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Understanding Jack Russell Aggression

JRT aggression is often a symptom of underlying problems. Their behavior might be a result of fear (they’re going with the “attack is the best defense” tactic), lack of socialization, possessive behavior or even boredom and pent up energy due to lack of physical activity.

Before handling the situation you have to correctly determine which one of these factors, or their combination, is the root of the issue. Only then can you start correcting the unwanted behavior, otherwise you could do more harm than good. And as always – use only positive training methods.

It’s important to differentiate their aggression towards humans and other dogs from their strong prey drive that makes them look at cats and small rodents as targets rather than housemates.

They are also quite intolerant to other same sex members of their own breed and fights among Jack Russells in larger groups are common. It’s best to keep a maximum of two Jack Russel Terriers of different genders in one household. Any more than a pair cannot be left alone without supervision.


If you haven’t worked enough on socializing your JRT they may be fearful of people and dogs that they aren’t familiar with. Work with them from an early age – introduce them to lots of different people and other dogs in a positive manner. At first do it in a safe environment that they already know and that you can control, such as your home and with time expand your play dates to the great outdoors.

They are also very good at reading your own emotions so they’ll pick up on your own “vibes” and act accordingly. If you get startled or agitated they’ll also express their fear and dissatisfaction in their own dog way – by growling, barring their teeth and preparing for defense not only of themselves but their beloved human. If such a thing happens regain your calm, take control of the situation and show them that their fear is unwarranted.


JRTs are a very active and intelligent breed. As I’ve mentioned many times before, you can’t expect a Jack Russell to lazily mop around all day without a care in the world. They are eager for some action and if there isn’t any readily available they’ll provide some themselves. Be it destruction of their surroundings at the worst or being a general nuisance at best.

Make time for them – they are a true companion not just another fixture in your home. Vigorous outdoor physical exercise (at least 1 hour daily) and keeping their mind occupied with various training exercises indoors and outdoors throughout the day will keep them happy and entertained. It’ll also spend some of their seemingly endless energy and leave them content.

Possessive behavior

Jack Russells are real characters and have a big personality. And by that I also mean that they often seem to believe that they’re much much bigger than 10 inches high in the shoulders. Their incredible courage in the face of adversity is well documented, but they can also be quite confrontational and stubborn towards other dogs, people, bicycles, cars, bears, you name it, and their small physical stature doesn’t seem to faze them at all.

Their high opinion of themselves can sometimes embolden them to try and boss you around: “Go there! Give me that toy NOW!” The little rascals will try out your limits, especially if you aren’t enforcing the rules and correcting their negative behavior with positive methods.

JRTs get really attached to their guardians and can be hostile to other people that they perceive as intruding in their space – even other members of the household that they for some reason deem less worthy of their two-legged companions time and affection.

Everybody must work together to make them comfortable and relaxed – that includes a lot of yummy treats, praise and shows of affection from everybody involved so they associate people that surround them with nice, happy feelings of content and security, and not to perceive them as adversaries for their favorites attention.

Muzzel is a must

If your dog is showing signs of aggression you, for your own and safety of others – your own dog included, must accustom them to wearing a muzzel, especially outdoors where you can’t completely control the environment. Contrary to popular belief, wearing a muzzel isn’t a punishment for your pup.

They must get accustomed to it just as with all other parts of your equipment – collar, harness, etc. and you must help them embrace it as something fun and normal. The goal is stopping them from biting, and not restricting their expressions or normal bodily functions.

While wearing the muzzel they have to be able to open their mouth, sniff, take treats, drink water, pant, bark at all times – that is why you must use a basket type muzzel like the sturdy but comfortable Baskerville Ultra Basket Dog Muzzle. You must make sure that it’s a comfortable fit, that they aren’t too restricted but also that they can’t shake or scrape it off.

Use high value treats while getting them accustomed to the feeling and soon they won’t even notice it’s there, especially if they have enough room to move their mouth and do all the

If you tried to correct the aggressive behavior yourselves and you weren’t successful don’t despair – it’s hard and complex work and you just might need a help of an expert. Do some digging and find a trainer that specializes, or at least has plenty of experience working, with aggressive dogs and, this is very very important, uses only positive training techniques.

Do you have some experience with JRT aggressive behavior? We would like to hear your opinions and advice in the comments below.

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