Prolonged Case of Demodex

Question
My five month-old english bulldog was diagnosed with localized demodex about a month ago and it has since become generalized demodex. The vet started her off with a topical treatment and then moved on to Ivermectin. She's been taking the Ivermectin once daily for about two or three weeks and there has only been minor improvements. Her original spots are still there but the recent ones have started to clear up. The spot that has been particularly persistent is the original one where the vet did the skin scrape. The hair still hasn't grown back and there has been a bit of discoloration from the scrape. The vet said she needs to stay on the Ivermectin until she has three negative skin scrapes. She's had two so far and they've both been positive, and he said he wouldn't be surprised if the next one is as well. I know demodex can be tough to treat, but I'm just getting frustrated because she was scheduled to be spayed next week and now cannot have the surgery until the demodex has cleared up, which from the sounds of it won't be for at least the next month or two. My dog doesn't seem to be bothered by it but I feel terrible seeing her with these patches of missing hair. I got her from a very reputable breeder and have contacted them about this, and they said they had not heard of any of her littermates having similar problems. How long does a case of generalized demodex typically take to treat? Also, if she goes into heat before I'm able to spay her, will she react any differently to the procedure than she would if she'd been spayed earlier? Thanks so much for your help.

Answer
If you have a puppy this young with generalized demodex, you have a long road ahead of you. The prognosis is not good.

If you can get her cleared up long enough to get her spayed, that might help, but this is something that will crop up everytime she's put in a stressful situation her entire life.

This is caused by a defective immune system and it is genetic. Your breeder should be ashamed of themselves. I find it extremely hard to believe that none of the other puppies haven't shown up with it yet, but again, your puppy is very young. Usually you see this around 7-8 months old.

Your vet is on the right track but this is a very long, discouraging situation.