The smell never bothered me. Made the dog yelp a bit though. Our Vet did it, then I found out later that she was newly pregnant but she never flinched
Fleas did cross my mind too. I've shut her on her own with a bowl of food and another of water so that I can see if she vomits in the night and whether she eats much. Then I'll decide ……..
I did look on U-tube ……… but she isn't my cat so I don't know how she would react if I started jabbing about round there. She's not a lap cat so difficult to hold still for long.