I have an 11 month old male Border Terrier who has always been boisterous but never aggressive towards other dogs. On walks, he is off lead 90% of the time and friendly towards all other dogs - tail wagging, only wanting to play or happy to walk on.
Two weeks ago, he was approached in the park whilst off lead by a German Shepherd puppy who was younger than him but larger than him. Instead of his normal behaviour, he dropped a tennis ball he had in his mouth and lunged at the dog. Being young, the German Shepherd was very submissive and did not try to fight back. It took 20 seconds or so of the GS running away from my dog, with my dog chasing and snarling to separate them. I was completely in shock, having never seen any kind of even low-level aggression from him before. Afterwards, we thought it may have been him being possessive about the tennis ball, or over my sister's dog who was with us on the walk, and this may have triggered the behaviour, with my dog possibly thinking he was being defensive.
Since then we have not allowed him tennis balls near other dogs and we have had no problems. His behaviour has been friendly to every dog, big or small, young or old, since. Today I took him out and he met a very young puppy, smaller than him and maybe 3 months old. He is usually very friendly with puppies. Immediately upon making contact with the puppy he again lunged at her and, when the owner picked her up and I went to grab his collar, he began jumping up towards her to get to her. I don't see this as defensive and certainly was an attack since he continually wanted to go back to her despite her being no threat.
I took him home immediately and am lost as for what to do to stop this infrequent but unpredictable behaviour. He has not been neutered yet due to advice we received on younger neutering encouraging fear based aggression, which I wanted to avoid. Little did I know that 2 months later he would display aggression twice within a month regardless. I know that his testosterone is peaking around 10-11 months and that this will tail off, but I am worried that this kind of behaviour could be permanent. For now he will not be allowed off lead around other dogs. Can anybody advise whether this is something they know of, and whether this is reversible or permanent behaviour?
Two weeks ago, he was approached in the park whilst off lead by a German Shepherd puppy who was younger than him but larger than him. Instead of his normal behaviour, he dropped a tennis ball he had in his mouth and lunged at the dog. Being young, the German Shepherd was very submissive and did not try to fight back. It took 20 seconds or so of the GS running away from my dog, with my dog chasing and snarling to separate them. I was completely in shock, having never seen any kind of even low-level aggression from him before. Afterwards, we thought it may have been him being possessive about the tennis ball, or over my sister's dog who was with us on the walk, and this may have triggered the behaviour, with my dog possibly thinking he was being defensive.
Since then we have not allowed him tennis balls near other dogs and we have had no problems. His behaviour has been friendly to every dog, big or small, young or old, since. Today I took him out and he met a very young puppy, smaller than him and maybe 3 months old. He is usually very friendly with puppies. Immediately upon making contact with the puppy he again lunged at her and, when the owner picked her up and I went to grab his collar, he began jumping up towards her to get to her. I don't see this as defensive and certainly was an attack since he continually wanted to go back to her despite her being no threat.
I took him home immediately and am lost as for what to do to stop this infrequent but unpredictable behaviour. He has not been neutered yet due to advice we received on younger neutering encouraging fear based aggression, which I wanted to avoid. Little did I know that 2 months later he would display aggression twice within a month regardless. I know that his testosterone is peaking around 10-11 months and that this will tail off, but I am worried that this kind of behaviour could be permanent. For now he will not be allowed off lead around other dogs. Can anybody advise whether this is something they know of, and whether this is reversible or permanent behaviour?
