Who does custody evaluations? Well, it depends on who is being evaluated.
In some states, veterinary animal behavior specialists serve as the experts who advise which separating “pet parent” should have “custody” of the family pet.
One such pet custody evaluator explains her methodology in a process which takes about an hour and a half. Part of the evaluation is based on responses of the pet parents to questions at an interview. The remainder of the evaluation is based on observation of the pet’s interactions with the pet parents.
“Calling contests” are not considered reliable indicators.
Ultimately, the pet custody evaluator seeks to determine which pet parent the pet has a stronger bond to and preference for, and who the evaluator thinks would better care for the pet.
Equal timesharing is not usually recommended because many pets find such an arrangement emotionally challenging.
Read more in this Boston Globe article: Lawyer for the dog.