Each 100 mg BOSULIF tablet contains 103.40 mg of bosutinib monohydrate, equivalent to 100 mg of bosutinib; each 500 mg BOSULIF tablet contains 516.98 mg of bosutinib monohydrate, equivalent to 500 mg of bosutinib.
Having said that, If your dog is itching and scratching all year long, then it's most likely due to either a food allergy or an allergy to something that is present all year such as dust mites or possibly even mange. In either case, you'll probably need more help to determine the cause which you can find here.
If your dog is continually itching one part of their body then they might have a tick. Look for a small lump on their skin that is akin to a wart and you might have found your culprit (dogs pick these up from long grass and heather).