a good description.  Bo's ego is getting too big for his own good and this is an excellent way to nip it in the bud without being mean or letting it get to the point where you are mad or it is dangerous:

http://cairnrescue.com/docs/NILIF.pdf

3.  You simply cannot tolerate this kind of behavior - I recommend crating him for 10 minutes every time he even thinks about acting like this. Don't wait for him to actually act out, then again, wait for him to start getting worked up to be nasty.  Then, without saying anything at all, grab him and put him in the crate.  Don't be mean, but be unceremonious. I recommend the use of a harness for this since it makes snatching so much easier.

4.  Finally, I strongly recommend obedience classes.  If you do not get him out and about on a regular basis, he will not be well socialized and you may well continue to have bad behaviors.

Please keep in mind that this kind of behavior not only threatens people's safety, but literally Bo's life.  If he should land a bite or 2, he will be in serious danger of being put down.

I hope this gives you some ideas about how to start.

-Beth