Fluoroquinolone Antibiotics

Fluoroquinolone Antibiotics


Fluoroquinolones are powerful antibiotics that are commonly prescribed for pets.  They are used to treat infections of the skin, bladder, ears, kidneys, lungs (pneumonia), and prostate. Fluoroquinolones are prescribed many other types of infections as well.

The most frequently used fluoroquinolones are enrofloxacin (Baytril®), ciprofloxacin (also known as cipro), orbifloxacin (Orbax®), and marbofloxacin (Zeniquin®).


Fluoroquinolones are most commonly administered orally as a pill.   Liquid formulations may be available through your veterinarian or through a special compounding pharmacy.

Baytril® is available as an otic suspension that is applied directly to the ears to treat ear infections.

Injectable fluoroquinolones are frequently used by veterinarians on hospitalized pets.

Side Effects

Like all antibiotics, gastrointestinal upset (nausea, diarrhea, vomiting, or loss of appetite) is the leading side effect of fluoroquinolones.  The risk of side effects may be reduced by giving the medication with food.  Ask your veterinarian whether this is appropriate for your pet.

The gastrointestinal side effects of antibiotics generally get worse over time if the medicine is not discontinued.  Therefore, if you suspect that your pet is experiencing side effects, contact your veterinarian immediately.  Do not discontinue any antibiotic without first consulting a veterinarian.

In very rare instances, cats receiving high doses of Baytril® have developed severe, irreversible vision problems.  This adverse reaction is believed to be unlikely at lower doses.

Puppies (and less often kittens) who receive fluoroquinolones while they are growing may develop defects in the cartilage of their joints.  Fluoroquinolones should be avoided in growing animals.


Pets should be monitored for side effects and for resolution of symptoms.  Unless otherwise instructed by a veterinarian, pets should continue to take the medication until the entire course has been completed.

Long-term (greater than 14 days) use of fluoroquinolones is uncommon.  Any pet that receives long-term medications may require periodic blood or urine testing.

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The contents of this page are provided for general informational purposes only. Under no circumstances should this page be substituted for professional consultation with a veterinarian.