In Shelterluv, treatments can be added to an animal's record with no end date or "until further notice" such as a probiotic to be given with meals each day:

To discontinue a treatment in progress, you can navigate directly to the animal's profile, then from the Medical > Treatments tab, click the three dots on the top right hand corner of the treatment card to edit the in progress treatment:

With the Edit Treatment window now open, update the "Until" field by choosing "Duration" then entering the date the last dose should be given to end this ongoing treatment: