Enrofloxacin (Baytril) for Dogs and Cats

Medically Reviewed by Kathleen Claussen, DVM on October 13, 2024
Written by Joshua Conrad, PharmD
6 min read

Enrofloxacin (Baytril) is a medicine used to treat certain infections in dogs and cats. It is also used “extra-label” or “off-label” for other infections in dogs and cats. This means that there may be evidence of safe and effective use but the FDA has not approved that use.

Enrofloxacin is classified as a fluoroquinolone antibiotic that has a broad spectrum of activity, meaning it is effective against many types of bacteria. It is especially good against Gram-negative bacteria that other antibiotics can’t kill.  

It is best to save this broad-spectrum antibiotic for the infections that other antibiotics can’t fight. This is one step in limiting antibiotic resistance, which means that the bacteria can withstand antibiotics.

In dogs, enrofloxacin is approved by the FDA for oral and intramuscular (injection into the muscle) use. It can also be used extra-label in dogs by injection subcutaneously (under the skin) or intravenously (into a vein), but this is controversial. In cats, only the oral form is FDA-approved, but the injectable form is sometimes used extra-label either intramuscularly or intravenously.

Enrofloxacin is available by prescription from your veterinarian or with a veterinary prescription. It is available in tablet, flavored chewable tablet, and injectable forms. Contact your veterinary compounding pharmacy for alternative dosing options.

Enrofloxacin is given by mouth as a tablet or chewable tablet. It can also be given as an injection at the veterinary clinic. It is usually given once or twice daily for the length of the prescribed treatment. It is important to finish all of the prescribed antibiotic unless otherwise directed by your veterinarian, even if your pet seems to be better. 

Enrofloxacin may be given with or without food. If stomach upset occurs, try giving it with food or a treat, but not with any dairy products such as milk or cheese. Do not crush the non-chewable tablets.

Always follow your veterinarian’s directions for giving medicines to animals. Remember to tell your veterinarian about any medicines, vitamins, supplements, or herbal therapies that you are giving your pet. Talk to your veterinarian before stopping any pet medicines.  

  • Enrofloxacin is a broad-spectrum antibiotic, meaning that it is effective against many types of bacteria.
  • Enrofloxacin is specifically formulated for animals and is more well-studied in animals than human fluoroquinolones like ciprofloxacin.

You and your veterinarian should monitor your pet for improvement of their condition, as well as for side effects of the medicine. Before starting your pet on enrofloxacin, your veterinarian may perform a test to confirm that your pet is taking the best antibiotic for their condition. This is called a bacterial culture and sensitivity test. The results of the test can take several days to receive, but the veterinarian may want your pet to start taking the medicine before the results are back. They may wish to change the medicine when the results return.

In cats, your veterinarian may monitor kidney function with blood tests.

Do not use enrofloxacin in animals that are allergic to it or to other medicines called fluoroquinolones.  Use it with caution in pregnant dogs and in cats that are breeding, pregnant, or nursing. Use enrofloxacin with caution in animals that have kidney disease, especially cats. Use with caution in animals that are not fully mature since it can affect the growing cartilage.

Side effects occur in 1% to 2% of dogs taking enrofloxacin. The side effects are usually related to the gastrointestinal system (stomach and intestines) and include:

  • Vomiting
  • Decreased or no appetite
  • Loose stool or diarrhea 

Enrofloxacin is classified as a fluoroquinolone. These medicines have been associated with tears of tendons, which are the tissues that connect muscles to bones. The risk is higher in animals that have had torn tendons before and with strenuous physical activity.

Enrofloxacin can also make your pet’s bare skin (such as on the nose) more sensitive to sunlight. Limit your pet’s time in the direct sunlight while getting enrofloxacin.

Less common side effects include kidney problems, liver problems, seizures, difficulty walking, depression, tiredness, and nervousness.

If side effects are severe, worsen, or continue with enrofloxacin, stop the medicine and contact your veterinarian. Your veterinarian will discuss treatment options depending on the side effects and may recommend switching to a different antibiotic. Your veterinarian may recommend starting a probiotic to help change your pet’s gut flora, which are the “good” bacteria that live in your pet’s intestines.

If you think that your pet is having a serious side effect or may have been overdosed, call your veterinary clinic immediately. If it is outside of regular office hours, you may contact a local emergency veterinary hospital or an animal poison control center. Note that fees may apply for emergency consultation.

You can reach the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.

Using multiple medicines can sometimes change how your pet’s medicines work or increase your pet’s risk for serious side effects. Always tell your veterinarian about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements that your pet is using.

In particular, make sure that you discuss if your pet is using any of the following before using enrofloxacin.

Antacids. Antacids such as Maalox and Mylanta are used to treat stomach upset. Some of these contain aluminum, calcium, or magnesium.  When given with enrofloxacin, these antacids decrease the absorption of enrofloxacin, which can cause it to not work as well.  Separate antacids and enrofloxacin doses by at least two hours.

Corticosteroids. When enrofloxacin is used at the same time as corticosteroids such as dexamethasone or prednisone, there is an increased risk of tendon rupture.

Diabetes medicines. When enrofloxacin is used with diabetes medicines, including insulin, there is an increased risk of low blood sugar.

Iron. When given with enrofloxacin, iron supplements can decrease the absorption of enrofloxacin, which can cause it to not work as well. Separate iron supplement and enrofloxacin doses by at least two hours.

Warfarin. Warfarin is an anticoagulant medicine that is commonly used as a blood thinner to prevent blood clots from forming in the bloodstream. There is a greater risk for bleeding when this medicine is used with enrofloxacin.

Zinc. When given with enrofloxacin, zinc supplements can decrease the absorption of enrofloxacin, which can cause it to not work as well. Separate zinc supplement and enrofloxacin doses by at least two hours.

In addition, certain medicines can cause an abnormal heart rhythm called QT prolongation. Taking these medicines with enrofloxacin can increase this risk, which can be serious. Talk with your veterinarian to ensure they know all medicines that your pet is taking.

This may not be a complete list of medicines that can interact with enrofloxacin. Always check with your veterinarian.

  • Keep enrofloxacin out of reach of children.
  • Wash your hands after giving enrofloxacin to your dog or cat.
  • Do not handle enrofloxacin if you are allergic to it or to any medicine that is classified as a fluoroquinolone.

To prevent accidental swallowing of the tablets, the package should be stored in a secure location out of reach of the pet. If you think your pet has taken more enrofloxacin than prescribed, call your veterinarian or veterinary emergency clinic immediately.

If your pet misses a dose, you can give that dose if it is close to the original scheduled time.  If it is closer to the next dosing time, skip the missed dose completely and give the next dose at the correct time.  Do not double the dose of the medicine, but make sure that the pet finishes the whole course of the prescription.

Enrofloxacin tablets should be protected from moisture and light.  It should be stored at room temperature.  Follow the instructions for storage on the package if the enrofloxacin is compounded.