Enrofloxacin is a prescription antibiotic used in dogs to treat bacterial infections of the skin, urinary tract, and respiratory system. Sold under the brand name Baytril, it belongs to a class of antibiotics called fluoroquinolones, which work by disrupting the enzymes bacteria need to copy and repair their DNA. This makes it effective against a broad range of bacteria, but it’s typically reserved for infections that don’t respond well to milder antibiotics.
FDA-Approved Uses in Dogs
The FDA has approved enrofloxacin for three categories of bacterial infections in dogs:
- Skin infections: wounds and abscesses caused by common bacteria including E. coli, Klebsiella, Proteus, and Staphylococcus aureus
- Respiratory infections: pneumonia, tonsillitis, and rhinitis (nasal inflammation) caused by E. coli and Staph aureus
- Urinary tract infections: bladder infections (cystitis) caused by E. coli, Proteus, and Staph aureus
Veterinarians sometimes prescribe enrofloxacin off-label for other types of infections, including ear infections and bone infections, particularly when bacterial culture results show the bacteria involved are susceptible to it. Because fluoroquinolones are considered important antibiotics that should be used judiciously to slow the development of resistant bacteria, many vets treat enrofloxacin as a second-line option rather than a first choice. Your vet may run a culture and sensitivity test before prescribing it to confirm it’s the right fit.
How It’s Given
Enrofloxacin comes in chewable flavored tablets (Baytril Taste Tabs) in several strengths: 22.7 mg, 68 mg, and 136 mg. The standard dose range is 5 to 20 mg per kilogram of body weight per day, given either as a single daily dose or split into two doses 12 hours apart. Your vet will determine the exact dose based on the type and severity of the infection.
An injectable form also exists, typically used as a single starting dose of 2.5 mg/kg followed by oral tablets 12 hours later.
If your dog takes any supplements or medications containing calcium, iron, magnesium, or aluminum, give the enrofloxacin at least two hours before or after those products. Antacids, Pepto-Bismol, and iron supplements can all reduce how much of the drug your dog actually absorbs. The rate of absorption may also be slightly more variable when given with food, though the total amount absorbed stays roughly the same.
How Long Treatment Lasts
Treatment duration depends on the infection. Uncomplicated urinary tract infections in dogs are typically treated with antibiotics for 7 to 14 days. Some research has explored shorter, higher-dose courses of enrofloxacin (3 days at 18 to 20 mg/kg) for simple UTIs, but this approach isn’t standard practice for most cases. Skin infections and respiratory infections generally require a full course of 10 to 30 days depending on severity. Your vet will likely want to recheck your dog or repeat lab work before stopping the medication to make sure the infection has fully cleared.
Side Effects to Watch For
The most common side effects involve the digestive system: vomiting, diarrhea, and loss of appetite. These are usually mild and may improve after the first day or two of treatment. Giving the medication with a small amount of food can help settle your dog’s stomach.
Less common but more serious effects can involve the nervous system. Some dogs experience dizziness, wobbliness, or in rare cases, seizures. Enrofloxacin has also been shown to alter heart rhythm in dogs, affecting how the heart’s electrical signals travel, which could increase the risk of abnormal heart rhythms. If your dog has a known seizure disorder or heart condition, your vet will likely choose a different antibiotic.
Age Restrictions for Puppies
Enrofloxacin can damage the cartilage in growing joints, which makes it unsafe for puppies. Dogs under 12 months of age should not receive this drug. For very large breeds that have a longer growth period, the cutoff extends to 18 months. This restriction exists because the cartilage in a young dog’s joints is still developing, and fluoroquinolones can interfere with that process, potentially causing lasting joint problems. If your puppy has an infection that seems to call for a strong antibiotic, your vet will select a safer alternative.
Drug Interactions
The most commonly cited interaction is with products that contain metal ions: aluminum, magnesium, calcium, and iron. These minerals bind to enrofloxacin and form complexes that the body can’t absorb. Sucralfate, a stomach-coating medication that contains aluminum, is frequently flagged as a concern. Interestingly, one veterinary study found that sucralfate did not significantly reduce the total absorption of enrofloxacin in fed dogs, though this doesn’t necessarily apply to all situations. The safest approach is still to separate the doses by at least two hours.
Enrofloxacin can also interact with certain anti-seizure medications and drugs that affect heart rhythm, so always let your vet know about everything your dog is currently taking, including over-the-counter supplements.