California Canine Co. owner Dierdra McElroy demonstrated the use of her cancer detecting dogs recently for a Rotary presentation at Spring Creek Country Club – reporting 375 positive peer review studies over the past five years. McElroy, who provides the ‘Didi’s Dogs’ column on a regular basis for The Times, is from Lathrop. She brought a black lab, Karma, into the meeting room at Spring Creek where the dog showed its proficiency at locating the one hole that would normally contain urine from a suspected cancer patient and hit on the correct hole that in tests confirms the presence of a malignant tumor below stage one of its growth.