Dear [Name of tenant]
Re: [Property Address]
I am writing to inform you that I’m aware you are keeping a [type of pet] at the above property which is unacceptable, and in breach of our tenancy agreement.
Please therefore make the necessary arrangements for any pets be removed from the property immediately to ensure that you are no longer in breach of the terms of your tenancy agreement.
I wish to remind you that no request was made by you to keep a pet at the property and in this instance I can confirm that I would not have granted such permission.
Please do not hesitate to contact me should you wish to discuss this matter further.
Thank you and I appreciate your cooperation in this matter.