https://www.vetsurgeon.org/f/clinical-questions/19354/vectra-tick-flea-rx We have changed from the fipronyl based flea products and are trying out the Vectra - so far so good but we have seen 2 dogs different breeds, different households with vectra applied 24 hours &amp; 72 hours showing cns signs of walking sideways on withen-USTelligent Community 10https://www.vetsurgeon.org/thread/116241?ContentTypeID=1Wed, 18 Jun 2014 23:24:54 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:6868b071-4b9b-4d15-874c-ea75907305b3Stephen Courtney<p>You should report the suspected adverse reaction to the VMD regardless - it can take time for things to show up, and it might be something new or unexpected e.g. an atypical batch - and watch/ wait and see what happened. We haven&#39;t used Vectra 3D but it looks like a pretty good product, so interested to hear how this goes.</p><div style="clear:both;"></div>https://www.vetsurgeon.org/thread/116230?ContentTypeID=1Wed, 18 Jun 2014 18:33:26 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:a209d757-0f52-4aeb-848a-4779ca15ca4cBob Russell<p>We have had one case where the dog was distinctly unhappy after application. Skin irritation/burning sensation has been described. The active ingredients have a well established safety profile over many years so not really expecting that to be the issue. Unless someone knows different of course!</p><div style="clear:both;"></div>