Elders can DFs anyone without any reason or cause. If they decide that you do not belong to WT, they can DFs you on any grounds whatsoever. I knew people who were DFs for citing Bible as defense and they were booted right there. I knew a person who was DFs for upheld belief in older publication and was not willing to accept the new light as it was not making much sense. He was out.
If you live in Europe, almost every country in EU has laws against animal abuse and what your father did, can be considered felony. At least in the Czech Republic animal abuse of dogs and cat is a felony where first offense is punishable up to two years and second offense up to five years in prison.