Hello, thanks for your question today! I am Dr. Drew, and I am a licensed veterinarian. I'll be happy to help you in any way I can.
Itching is not a typical feature of demodectic mange, so it is unlikely that this is the cause of the problem.
if no mites are found, demodectic mange is even less likely, as true cases of demodectic mange feature many mites on skin scrapings.
sarcoptic mange is highly itchy,
and can affect other dogs and people,
and is not typically very responsive to prednisone.
As to the ivermectin issue --
I will do some calculations and return in a moment.
Thank you, XXXXX XXXXX wait for your answer.
0.5mL, for a 35 pound dog, works out to around 30-35 micrograms per kilogram of body weight,
which is still a rather low dose, all things considered,
and typically would not be likely to cause problems in most dogs, even if carrying the MDR gene which makes a dog more susceptible to the side effects of ivermectin.
50 micrograms per kilogram has been reported to be tolerated in dogs with this defective gene.
if you prefer, you can start at the half dose,
but I do not expect problems at the full 0.5mL dose.
Thank you for your answer. This does make me more comfortable with giving her the medicine knowing that it is a low enough dose that she should not be adversely affected, even if she has the defective gene. I think I will still start at the half-dose if it will not affect the efficacy of the treatment. I'm just a bit of a worry-wart I guess.
glad to help -- best wishes to both of you :)