hair loss

Question
I have 2 goldens and a bloodhound. I have been able to maintain homeostasis with all of them; but within the last week I have noticed my youngest golden losing hair on her lower back ( thinning) I don't see any fleas or flea feces. The only thing that was different within the last couple of weeks was that I applied a new kind of topical flea medication on all three. The other have not reacted to this. Just wondering if this could be the culprit. The medication was Bio-Spot.

Answer
Too bad I am too ethical to use All Experts to refer you to another Q&A site that just had a big discussion of this.  Maybe I will at least copy one of the better posts.  

''I don't use it due to ingredient, I prefer frontline, the plus is mearly a tic deterrent the added cost doesn't seem that much of an economic advantage in my dogs living situation. Jake goes everywhere with me, so he basically would be the one at risk, I figure he is 21 now, he hasn't died from any of my medical experiments by now IM not worried about a tic. Frontline and Advantage have the same active ingrediente as raid roach motels. lil trivia for ya, perfectly safe if orally consumed other than the plastic. Bio spot can cause a reaction in some dogs, that's why I personally don't suggest it, but I know others that have no medical issues with it at all. That small percentage of dogs that do or could keeps me from suggesting it. I hate when people come back to me and said, YOU KNOW THAT so and so medication You said to use almost killed my dog, and you call yourself a VET! lmao never fails, So in avoidance to even the smallest chance of that convo, I learned later that the almost died dog required a dose of Benadryl for a miracle recover