# Chloramphenicol: veterinary dose and monograph

> Chloramphenicol is a veterinary antibiotic. Broad-spectrum bacteriostatic with excellent tissue / CNS / eye / prostate penetration and intracellular activity. Indications include multidrug-resistant soft-tissue and urinary infections; CNS / ocular / prostatic infections (deep penetration); resistant enterococcal and anaerobic infections. This monograph lists 14 reference doses for dogs, cats, horses, birds, rabbits and ferrets and 8 more species, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/chloramphenicol · Last reviewed: 2026-10-01

## 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

*Chloramphenicol doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Resistant susceptible infection | 40–50 mg/kg | PO | q8h | — |

- 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

*Chloramphenicol doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Resistant susceptible infection | 12.5–20 mg/kg | PO | q12h | — |

- 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

*Chloramphenicol doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection (adult) | 35–50 mg/kg | PO | q6–8h | — |

- 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

*Chloramphenicol doses for birds*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 50–80 mg/kg | IM | q8–12h | — |

- 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

*Chloramphenicol doses for rabbits*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection (SAFE in rabbits) | 30–50 mg/kg | PO | q8–24h | — |

- 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

*Chloramphenicol doses for ferrets*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Proliferative colitis / susceptible infection | 50 mg/kg | PO | q12h | — |

- 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

*Chloramphenicol doses for guinea pigs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection / pneumonia | 30–50 mg/kg | PO | q12h | — |

- 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

*Chloramphenicol doses for reptiles*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20–50 mg/kg | IM | q24h | — |

- 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

*Chloramphenicol doses for chinchillas*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 30–50 mg/kg | PO | q12h | — |

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

### Hamsters

*Chloramphenicol doses for hamsters*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20–50 mg/kg | SC | q6–12h | — |

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

### Rats

*Chloramphenicol doses for rats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20–50 mg/kg | SC | q6–12h | — |

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

### Mice

*Chloramphenicol doses for mice*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20–50 mg/kg | SC | q6–12h | — |

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

### Gerbils

*Chloramphenicol doses for gerbils*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20–50 mg/kg | SC | q6–12h | — |

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

### Hedgehogs

*Chloramphenicol doses for hedgehogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 30–50 mg/kg | PO | q12h | — |

- 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

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

> **Caution:** 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

> **Caution:** 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.

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## Frequently asked questions

### What is the dose of Chloramphenicol for dogs?

Reference doses for Chloramphenicol in dogs: 40–50 mg/kg PO q8h (Resistant susceptible infection). Confirm against the label and the patient before use.

### What is the dose of Chloramphenicol for cats?

Reference doses for Chloramphenicol in cats: 12.5–20 mg/kg PO q12h (Resistant susceptible infection). Confirm against the label and the patient before use.

### What is the dose of Chloramphenicol for horses?

Reference doses for Chloramphenicol in horses: 35–50 mg/kg PO q6–8h (Susceptible infection (adult)). Confirm against the label and the patient before use.

### When should Chloramphenicol not be used?

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

### What are the side effects of Chloramphenicol in animals?

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

## Sources

- Plumb's Veterinary Drug Handbook
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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VetMasterJi is a clinical decision-support and education platform for veterinary professionals and students. It does not provide veterinary advice, diagnosis or treatment for specific animals. All drug doses, calculators and differentials are references that must be independently verified before clinical use; the attending registered veterinarian remains solely responsible for every clinical decision.