The issue of a residential tenant deciding to get a pet in the middle of a current lease term doesn’t come up nearly as much as you would expect, but every so often it does. In most cases we do require a pet deposit to cover any damages that the pet may do to the property.
Legal technicalities aside, the landlord has a good practical argument for retaining the whole deposit [until the end of the lease]. The increased deposit was intended to provide coverage for any damage the dog might do. The landlord may not know about any such damage until you move out, even though the dog is long gone.
The above quote is from a post on Inman News in a Q&A column that I thought was worth sharing here (click the link to see the rest of the article).
Not only is the post a good primer on the ins-and-outs of security deposits, but also on the general nature of leases and how changes to an existing lease should be handled. This is important information to understand for both landlords and tenants. Basically, lease terms can’t just be changed at the whim of one party (duh!) — while that seems like it should be taken for granted, you would be surprised how often we have to explain that in the normal course of business.