Some antibiotics are approved for use in animals, others in people, and still others in both animals and people (also called shared class antibiotics), but the majority of antibiotics used in animals are non-critical to human medicine.
The Food and Drug Administration not only has an intensive approval process for drugs for animals that’s similar to the approval human drugs undergo, but the FDA performs additional studies on drugs for food-producing animals not required for human drugs to be sure meat, milk and eggs are safe for us to consume, and that the drugs are safe for the environment. This process is intended to ensure public health.
Comparing animal and human antibiotic use is complicated. That’s why the proper context is so important.