1_The biggest risk is the development of antimicrobial resistance. So when animals receive too many antibiotics, bacteria can become stronger and no longer respond to the drugs and that's a big issue.
2. When antibiotics are overused, they can enter the environment through animal waste, which spreads into soil and water. Which can harm beneficial microorganisms that support plant ,Spread of resistant bacteria in wildlife and natural habitats
So we can say it reduces biodiversity and weakens the balance of ecosystems, making them less healthy and less productive.