Hello Hilary, I'm Dr. Deb.
I recently came online and see that your question about Penny hasn't been answered. I'm so sorry that you've had to wait for a response,but if you still need assistance, I'd like to help if I can.
I can understand how frustrating this must be for you but clearly you are not the only owner with this particular problem when it comes to Vetoryl (or other medications for smaller dogs, for that matter). When treating my smaller breed Cushing's Disease patients, I have Vetoryl compounded by a special pharmacy into the dosage I want since to the best of my knowledge 10 mg is the smallest manufactured size. It can also be compounded into a treat or a flavored liquid for those difficult to medicate patients.I'm fairly certain that this service is provided for vets and their owners in the UK (LINK).There are other treatment options for this condition such as Mitotane (LINK) which was the only drug available some years ago. Since Vetoryl has become more widely available, many vets consider it the treatment of choice for Cushing's Disease although this may also come down to personal preference.I hope this helps although, again, my apologies for the delayed reply. Deb