Moxifloxacin in Veterinary Medicine: Uses, Dosage, and Contraindications in Dogs and Cats

Introduction

Moxifloxacin is a broad-spectrum fluoroquinolone antibiotic commonly used in human medicine, but it has potential veterinary applications as well. While it is not FDA-approved for veterinary use, some veterinarians may prescribe it off-label for treating bacterial infections in dogs and cats. This article explores the uses, dosage, and contraindications of moxifloxacin in veterinary medicine.

Mechanism of Action

Moxifloxacin works by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes essential for bacterial DNA replication. This action leads to bacterial cell death, making it effective against a wide range of Gram-positive and Gram-negative bacteria, including some anaerobes and atypical pathogens.

Uses of Moxifloxacin in Dogs and Cats

Moxifloxacin is primarily used for treating infections caused by bacteria resistant to other antibiotics. Some common applications include:

• Respiratory infections – Effective against bacterial pneumonia, bronchitis, and other lower respiratory tract infections.
• Urinary tract infections (UTIs) – Used in cases where first-line antibiotics are ineffective.
• Skin and soft tissue infections – Treats deep pyoderma, abscesses, and wounds infected with susceptible bacteria.
• Ophthalmic infections – Moxifloxacin ophthalmic solution is used to manage bacterial conjunctivitis, keratitis, and corneal ulcers.
• Otitis externa and media – Can be used in some cases of bacterial ear infections.
• Gastrointestinal infections – Effective against some enteric pathogens, though its use is limited in these cases.

Dosage of Moxifloxacin for Dogs and Cats

Moxifloxacin is available in oral (tablets and suspension), injectable, and ophthalmic formulations. Since its veterinary use is off-label, dosages may vary depending on the veterinarian’s discretion and the severity of the infection.

Oral Dosage (Tablets or Suspension)

• Dogs: 5–10 mg/kg once daily
• Cats: 5–10 mg/kg once daily

Injectable Dosage

• Dogs and Cats: 5–10 mg/kg IV or SC once daily (reserved for severe infections)

Ophthalmic Solution

• Dogs and Cats: 1–2 drops in the affected eye(s) every 6–12 hours, depending on severity

Duration of treatment typically ranges from 5 to 14 days, depending on the condition and response to therapy.

Contraindications and Precautions

While moxifloxacin is a powerful antibiotic, it should be used with caution in veterinary medicine.

Contraindications

• Growing puppies and kittens – Fluoroquinolones can cause cartilage damage in young animals.
• Pregnant or lactating animals – Safety has not been well established.
• Seizure-prone animals – May lower the seizure threshold, worsening neurological conditions.
• Pre-existing kidney or liver disease – Requires dose adjustments or alternative therapy.

Potential Side Effects

• Gastrointestinal upset – Vomiting, diarrhea, or loss of appetite.
• Neurological effects – Tremors, dizziness, or ataxia in sensitive animals.
• Joint toxicity – Cartilage damage in young animals.
• Retinal toxicity in cats – Though less common with moxifloxacin compared to enrofloxacin, caution is advised.

Drug Interactions

• Antacids and calcium supplements – Reduce absorption of moxifloxacin.
• NSAIDs – May increase the risk of seizures.
• Corticosteroids – May exacerbate tendon damage.
• Theophylline – May lead to increased toxicity.

Conclusion

Moxifloxacin is a potent fluoroquinolone antibiotic that may be used off-label in veterinary medicine for treating bacterial infections in dogs and cats. Due to its potential side effects and contraindications, it should only be prescribed by a veterinarian after careful consideration of risks and benefits. Always follow the prescribed dosage and duration to prevent antibiotic resistance.