Antibiotics target specific types of bacteria and do not work against viruses. Common veterinary antibiotics include amoxicillin, cephalexin, and enrofloxacin. Completing the full course is critical even if symptoms improve early, because stopping prematurely encourages antibiotic-resistant bacteria. Never give human antibiotics to pets without veterinary guidance, as dosages and safe drugs differ between species. Some antibiotics cause side effects like diarrhea or appetite loss, so report any changes to your vet promptly.