# Procaine Penicillin G: veterinary dose and monograph

> Procaine Penicillin G is a veterinary antibiotic. A long-acting (DEPOT) repository form of penicillin G in which procaine slows absorption from the IM site, giving sustained (~24 h) therapeutic levels from a once-daily injection — the practical everyday penicillin for food animals and… Indications include susceptible Gram-positive infections (Streptococcus, Clostridium, Actinomyces, Erysipelas); leptospirosis; blackleg/clostridial disease; foot rot; strangles (Streptococcus equi); wound/soft-tissue and respiratory infections (susceptible organisms). This monograph lists 9 reference doses for dogs, cats, cattle, horses, goats and sheep and 3 more species, each with route, frequency and source, plus meat and milk withdrawal periods for food animals.

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

## At a glance

- **Drug class:** Antibiotic
- **Also known as:** Procaine benzylpenicillin, PPG, Fortified procaine penicillin
- **Species with doses:** Dogs, Cats, Cattle, Horses, Goats, Sheep, Pigs, Rabbits and Ferrets
- **Routes:** IM, SC
- **Last reviewed:** 1 October 2026

## Indications

- Susceptible Gram-positive infections (Streptococcus, Clostridium, Actinomyces, Erysipelas)
- Leptospirosis; blackleg/clostridial disease; foot rot; strangles (Streptococcus equi)
- Wound/soft-tissue and respiratory infections (susceptible organisms)
- Everyday food-animal/equine penicillin therapy (once-daily depot)

## Procaine Penicillin G 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

*Procaine Penicillin G doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20000–40000 mg/kg | IM | q12–24h | — |

- Susceptible infection: UNITS/kg. Plumb’s p.945 (Greene 2006): 20,000–40,000 U/kg IM or SC q12–24h; leptospiraemia 25,000–40,000 U/kg q12–24h for 14 days, then doxycycline for the carrier state (Ross & Rentko). Not in Papich 5e.

### Cats

*Procaine Penicillin G doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Soft-tissue / orthopaedic infection | 20000–40000 mg/kg | IM | q8–12h | — |

- Soft-tissue / orthopaedic infection: UNITS/kg. Plumb’s p.945 (Greene 2006): soft tissue 20,000 U/kg IM or SC q12h; orthopaedic 20,000–40,000 U/kg IM q8h; Actinomyces 50,000–100,000 U/kg IM/SC q12h.

### Cattle

*Procaine Penicillin G doses for cattle*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Susceptible Gram-positive infection | 10000–40000 mg/kg | IM | q12–24h | — | Withdrawal NOT established — treat as extra-label |

- Susceptible Gram-positive infection: UNITS/kg. Plumb’s p.945: 25,000 U/kg once daily, twice daily for moderately susceptible bacteria (Gunn); 40,000 U/kg IM once daily (Howard); 10,000–20,000 U/kg IM q12–24h (Jenkins); BRD 66,000 U/kg IM/SC once daily with a 20-day slaughter withdrawal (Hjerpe). Label doses are lower (≈6,600 U/kg) and label withdrawals apply only to them — higher extra-label doses need FARAD-extended meat and milk withdrawals. Aspirate before injecting; never IV. Calves, clostridial abomasitis: 10,000–20,000 U/kg PO q12–24h for 1–4 days.

### Horses

*Procaine Penicillin G doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Strangles / susceptible infection | 22000–44000 mg/kg | IM | q12h | — |

- Strangles / susceptible infection: UNITS/kg. Plumb’s p.945: 22,000–44,000 U/kg IM q12h (Whittem); strangles 22,000 U/kg IM q12h early in infection (Foreman); foals 22,000–50,000 U/kg IM q12h. Aspirate first — intravascular procaine causes excitement/collapse. Watch for colitis.

### Goats

*Procaine Penicillin G doses for goats*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Susceptible infection (extra-label) | 10000–40000 mg/kg | IM | q12–24h | — | Withdrawal NOT established — treat as extra-label |

- Susceptible infection (extra-label): UNITS/kg. Plumb’s p.945 (cattle and other ruminants): 10,000–40,000 U/kg IM q12–24h. No goat label — obtain a FARAD withdrawal before slaughter or milk use.

### Sheep

*Procaine Penicillin G doses for sheep*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Foot rot / clostridial disease | 10000–40000 mg/kg | IM | q24h | — | Withdrawal NOT established — treat as extra-label |

- Foot rot / clostridial disease: UNITS/kg. Plumb’s p.945 (cattle and other ruminants): 10,000–40,000 U/kg IM q12–24h. Label withdrawal applies only at the label dose; higher doses need a FARAD withdrawal. Aspirate before injecting.

