Adjusting rent when a pet dies?

[Christopher Scott]

We've had issues with damage from dogs in the past and hadn't been allowing them recently. Our current tenant was a great fit but had a dog and offered to pay approximately 5% more rent each month in order to allow them to have the dog. Now the dog is in poor health and they are contemplating putting it down. The renter asked for an adjustment down of the rent given that a dog will no longer be living there. Thoughts? The increase rent was ostensibly for potential damage caused by the dog which may have still occurred however their argument is that the dog can't cause any further damage and therefore the damage will be limited.