My dog has suddenly become aggressive

Hi. We have a border collie who is much loved by our family including my 13 and 8 year old daughters. She works sheep a few times a week, loves to play with a ball or a plastic bottle, and gets to sit in the kitchen for an hour or so in the evening but otherwise lives outside. (Unless it is very cold or wet.) She certainly has us ranked in order of importance, with my husband heading the pack, followed by the rest of us in age order. She is 12 months old now.

She used to love everyone who came to the door but recently decided she hates the postman. She now has added a number of other people to her hate list – including the gardener whom she has liked since she was a couple of weeks old. She barks with a very high pitched, frantic sounding bark and looks ferocious with her ears back and her stance low.

We had a horrible episode a few days ago when the plumber came to the house – he had been told to call before coming so I could put the dog away but he did not. He turned up in the dark and opened the gate, and the dog barked and stood in front of him so he could not approach the house. He shouted and kicked out at her, and when I got there (I am disabled and could not grab her collar) he made very threatening movements towards me and the dog. He kicked her and she nipped him.

Since that day she seems to be even more aggressive, and no amount of hushing her or holding her collar when someone she has decided she hates comes to the gate will calm her down. The irony is that when she meets the postman somewhere out of the yard, like at the shop, she is all over him with doggy kisses and wagging tail.

We are all at a loss as to how to improve the situation, and are afraid that she will seriously bite someone, or land up having to be chained up all the time. Please help!!

Our Response

Hi thanks for your question, it’s always a difficult and upsetting for you and your dog when their is a change in behavior.

Firstly it certainly won’t help the situation if your plumber is kicking out at your dog as this will only escalate the issue. The plumber was told not to enter until you were informed so he needs to be reminded that it is in his best interests to do this. Cover your back by putting a ‘Beware of the Dog’ sign up as this will inform any visitors/strangers. We know it’s upsetting to have to put a sign up, it doesn’t mean you are stuck with a dog with behavior problems it is only to cover your own back.

Ok firstly, any sudden behavior changes need to be looked at from a medical perspective as your dog maybe ill and need of veterinary advice.

I am also concerned as to whether something has suddenly made your dog aggressive to strangers – has someone been mean to your pooch to make her wary of strangers?

Your dog is actually showing guarding instincts and is at the age when these instincts start to develop – she is sexually mature and maybe battling for position as the pack leader or she may also be protecting you from what she sees as intruders.

Another important thing to remember is that is your dog spending enough time with people – socialization is so important and if your dog is spending large amounts of time on her own she may need to be around people more often. As you mentioned previously that your husband is quite clearly the pack leader, start getting your husband to spend more time with your dog. Invite people around and place a leash on your dog, when she barks and growls get your husband to show a negative response – a sharp ‘no’ will do. The most important thing is to use positive reinforcement and reward your dog when she is good and doesn’t bark and growl. You will need to practice this as it isn’t a quick fix. Continue bringing new people into your environment to remind your pooch that it isn’t just hers.

This isn’t going to be a easy problem to fix especially if your dog is outside allot of the time. Consistently reinforce positive behavior and spend time with your dog so you are able to anticipate positive and negative behavior as rewarding or correcting any issues ten minutes after the incident won’t mean anything to your dog.

Another thought is – if your dog is in heat – all sorts of hormones will be kicking around and you can really expect any behavior changes.

We hope this helps as it’s a tricky case and we would really need to be seeing and watching the behavior. Try some of these techniques and if you have a behavior trainer nearby who can work one on one with your dog, this maybe something worth considering.