Baytril(®) (enrofloxacin) is an antibiotic medicine given to dogs for the treatment of susceptible bacterial infections. The medicine works well against both gram-positive and gram-negative strains of bacteria, but is ineffective at treating anaerobes, and is not as efficient as other options for treating Streptococcal infections. In most cases it is safe and does not cause serious complications, though there is a risk of cartilage abnormalities in puppies.

My dog is allergic to penicillin, can they still use this medicine?

Baytril is not a penicillin antibiotic, it is a fluoroquinolone antibiotic. Please be aware, however, that sensitivity to this type of antibiotic is also possible, and dogs who have had bad reactions in the past to other fluoroquinolones (e.g. Zeniquin) are likely unsuitable for treatment.

Recommended Dosage

For safety reasons, do not begin treating your dog without a vet’s approval and a diagnosis of bacterial infection. Always follow your vet’s recommended dosage and treatment plan.

Enrofloxacin can be administered orally or injected intravenously, though using injectable forms of the drug in household pets is controversial. Generally when treating most infections in dogs the dosage ranges from 2.28 mg/lb to 9 mg/lb (roughly 5 to 20 mg/kg) given orally once daily, which can be split in half for twice-daily administration. The chart below illustrates an average 5 mg/lb dosage:

Typical dosage of Baytril for dogs

When treating different infections, different dosages may be recommended. Please see the table below:

To treat infections of the…

Method of administration


SkinOral1.14 – 2.27 mg/lb every 12 hours for 1 to 2 weeks
Respiratory tractOral2.27 – 4.5 mg/lb every 24 hours for 1 to 12 weeks

Antibiotics are not effective in the treatment of viruses and should not be used unless bacteria is determined to be the cause of symptoms.

Note: Do not discontinue use as soon as symptoms clear, complete the full course to prevent the infection from returning. In most cases the drug will not be used for more than 30 consecutive days.

Ear Infections

Baytril Otic is a liquid emulsion used to treat susceptible ear infections. This medicine contains enrofloxacin with the addition of silver sulfadiazine. To find out more about this medicine and how it can be used to treat otitis externa please click this link.

Example: In general a 20 pound dog would receive 100 milligrams of enrofloxacin each day.

Safety Information

There are many drugs which can interact with Baytril which means it’s important to disclose any other medicine and supplements your dog is taking to your vet prior to starting treatment. Drugs which can interact with this medicine includes some other antibiotics, zinc, iron, antacids, warfarin and more. There are also various medical conditions which could be aggravated through the use of enrofloxacin, so please also disclose any of your dog’s existing medical conditions to the vet.

Avoid giving this medicine to small and medium dog breeds aged 2 to 8 months. In larger breeds, it’s safer to wait beyond this period of time before beginning treatment as their growth phase can last longer. In terms of injection, subcutaneous administration could be painful because of the medicine’s acidity and undiluted IV injections increase the chance of severe reactions with the possibility of placing stress upon the heart.

Pregnancy, nursing and breeding: It’s advised that pregnant and nursing animals do not take Baytril or any other fluoroquinolone antibiotics. For male breeding dogs the use of this drug is fine.

Guidelines For Use

As mentioned above, it’s important to disclose to your vet any medicine/supplements your dog is taking and any existing medical conditions. The following lists guidelines for the safe use of enrofloxacin:

  • Avoid use in puppies from 2 to 8 months of age (wait longer for larger breeds, see a vet)
  • Lower doses than those recommended should be used in dogs with kidney and liver problems
  • Provide plenty of water to maintain hydration during treatment

Complete the full course of treatment recommended to you by your vet, do not stop using the medicine based on the improvement of symptoms.

What’s It Used For?

Baytril is a veterinary antibiotic drug and is used to treat susceptible bacterial infections in animals. It is not used to fight anaerobic infections, and is rarely used against Streptococci due to limited efficiency.

Side Effects

During treatment the following adverse effects are possible:

More Common

  • Vomiting
  • Weight loss


  • Loss of coordination
  • Seizures
  • Fatigue
  • Anxiety
  • Depression

In puppies, cartilage damage is also possible. It’s recommended that owners report any uncomfortable adverse effects to the vet, and seek immediate veterinary attention for any serious reactions.


Overdoses of Baytril rarely cause problems beyond anorexia and vomiting. However, the rarer effects listed above such as loss of coordination and seizures may occur in some dogs. In studies, death occured in some cases where 25x the recommended dose was given for 11 consecutive days. Despite its relative safety unless extremely high amounts are used, if you for any reason suspect an overdose you should ring the vet for advice.


Dr. R. Hardie
Plumb’s Veterinary Drug Handbook (sixth edition)