Oral antibiotics for cats

Updated April 17, 2017

As defined by Pet, "an antibiotic is a chemical substance that either kills or inhibits the growth of microorganisms." We take them when we have a bacterial infection and so can our cats. Antibiotics are used to treat a wide range of feline bacterial infections, including eye, ear and skin infections, urinary tract infections, underlying bacterial infections associated with upper respiratory disease and the tick-transmitted disease, ehrlichiosis. Cat antibiotics are the same as human antibiotics so the names are most likely familiar.


"Amoxicillin is the leading feline antibiotic," according to This cousin to penicillin comes in pill or liquid suspension form, making it easy to administer the drug orally to the cat. Side effects of amoxicillin include vomiting (giving the medication with food may prevent this side effect), diarrhoea, excessive salivation and loss of appetite. In rare cases, amoxicillin may also cause liver disease. Amoxicillin should not be given to cats that are allergic to penicillin products or felines with kidney or heart disease.


Cephalexin is the brand name for antibiotics of the cephalosporin class. Cephalosporin antibiotics are commonly prescribed for skin infections, infections of the respiratory or urinary tracts and infections in the bone. Cephalexin comes in liquid suspension or "gummie" chews, and may cause the cat to lose its appetite, vomit or have diarrhoea and high fevers. Cats allergic to penicillin should not take Cephalexin. It may also be dangerous to pregnant or nursing cats, epileptic cats or cats that suffer from kidney disease.


This quinolone class antibiotic comes in pill form and has a very bitter taste; convincing a finicky feline to take this oral antibiotic is tough. Along with the common side effects of vomiting, diarrhoea and reduced appetite, enrofloxacin also hosts more serious side effects such as disorientation, depression, anxiety and seizures. As such, cats with epilepsy or other central nervous system disorders should avoid enrofloxacin. The oral antibiotic can also cause blindness, crystals in the cat's urine and obsessive behaviour.


Tetracycline should be taken on an empty stomach even though it can cause nausea and vomiting. Cats can be administered this antibiotic orally through liquid suspension, and generic formulas are available. In addition to the unwanted nausea, a feline may also suffer from hair loss, photosensitivity resulting in blisters on the skin, fever and loss of appetite. Tetracycline may permanently stain a kitten's teeth. Left over tetracycline should not be saved, as old medication might cause severe kidney damage.

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