Thank you all!!!
 
I have ordered the Frontline Plus to keep on hand.   I HOPE that the Sentinel along with non-proven preventions I am using (feeding 100% raw and using Minksheen) will be enough, but I realize in the city it might not be.  So if need be, I will use the Frontline Plus.  

  I've read up and ticks are not a huge concern. 
Much appreciate all the feedback!!!
Viv