I have had that problem now three times! The first time the owner missed a dose and I was able to wash her with blue dawn and the fleas died.

The second was on Sentinel and we get fleas in the yard due to squirrels (two pecan trees) dang squirrels won't wear a flea collar, lol. Anyway the owner ordered a chewable flea killer and we are using that, she is with me a month. She was able to come into town an arrange otherwise I was going to do capstar and get a prescription with my vet.

The 3rd time was just this weekend, a new client had a funeral (obviously not a planned event) so it was a no meet and greet drop. It was a small dog that really needed a groom and ears were completely gross. This dog smelled terrible and had fleas. I went ahead and bathed her after getting out the mats I could without shaving her down. (Luckily I groomed my own mini schnauzer for 14 years or how would normal sitters even know what to do?) That is when I discovered the fleas and her poor ears. I went ahead and cleaned her up but I have decided at the advice of my vet to keep some Capstar equivalent at my house. If I were to get it each time from the vet it is $10 a pill. I can get cheaper in bulk but am wondering if I could add on $10 as an extra. I will disclose in advance to owners that if I find a flea I will treat and it will be a fee. The 3rd owner acted as if I was a mean guy for saying her dog needs a full groom. I didn't offer because I am not a trained groomer heck I didn't charge for the bath or the mat removal I did too.

Anyway you can get the active ingredient on Amazon shipped for 50pills for about $15 and I am going to stock up as flea season is coming up.