Or you could try proposing a free-floating subdivision --Pets for use under personal names. That’s what the SACO Program is for! Can’t guarantee that it would be accepted, but one could try. It would need to be proposed under the pattern heading for names of persons.
University of Washington Libraries
Example: Portrait of a dog / by Mazo De La Roche, which is about her pet dog.
Just to make sure I’m not overlooking something, there’s no way to put “Pets” or “Animals” under a person’s name for a book about their pet(s), right? I haven’t seen anything in the LSCH or in the Subject Headings Manual in the list of free-floating subdivisions under “Names of Persons”. If you wanted to bring out the fact that the dog belonged to her, would you simply put Mazo De La Roche as a subject?
Cataloger, Monographs and Electronic Resources
Associate Professor of Bibliography
Description & Access Department
University of Oklahoma
Co-ordinator, Oklahoma (Tornado) NACO Funnel
Co-owner, PERSNAME-L, the list about personal names in bibliographic and authority records