Hi and a belated welcome to the forum. I'll try not to repeat what others have already shared so I will keep my comments focused on things that have not been covered in detail. Boxers are definitely a breed that seems to be genetically cursed and are predisposed to calcinosis cutis (cc) which is a rare and very trying symptom of cushing's. A skin cytology with tape may pick up a secondary bacterial infection which is common with cc, but I'm not sure cc can be identified without sending a piece of one of the lumps out for examination. Cushingoid dogs with cc need to be on twice daily dosing of Vetoryl or compounded trilostane. I see that you will have liquid trilostane so this good because you will be able to split the dose prescribed in half and give with a meal in the am and pm. As Lori has already mentioned, it is known that many large dogs require much smaller doses of trilostane to achieve effective control of cortisol and has provided a link to the 2014 study done by UC Davis. The results of that study have also been validated by many veterinary teaching institutions across the globe who have set their own starting dose protocol ranging from .1 to .5 mg per pound of body weight. With your dog weighing 75 lbs, most specialists would likely start her on no greater than 15 mg twice a day. We have seen so many big dogs overdosed so we go to great lengths to share as much information as we can with members. In addition to the link Lori provided, I am providing additional links to handouts for lectures/presentations given by prominent endocrine experts that touches on this subject. If your vet has taken any continuing education on the canine endocrine system, he/she will most likely have heard of Dr. Edward C. Feldman, Professor Emeritus UC Davis and Dr. Claudia Reusch, Professor and Director of Clinic for Small Animal Medicine at University of Zurich. Please either share these links or print out the documents for your vet so he/she is aware of this most important development.
https://drive.google.com/file/d/0B5R...ZrNmlXZHM/view
https://www.vin.com/apputil/content/...UE5AlZP-w5HfCg
If you have a facebook account, I recommend that you consider joining the Dogs with Calcinos Cutis support group. Please use link below. Members there share their experience with what has worked and what hasn't worked for their dogs. Unfortunately there is no single oral or topical medication that works for all dogs. There are lots of pictures posted by members of that group as well. You will definitely see a lot of short snouted breeds like Boxers, French Bulldogs, Boston Terriers and English Bulldogs. The administrator of that group created it as a moral support network, not a place to learn about cushing's so you definitely want to stay here as you'll find no better educators or resource library elsewhere.
https://www.facebook.com/groups/988564191285009/