You are here:

Canine Behavior/Sudden aggressive behaviore


Hi, I have a four year old Toy fox terrier and we've owned him since he was a few weeks old. Ever since then though we've noticed that whenever he's asleep he'll suddenly lunge out and bite us with no provocation at all, we've looked it up and we think it may be a neurological problem, a common one where they're defending themselves from dangers.

Our dog is a sweet heart, and other then maybe the occasional problem with another dog, this is the only act of aggression we've seen. But for the past week or so he's been doing this nightly and sometimes while awake and my step father is on the verge of getting rid of this dog and we have no idea what to do for him other then to keep him off the couch and bed since those are the only places they seem to happen.

Please! I need help! I don't want to loose my dog!

This might be neurological and also a reaction to food ingredients (believe it or not).  The adage "let sleeping dogs lie" is true for a good reason.  However, your dog appears to have begun to generalize his reaction.  In the past week, he is rapidly advancing; whether or not he's truly "awake" I can't tell, but he has clearly learned (from Human response) that aggression WORKS (people back off: first big mistake.)

First:  You absolutely need a veterinary behaviorist.  This is a professional capable of evaluating your dog for any biologic cause.  I suspect that the couch and bed have become a part of his generalization.  He may be resource guarding but it may have begun as a neurological problem or even an occult illness (I have seen sudden guarding behaviors develop due to encephalitis).  Find a veterinary behaviorist from the following site or by calling the veterinary college in your geographical area:

If this turns out to be behavioral, it can be EASILY REMEDIED.  There is NO NEED for this dog to be re-homed.  I can help you to do that.

MEANWHILE:  create a safe, warm spot in the kitchen (soft and comfortable bed in a corner, under a table, etc.) where the dog will sleep.  Put a house tab on the dog: this is a very lightweight leash (cat leash) and use it to remove the dog from the furniture EVERY SINGLE TIME he gets up on the furniture.  Do this without anger, do not make eye contact, remain casual, pick up the leash, say "off" in a calm voice, and the moment the dog's paws hit the floor, praise and toss him a treat.  If this is behavioral, he will challenge you by repeatedly getting up on furniture.  Continue removing him, no matter how annoying it is.  IF he begins to show teeth or growl, stand your ground, no eye contact, wait for him to stop, say "off" and reward him for hitting the floor.  This should stop the dog from attempting to get up on the furniture but it may take considerable time.  NEVER set a dog up to fail; do not provoke an aggressive response.  Simply take charge and let him know you ARE in charge.

There is a behavior modification program that will put your dog in a lower position in social hierarchy.  It is simple, it is humane, and it works.  Before we use it, I would like to see what a Veterinary behaviorist has determined.  Use followup feature to advise.

Canine Behavior

All Answers

Answers by Expert:

Ask Experts


Jill Connor, Ph.D.


I have spent my entire professional life rehabilitating the behavior of the domestic dog and I can answer any question regarding any behavior problem in any breed dog. I have answered more than 5,000 QUESTIONS on this site in the past (almost) eight years. If you are a caring, committed owner and need advice, I'm here for you. I am personally acquainted with my colleagues (Turid Rugaas, Ian Dunbar, etc.) who were members of an elite group in EGroups that I founded: K9Shrinks. THERE ARE NO QUICK FIXES for serious behavioral issues; not only is it unprofessional to offer same, it is also unethical. IF I ASK YOU SUBSEQUENT QUESTIONS, I NEED YOU TO INTERACT WITH ME. More information equals more credible answers and a more successful outcome. If you want ANSWERS THAT WORK, participate in any way I request. I'm quite committed to working on this site for YOUR benefit and the benefit of YOUR DOG. Help me in any way you can.


30 years of solving serious behavior problems in domestic dogs; expert in dog to human aggression; Internet columnist for for 5 years; former radio talk show host, WHPC.FM, Garden City, NY "Bite Back" (1995 through 2000). List owner, international animal behavior experts, Seminar leader: "Operant Conditioning and Learning"; "Aggression in The Domestic Dog"; "Solving Problem Behaviors" -- conducted for various training facilities on Long Island from 1993 through 2000. Former clinical director of "Behavioral Abnormalities" in conjunction with Mark Beckerman, DVM, Hempstead, New York.

Member, APDT (UK); Psychologists in Ethical Treatment with Animals

Harcourt Brace Learning Direct: "The Business of Dog Training" "The Fail Safe Dog: Brain Training, not Pain Training"

Ph.D., UC Berkeley

Past/Present Clients
Board of Directors: Northeast Dog Rescue Connection; The Dog Project; Sav-A-Dog Foundation; etc. Pro Bono counselor: Little Shelter Humane Society My practice is presently limited to forensics. I diagnose cause of dog bite, based upon testimony before the Court, for attorneys and insurance companies litigating dog bites, including fatal injuries. I also do pro bono work for bona fide rescue organizations, humane societies, et al, regarding such analysis in an effort to obtain release for dogs being held for death in municipal shelters in the US.

©2016 All rights reserved.