How many antibiotics are used in animals?

Veterinarians estimate that 300 drugs have been approved for use in companion animals like dogs, cats and horses.
Many of the compounds contain active ingredients that are identical to those in human drugs; some are used for the same purpose, but have different brand names.
Commonly prescribed are the following:
Amikacin
Amoxicillin
Amoxicillin/Clavulanate (Clavamox)
Azithromycin
Bacitracin/neomycin/polymyxin (triple antibiotic for topical or ophthalmic use)
Cephalexin
Chloramphenicol
Clindamycin
Doxycycline
Enrofloxacin (Baytril)
Gentamicin
Marbofloxacin
Metronidazole (Flagyl)
Nitrofurantoin
Tetracycline
Trimethoprim-sulfamethoxazole
Tylosin