Ciprofloxacin

Ciprofloxacin is a fluoroquinolone antibacterial with activity against susceptible gram-negative bacteria and selected gram-positive organisms. It is a human medicinal product used extra-label in veterinary practice, principally in companion animals. Oral absorption in dogs and cats is variable, making its clinical exposure less predictable than that of several veterinary fluoroquinolones.

Group

Fluoroquinolone antibacterial

Mechanism of Action

Ciprofloxacin inhibits bacterial DNA gyrase and topoisomerase IV, enzymes required for DNA supercoiling, replication and separation of daughter chromosomes. Stabilization of enzyme–DNA cleavage complexes disrupts DNA processing and leads to bacterial death. Its activity is concentration dependent and can persist after concentrations decline. The spectrum includes susceptible Enterobacterales and Pseudomonas aeruginosa, with organism-specific resistance determining activity.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	25 mg/kg	PO	Every 24 h
Bacterial infections	15 mg/kg	IV	Every 24 h	Dilute and infuse over 30 minutes; watch for anaphylactoid reactions.
Alternative bacterial infection treatment	5–15 mg/kg	PO	Every 12 h	Historical regimen; variable oral absorption can cause inadequate exposure. Use susceptibility and clinical response rather than human breakpoints.
Urinary tract infection	10 mg/kg	PO	Every 24 h	Up to 14 days; Historical course 7–14 days; confirm achievable exposure and susceptibility.
Skin or soft-tissue infection	10–15 mg/kg	PO	Every 24 h	Up to 14 days
Bone or systemic bacterial infection	20 mg/kg	PO	Every 24 h	Up to 14 days
Pyoderma	11 mg/kg	PO	Every 12 h

Cats

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	20 mg/kg	PO	Every 24 h
Bacterial infections	10 mg/kg	IV	Every 24 h	Dilute and infuse over 30 minutes.
Susceptible gram-negative infection	10 mg/kg	PO	Every 12 h	Alternative discussed in the pharmacokinetic section; low oral absorption limits reliability.
Alternative bacterial infection treatment	5–15 mg/kg	PO	Every 12 h	Historical regimen; variable oral absorption can cause inadequate exposure. Use susceptibility and clinical response rather than human breakpoints.

Ferrets

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	5–15 mg/kg	PO	Every 12 h

Rabbits

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	5–20 mg/kg	PO	Every 12 h
Pasteurellosis	15–20 mg/kg	PO	Every 12 h	Mild disease courses are at least 14 days in the cited regimen; chronic infection requires an individualized plan, sometimes much longer.

Chinchillas

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	7–20 mg/kg	PO	Every 12 h

Gerbils

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	7–20 mg/kg	PO	Every 12 h

Guinea pigs

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	7–20 mg/kg	PO	Every 12 h

Hamsters

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	7–20 mg/kg	PO	Every 12 h

Mice

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	7–20 mg/kg	PO	Every 12 h

Rats

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	7–20 mg/kg	PO	Every 12 h

Birds

Use / stage	Dose	Route	Schedule	Instructions
Gram-negative infection	20–40 mg/kg	PO	Every 12 h	Using crushed tablets; shake suspension thoroughly before each dose.
Alternative bacterial infection treatment	10–15 mg/kg	PO	Every 12 h

Ratites

Use / stage	Dose	Route	Schedule	Instructions
Bacterial infections	3–6 mg/kg	PO	Every 12 h

Indications

Extra-label treatment of selected susceptible gram-negative urinary tract infections in dogs and cats.
Treatment of selected susceptible bacterial respiratory, skin and soft-tissue infections in companion animals when adequate exposure is achievable.
Treatment of selected Pseudomonas aeruginosa infections with demonstrated ciprofloxacin susceptibility.

Contraindications

Avoid use in growing animals because of cartilage injury risk.
Use cautiously with seizure disorders or renal impairment.
Not recommended in horses.
Do not use in food-producing animals where prohibited.

Interactions

Aluminum, calcium, iron and zinc reduce absorption or cause incompatibility.
May increase theophylline exposure.
Separate sucralfate, iron, zinc and multivalent-cation antacids by at least two hours from oral ciprofloxacin.
Warfarin effects or methotrexate exposure may increase; quinidine can increase cardiac risk.
Cyclosporine renal toxicity may increase; glyburide can cause marked hypoglycemia and phenytoin levels may change.
Nitrofurantoin can oppose fluoroquinolone activity; probenecid can increase ciprofloxacin exposure.

Adverse effects

Vomiting, nausea and diarrhea
CNS toxicity with excessive exposure
Arthropathy in immature animals
Anaphylactoid reactions and hypotension during IV infusion

Preparations

Preparation	Form	Strength	Route
Ciprofloxacin 100 mg tablet	Tablet	100 mg / tablet	PO
Ciprofloxacin 250 mg tablet	Tablet	250 mg / tablet	PO
Ciprofloxacin 500 mg tablet	Tablet	500 mg / tablet	PO
Ciprofloxacin 750 mg tablet	Tablet	750 mg / tablet	PO
Ciprofloxacin 50 mg/mL oral liquid	Oral Liquid	50 mg / mL	PO
Ciprofloxacin 100 mg/mL oral liquid	Oral Liquid	100 mg / mL	PO
Ciprofloxacin 10 mg/mL injection	Injection	10 mg / mL	IV
Ciprofloxacin 2 mg/mL injection	Injection	2 mg / mL	IV

Monitoring and Administration

Culture and interpret susceptibility against achievable exposure rather than applying human thresholds automatically. Equine oral absorption is very poor.

Dilute concentrated injection to 1–2 mg/mL and infuse over 30 minutes; monitor for hypotension or arrhythmia. Do not co-infuse other medications.

Keep solutions away from multivalent cations. Aqueous 0.5–2 mg/mL preparations have described stability up to 14 days.

Maintain hydration because crystalluria can occur. Growing large or giant dogs may remain susceptible to cartilage injury beyond the age applicable to smaller breeds.

Do not substitute extended-release human tablets for immediate-release veterinary regimens without evidence for that preparation.