"First, you should know that Ontario's Residential Tenancies Act does not permit landlords to include “no pet” clauses in rental agreements. The only exception is if the property is a condominium and the condominium corporation's declaration prohibits pets."

This is an important note for tenants who have been living comfortably in a rental situation for a time and have begun to discuss the idea of pets for their life in the future. However, as well intended as it is, this does not sufficiently aid those looking for rentals who already have pets. Though leasing parties can be reported to the Landlord Tenant Board for misconduct in their rental availability postings... that just doesn't get you any closer to finding a place to live.

The main things to consider are the stigmas against pet ownership and ensure that you anticipate the concerns of the Landlord in your application request. Attempts at full disclosure are usually the best way to ensure that a comfortable relationship proceeds with your future landlord (when possible).

Cats

• Litter
• Scratching of walls/furniture
• General odour
• Incontinence/territorial marking

Dogs

• Scratching of floors (largely dependent on size of the dog)
• Noise levels (especially if the rental has shared walls with other rentals
• Disruption of lawn maintenance
• General odour
• Incontinence/territorial marking

Give context to your pet. Providing the following information to your landlord can reassure them that the property will not suffer damage with you and your furry friends as tenants:

• Size/Breed
• General behaviours
• Level of training (in the cases of dogs, primarily)

Other information that can offset the discomfort of a landlord is a list of equipment you have for animal care to manage things like shedding, odour, scratching etc. Knowing how long you have had the pet also gives them insight into your knowledgeability and responsibility level as a pet owner. If the landlord has reason to believe that you understand what pets can do in the worst situations, and that you as a tenant plan to care for the property as if it were your own, they are much more likely to consider you as an exception. It can also sometimes help to provide a photo of the pet. 

Not everyone will concede to the fair and reasonable point of providing homes to those with pets, but some certainly will. My landlord is one of them. My cat, Clarence is especially happy in our most recent apartment. All it took was a little needs anticipation and a cute picture of Clarence sleeping on the couch--and good rental references, of course!