I want to make sure I understand your question. You are asking about the potential side effects on you and your family from handling the Leukeran and giving it to Molly?
OK Julie, thanks for the information.
Let's start with the side effects for Molly. They will be similar to her other chemo drugs: gastrointestinal upset (vomiting, diarrhea, decreased appetite) and bone marrow suppression (increased susceptibility to infection, anemia, trouble clotting blood). These usually occur within 1-2 weeks of starting therapy and usually resolve within 1-2 weeks of onset. Severe bone marrow suppression can rarely take months to years to resolve.
The drug's active metabolites are excreted in feces and urine, so exposure to either should be avoided. Wear gloves to pick up feces. As she will be on a three week course, urine and feces should be considered contaminated through the entire course and for a few days after finishing therapy, similar to the other drugs. Exposure to urine on the lawn is likely minimal, but you might consider only having her urinate and defecate in an area of the lawn where no one goes, and watering it regularly to dilute out any residue.
Licking shouldn't be much of an issue as long as she swallows the pills and doesn't chew them up, but to be on the safe side i would try to minimize it.
Since you are on immunosuppressive drugs already, the biggest risk is for you, since the leukeran can cause additive marrow suppression in you. Wearing gloves to handle the pills and pick up feces (or having someone else do it for you), washing your hands regularly after coming in contact with Molly, and avoiding the area of the yard where she urinates are all prudent actions for you.
Ultimately, it comes down to benefit vs. risk. Side effects in Molly won't be all that common, and with appropriate precautions, your exposure should be minimal to nil. That said, injectable chemo tends to be more fast-acting and have more options, so you might consider a second opinion on protocol from another local vet or veterinary oncologist before committing to Leukeran.
Happy to help. Good luck to you and Molly and please let me know if you need anything else.