Chloramphenicol: veterinary dose and monograph

At a glance

Drug class

Antibiotic

Also known as

Chloromycetin, Phenicol

Species with doses

Dogs, Cats, Horses, Birds, Rabbits, Ferrets, Guinea pigs, Reptiles, Chinchillas, Hamsters, Rats, Mice, Gerbils and Hedgehogs

General dose range

12.5–50 mg/kg PO q8h (dog) / q12h (cat) — check the species tables for the indication

Routes

PO, IM, SC

Last reviewed

1 October 2026

Indications

• Multidrug-resistant soft-tissue and urinary infections
• CNS / ocular / prostatic infections (deep penetration)
• Resistant enterococcal and anaerobic infections

Chloramphenicol dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Resistant susceptible infection: Papich 5e: 40–50 mg/kg q8h PO. Plumb’s p.252: 40–50 mg/kg IV, IM, SC or PO q8h (Vaden & Papich 1995); systemic 50 mg/kg q6–8h for 3–5 days. Avoid in young, breeding or pregnant animals; dose-related marrow suppression with long courses. Humans: idiosyncratic aplastic anaemia — wear gloves. Prohibited in food-producing animals.

Cats

• Resistant susceptible infection: Papich 5e: 12.5–20 mg/kg q12h PO (or 50 mg per cat). Plumb’s p.252: 50 mg TOTAL per cat q8–12h (Vaden & Papich; Greene & Watson); USPC 25–50 mg/kg PO q12h. Cats are more prone to marrow suppression — keep courses short (≤14 days) and monitor CBC and appetite.

Horses

• Susceptible infection (adult): Papich 5e: 35–50 mg/kg q6–8h PO. Plumb’s p.252: 45–60 mg/kg PO q8h (USPC); foals 40–50 mg/kg PO q6–8h or succinate 25–50 mg/kg IV q4–8h (Brumbaugh 1999). Prohibited in food-producing animals; handlers should wear gloves.

Birds

• Susceptible infection: Plumb's p.253: succinate 50–80 mg/kg IM/IV 2–4×/day; palmitate suspension 75 mg/kg PO q8h (erratic PO absorption). Ratites 35–50 mg/kg ×3/day (not for food).

Rabbits

• Susceptible infection (SAFE in rabbits): Plumb's p.252 (Ivey & Morrisey 2000): 30–50 mg/kg PO/SC/IM/IV q8–24h. Unlike penicillins, chloramphenicol is SAFE in rabbits — a preferred rabbit antibiotic.

Ferrets

• Proliferative colitis / susceptible infection: Plumb's p.252 (Johnson 2006; Williams 2000): proliferative colitis (Lawsonia) 50 mg/kg PO q12h ×14–21 days; susceptible infections 50 mg/kg PO/SC/IM twice daily.

Guinea pigs

• Susceptible infection / pneumonia: Plumb's p.252: pneumonia 30–50 mg/kg PO q12h (Johnson 2006); succinate 20–50 mg/kg SC q6–12h.

Reptiles

• Susceptible infection: Plumb's p.253 (Lewbart 2001): sodium succinate 20–50 mg/kg IM/SC (or 30–50 mg/kg/day IV/IM) for up to 3 weeks. Good empiric first choice pending sensitivity.

Chinchillas

• Susceptible infection: Plumb's p.252 (Hayes 2000): 30–50 mg/kg PO/SC/IM q12h.

Hamsters

• Susceptible infection: Plumb's p.252: 20–50 mg/kg (succinate) SC q6–12h.

Rats

• Susceptible infection: Plumb's p.252: 20–50 mg/kg (succinate) SC q6–12h.

Mice

• Susceptible infection: Plumb's p.252: 20–50 mg/kg (succinate) SC q6–12h.

Gerbils

• Susceptible infection: Plumb's p.252 (Adamcak & Otten 2000): Gerbils/Guinea Pigs/Hamsters/Mice/Rats 20–50 mg/kg (succinate) SC q6–12h.

Hedgehogs

• Susceptible infection: Plumb’s p.252 (Smith 2000): hedgehogs 50 mg/kg PO q12h, or 30–50 mg/kg SC, IM, IV or IO q12h.

Contraindications

ABSOLUTELY PROHIBITED in food-producing animals (illegal residue, human aplastic anaemia). Severe hepatic impairment. Neonates (immature glucuronidation). Bone-marrow suppression. Concurrent myelosuppressive drugs.

Species-specific warnings

Cattle: ILLEGAL in any food-producing animal — zero-tolerance residue. Never use in cattle, goats, sheep, pigs or poultry.

Cats: Cats are especially sensitive — anorexia and myelosuppression at standard doses; keep courses short and monitor CBC.

Adverse effects

• Dose-dependent reversible bone-marrow suppression
• Anorexia (especially cats — common dose-limiting effect)
• Hind-limb weakness in cats (high dose / prolonged use)
• GI upset

Drug interactions

• Potent hepatic enzyme inhibitor — prolongs phenobarbital, propofol, pentobarbital and other hepatically cleared drugs
• Antagonises bactericidal beta-lactams / aminoglycosides (bacteriostatic interference)

Pregnancy and lactation

Avoid in pregnancy and neonates — immature hepatic conjugation causes accumulation (grey-baby-type toxicity).

Toxicity and overdose

Plumb's: because of the potential for serious bone marrow toxicity, large overdoses should be managed by emptying the gut using standard decontamination protocols. Two distinct marrow effects exist — a reversible, dose-dependent suppression in treated animals, and the idiosyncratic non-dose-related human aplastic anaemia that underlies the ban on chloramphenicol in food-producing animals worldwide. CATS are notably susceptible to prolonged effects because of limited glucuronidation; keep feline courses short and watch for anorexia and cytopenias. Humans handling the drug should avoid skin contact.

Clinical pearls

• Reserve for culture-confirmed resistant infections where penetration matters (CNS, eye, prostate)
• Warn owners to wear gloves and avoid crushing tablets — human aplastic anaemia is idiosyncratic and dose-independent
• Strong enzyme inhibitor — reduce doses of concurrently metabolised drugs

Mechanism of action

Plumb's p.250: binds the 50S ribosomal subunit and prevents bacterial protein synthesis — usually bacteriostatic, but bactericidal at higher concentrations or against very susceptible organisms. Erythromycin, clindamycin, lincomycin and tylosin bind the SAME site, so those combinations are antagonistic. Uniquely among them, chloramphenicol also has affinity for the mitochondrial ribosomes of rapidly dividing mammalian cells (notably bone marrow), which is the mechanism of its reversible, dose-related marrow suppression — distinct from the idiosyncratic, non-dose-related aplastic anaemia seen in humans. Wide gram-positive and gram-negative spectrum; highly lipid-soluble, so it crosses the blood-brain and blood-prostate barriers.

Formulations and products

• Chloramphenicol 250 mg tablet
• Chloramphenicol 500 mg tablet
• Chloramphenicol sodium succinate 100 mg/mL injection

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

Other antibiotics

• Ceftiofur
• Ceftriaxone
• Cefuroxime
• Cephalexin
• Ciprofloxacin
• Clarithromycin
• Clindamycin
• Cloxacillin

Frequently asked questions