### Pigs

*Procaine Penicillin G doses for pigs*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Erysipelas / susceptible infection | 6600–40000 mg/kg | IM | q24h | — | Withdrawal NOT established — treat as extra-label |

- Erysipelas / susceptible infection: UNITS/kg. Plumb’s p.945: 40,000 U/kg IM once daily (Howard); 6,600 U/kg IM once daily for no more than 4 days (Wood — label dose). Label withdrawal applies only at the label dose; obtain FARAD advice for higher doses.

### Buffalo

No buffalo-specific doses are on file, so buffalo are dosed as cattle.

*Procaine Penicillin G doses for buffalo*

| Indication | Dose | Route | Frequency | Duration | Withdrawal |
| --- | --- | --- | --- | --- | --- |
| Susceptible Gram-positive infection | 10000–40000 mg/kg | IM | q12–24h | — | Withdrawal NOT established — treat as extra-label |

- Susceptible Gram-positive infection: UNITS/kg. Plumb’s p.945: 25,000 U/kg once daily, twice daily for moderately susceptible bacteria (Gunn); 40,000 U/kg IM once daily (Howard); 10,000–20,000 U/kg IM q12–24h (Jenkins); BRD 66,000 U/kg IM/SC once daily with a 20-day slaughter withdrawal (Hjerpe). Label doses are lower (≈6,600 U/kg) and label withdrawals apply only to them — higher extra-label doses need FARAD-extended meat and milk withdrawals. Aspirate before injecting; never IV. Calves, clostridial abomasitis: 10,000–20,000 U/kg PO q12–24h for 1–4 days.

### Rabbits

*Procaine Penicillin G doses for rabbits*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Venereal spirochetosis (Treponema) | 20000–84000 mg/kg | SC | q24h | 5–7 days |

- Venereal spirochetosis (Treponema): UNITS/kg. Plumb’s p.945 (Ivey & Morrisey 2000): 20,000–84,000 U/kg SC or IM q24h. Parenteral only — oral penicillins cause fatal dysbiosis in rabbits.

### Ferrets

*Procaine Penicillin G doses for ferrets*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Susceptible infection | 20000–40000 mg/kg | IM | q12–24h | — |

- Susceptible infection: UNITS/kg. Plumb’s p.945 (Williams 2000): procaine penicillin G 20,000–40,000 units/kg IM once or twice daily.

## Contraindications

INTRAVASCULAR / IV injection (fatal procaine reaction — always aspirate; IM only). Penicillin/procaine (local anaesthetic ester) hypersensitivity. NEVER orally in rabbits/guinea pigs/hamsters (fatal enterotoxaemia). Adult horses/hindgut fermenters risk antibiotic-associated colitis. Observe food-animal withdrawal.

## Species-specific warnings

> **Caution:** Horses: Aspirate carefully — procaine reactions are a well-known equine hazard; also watch for antibiotic-associated colitis and drug-test positives.

> **Caution:** Rabbits: Never give penicillins orally to rabbits/small mammals — fatal enterotoxaemia.

## Adverse effects

- PROCAINE reaction if given IV/intravascular (excitement, ataxia, collapse, death)
- Hypersensitivity/anaphylaxis (penicillin)
- Injection-site swelling/pain, sterile abscess
- Antibiotic-associated diarrhoea/colitis (horses); positive drug tests (procaine)

## Drug interactions

- Aminoglycosides (dihydrostreptomycin): synergy/broader cover (fortified products) — but inactivate each other if mixed and stored
- Bacteriostatic antibiotics: possible antagonism
- Probenecid: prolongs penicillin levels
- Procaine: local-anaesthetic interactions; positive competition drug tests

## Pregnancy and lactation

Penicillins are among the safest antibiotics in pregnancy/lactation; widely used in food animals (observe withdrawal).

## Monitoring

- Aspirate the syringe before injecting (avoid intravascular procaine reaction) — the key safety step
- Hypersensitivity at first dose; injection-site reactions
- Clinical response; food-animal withdrawal compliance
- Procaine positive drug tests in competition horses

## Toxicity and overdose

Two distinct hazards: (1) penicillin hypersensitivity/anaphylaxis, and (2) the PROCAINE reaction from inadvertent intravascular injection — acute CNS excitement, ataxia, tremor, collapse, and occasionally death (procaine toxicity, not penicillin). Very wide margin otherwise. Oral penicillins are fatal to rabbits/small hindgut fermenters.

Management: For a procaine reaction: this is usually self-limiting over minutes — keep the animal calm/safe, provide supportive care; severe cases need cardiovascular/respiratory support. For anaphylaxis: epinephrine 0.01 mg/kg IM, antihistamine, corticosteroid, oxygen, IV fluids. No specific antidote — ALWAYS aspirate before injecting to prevent the reaction.

