If you somehow learn where they reside, please alert the local child protective services.
It is correct that I do suspect abuse. I know that her father has been emotionally abusive to both her and her 10 year old brother for years. Although I have no contact with my daughter, son-in-law or grandchildren, I know the father has been in individual counseling, father and mother in marital counseling and 10 year old in psycotherapy. Problem is I can't contact her to tell her your advice, don't know where she now resides so can't even make a referral to the local child protective services agency. I'm just very worried that no one in that household is willing to look at this behavior seriously.
She should be evaluated by a pediatric mental health clinician. Cruelty to animals is often, if not most of the time, a symptom of serious emotional disturbance. It can be a sign of having been abused, though not necessarily so. I'm inferring from your note that you suspect that abuse may have occurred. Is that correct?