https://www.vetsurgeon.org/f/clinical-questions/9641/inactivated-felv-vs-subunit-felv Hi all, Question on something that perplexed me over the weekend. We deal with a few rescue centres that routine use Pentofel as their first vaccine choice. This includes a fully inactivated FeLV. We however use Virbac Leucogen which is a subuniten-USTelligent Community 10https://www.vetsurgeon.org/thread/47830?ContentTypeID=1Mon, 24 Oct 2011 13:11:04 GMT146601cc-3922-4be7-9974-7e1d4e45a66b:b7991132-5065-4bea-8bc9-ad5de9b73677Martin Atkinson<p>I believe one of the main reasons rescue centres use Fevaxyn is because it is a completely inactivated vaccine and thus reduces the risk of vaccine strain disease from&nbsp;spilled&nbsp;vaccines being transmitted to other cats. Being&nbsp;inactivated&nbsp;it is&nbsp;also&nbsp;heavily adjuvanted &nbsp;which&nbsp;is why there are more&nbsp;reports&nbsp;of post&nbsp;vaccination&nbsp;reaction than other brands. I use Pentofel but due its lack of&nbsp;availability&nbsp;may have to complete some course with a different brand. I wouldn&#39;t be&nbsp;concerned&nbsp;using a&nbsp;different&nbsp;brand/type of vaccine for a second shot and wouldn&#39;t be concerned a third vaccine was needed, more that I can&#39;t complete the chlamydophila course.</p><div style="clear:both;"></div>