If an animal is suffering, in immediate danger or in need of humane euthanasia, you can take it to the Ottawa Humane Society, Lost and Found Door (municipal animal shelter). Call first at 613-725-3166, ext 223 to let them know you will be arriving, and see their website for directions and operating hours. Alternatively, you can call Ottawa Bylaw for rescue help at 311.
For cases of animal cruelty or neglect, call 1-833-9ANIMAL.