[theBCnut]

Definitely do not give 1/2 a pill and then the next month the other half. Trifexis is not stable when exposed to air and 1/2 pill is not enough. Consider giving 3/4 of a pill and throw out the rest. Hound Dog Mom had a great suggestion, unless you live in an area where you have flea etc. issues all year round, you might want to avoid the excess chemicals when you don’t need them.