## Clinical pearls

- The everyday once-daily depot penicillin for cattle/horses/pigs — procaine slows release for ~24 h of cover (unlike crystalline penicillin G, which needs frequent dosing)
- ALWAYS aspirate before IM injection — accidental IV delivery causes an acute, sometimes fatal PROCAINE reaction (a distinct hazard from penicillin allergy)
- Shake the suspension and keep it refrigerated; Indian products are often fortified with dihydrostreptomycin for broader cover
- Remember procaine can trigger positive drug tests in performance horses; observe food-animal withdrawal

## Mechanism of action

The penicillin-G moiety is a beta-lactam that binds penicillin-binding proteins, inhibiting peptidoglycan cross-linking and bacterial cell-wall synthesis — bactericidal, time-dependent. The procaine salt is poorly soluble, forming a depot at the IM site from which penicillin is released slowly over ~24 h (sustained therapeutic levels from once-daily dosing). Free procaine (a local anaesthetic) released intravascularly is responsible for the acute CNS "procaine reaction."

## Formulations and products

- Injectable suspension 300,000 IU/mL
- Fortified procaine penicillin (with dihydrostreptomycin)
- Procaine Penicillin (± dihydrostreptomycin) (Various (India)) — 300,000 IU/mL suspension (fortified forms), IM depot injection
- Strepto-Penicillin 2.5 g (Assure Biotech, Jagadhri (HR)) — Procaine penicillin G 1.5 MIU + Penicillin G sodium 0.5 MIU + Streptomycin base 2.5 g, Dry powder vial for suspension
- Strepto-Penicillin 5 g (Assure Biotech, Jagadhri (HR)) — Procaine penicillin G 3 MIU + Penicillin G sodium 3 MIU + Streptomycin base 5 g, Dry powder vial for suspension

## Storage

Suspension: REFRIGERATE (2–8 °C) per label; shake well before use (settles). Do not freeze. Protect from light.

## 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.

## Other antibiotics

- [Penicillin G](https://vetmasterji.com/drugs/penicillin-g)
- [Pirlimycin](https://vetmasterji.com/drugs/pirlimycin)
- [Polymyxin B](https://vetmasterji.com/drugs/polymyxin-b)
- [Pradofloxacin](https://vetmasterji.com/drugs/pradofloxacin)
- [Rifampin](https://vetmasterji.com/drugs/rifampin)
- [Rifaximin](https://vetmasterji.com/drugs/rifaximin)
- [Silver Sulfadiazine](https://vetmasterji.com/drugs/silver-sulfadiazine)
- [Spectinomycin](https://vetmasterji.com/drugs/spectinomycin)

## Frequently asked questions

### What is the dose of Procaine Penicillin G for dogs?

Reference doses for Procaine Penicillin G in dogs: 20000–40000 mg/kg IM q12–24h (Susceptible infection). Confirm against the label and the patient before use.

### What is the dose of Procaine Penicillin G for cats?

Reference doses for Procaine Penicillin G in cats: 20000–40000 mg/kg IM q8–12h (Soft-tissue / orthopaedic infection). Confirm against the label and the patient before use.

### What is the dose of Procaine Penicillin G for cattle?

Reference doses for Procaine Penicillin G in cattle: 10000–40000 mg/kg IM q12–24h (Susceptible Gram-positive infection). Confirm against the label and the patient before use.

### What is the withdrawal period for Procaine Penicillin G?

Cattle, IM (Susceptible Gram-positive infection): Withdrawal NOT established — treat as extra-label; Goats, IM (Susceptible infection (extra-label)): Withdrawal NOT established — treat as extra-label; Sheep, IM (Foot rot / clostridial disease): Withdrawal NOT established — treat as extra-label; Pigs, IM (Erysipelas / susceptible infection): Withdrawal NOT established — treat as extra-label. Follow the product label and national regulations where they differ.

### When should Procaine Penicillin G not be used?

INTRAVASCULAR / IV injection (fatal procaine reaction — always aspirate; IM only). Penicillin/procaine (local anaesthetic ester) hypersensitivity. NEVER orally in rabbits/guinea pigs/hamsters (fatal enterotoxaemia). Adult horses/hindgut fermenters risk antibiotic-associated colitis. Observe food-animal withdrawal.

### What are the side effects of Procaine Penicillin G in animals?

PROCAINE reaction if given IV/intravascular (excitement, ataxia, collapse, death); Hypersensitivity/anaphylaxis (penicillin); Injection-site swelling/pain, sterile abscess; Antibiotic-associated diarrhoea/colitis (horses); positive drug tests (procaine).

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- 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.