https://www.vetnurse.co.uk/f/clinical-discussions/11179/change-in-my-dogs-behaviour I have an 8 year old Border Collie (male, neutered), who until recently has been an angel with other dogs both on and off the lead. All of a sudden though he has started going for other dogs when both he and the other dog are on leads. This usually happensen-USTelligent Community 10https://www.vetnurse.co.uk/thread/100773?ContentTypeID=1Wed, 03 Nov 2010 19:32:21 GMT1a0763ec-3885-442c-853e-6cef656dfec5:7f7ef5fb-dcd9-4cb4-ba70-084a5ff66413Shelly vn<p>I haven&#39;t had him checked over and I definatly will. But i&#39;m not sure its his eye sight as he spends hours chasing tiny reflections from shiny things!! What I can&#39;t get my head around is how the change in him was so sudden. He was fine on the Sunday and walked past other dogs fine and Monday he was a different dog. He has had other behavioural problems in the past (what collie hasn&#39;t!) but this is the first thing for ages.</p><div style="clear:both;"></div>https://www.vetnurse.co.uk/thread/100772?ContentTypeID=1Wed, 03 Nov 2010 19:18:40 GMT1a0763ec-3885-442c-853e-6cef656dfec5:1f59dff2-e688-4771-a82c-e426aad8bcbfDoolally<p>Have you had him checked over by your vet? Could be his hearingh/eyesight going, or some other medical problem. &nbsp;It may be he&#39;s been coping fine with say slightly less than perfect eyesight, but the poodle incident has knocked his confidence?</p> <p>I&#39;d get him checked over thoroughly first, and then work on building his confidence on the lead away from other dogs and then gradually reducing the difference. &nbsp;Get him working on the lead, look at me, sits etc so his mind is on you rather than the other dogs.</p> <p>I know how you feel, my dog was attacked quite badly almost a year ago, and he still has funny days where he refuses to walk, where I just can&#39;t work out what it is has upset him, I so wish they could talk!</p> <p>&nbsp;</p> <p>&nbsp;</p><div style="clear:both;"></div>