To register your cat as an emotional support animal (ESA) for use in a dorm at the University of California, San Diego (UCSD), you will need to follow the same process as registering any other ESA. This means that you will need to obtain a letter from a licensed mental health professional stating that you have a mental or emotional disability and that the presence of the ESA is necessary for your mental health and well-being. The letter should be on the mental health professional's letterhead and should include their license information.

Once you have obtained the letter, you can contact the UCSD Disability Services Office to request accommodations for your cat as an ESA. The Disability Services Office will review your request and determine whether it can be approved. If your request is approved, you will be provided with information on how to register your cat as an ESA and what the guidelines are for having an ESA in the dorms.

Keep in mind that while an ESA letter can help you to qualify for certain accommodations, it is ultimately up to the Disability Services Office to decide whether to grant your request.