Cefazolin
Cefazolin is an injectable first-generation cephalosporin used when parenteral antibacterial treatment is required. Its useful activity against susceptible staphylococci and streptococci makes it a common agent for surgical prophylaxis and for selected skin, soft-tissue, bone and joint infections. It also covers a limited selection of gram-negative organisms.
Group
First-generation cephalosporin
Mechanism of Action
Cefazolin binds bacterial penicillin-binding proteins and inhibits the transpeptidase reactions that cross-link peptidoglycan. This produces a mechanically defective cell wall and bactericidal activity against actively growing susceptible bacteria. Its activity is time dependent, with antibacterial effect related to the duration that unbound concentrations exceed the minimum inhibitory concentration. Its spectrum principally favors susceptible gram-positive cocci.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bacterial infections | 25 mg/kg | IV, IM | Every 6 h | |
| Antibacterial infusion — Loading | 1.3 mg/kg | IV | Once | |
| Antibacterial infusion — Maintenance | 1.2 mg/kg/hour | IV | Continuous | |
| Perisurgical prophylaxis | 22 mg/kg | IV | Every 2 h | Repeat only during surgery as indicated by procedure duration. |
| Gram-positive infection | 10 mg/kg | IV, IM | Every 8 h | |
| Susceptible bacterial infection | 10–30 mg/kg | IV | Every 8 h | |
| Gram-negative infection | 30 mg/kg | IM, SC | ||
| Sepsis | 20–25 mg/kg | IV | Every 4–8 h | |
| Orthopedic surgical prophylaxis | 20 mg/kg | IV | Every 1.5 h | Begin at induction and repeat every 90 minutes until wound closure. |
| Soft-tissue surgical prophylaxis | Reference only | IV | 20 mg/kg IV at surgery, followed by 20 mg/kg SC six hours later. This is a staged route-changing regimen, not indefinite six-hour dosing. | |
| Neonatal bacterial infection | 10–30 mg/kg | IV, IO | Every 8 h | Neonates only. |
| Surgical prophylaxis | 8 mg/kg | IV | Every 1 h | Alternative perioperative regimen; do not combine with the 20–22 mg/kg schedule. |
| Surgical prophylaxis | 20–22 mg/kg | IV | Every 2 h | Immediately before and during surgery. |
| Systemic infection | 5–25 mg/kg | IM, IV | Every 6–8 h | |
| Orthopedic infection | 22 mg/kg | IV, IM, SC | Every 6–8 h | Up to 7 days |
| Sepsis or bacteremia | 15–25 mg/kg | IV, IM, SC | Every 4–8 h | Up to 7 days |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bacterial infections | 25 mg/kg | IV, IM | Every 6 h | |
| Antibacterial infusion — Loading | 1.3 mg/kg | IV | Once | |
| Antibacterial infusion — Maintenance | 1.2 mg/kg/hour | IV | Continuous | |
| Perisurgical prophylaxis | 22 mg/kg | IV | Every 2 h | Repeat only during surgery as indicated by procedure duration. |
| Gram-positive infection | 10 mg/kg | IV, IM | Every 8 h | |
| Susceptible bacterial infection | 10–30 mg/kg | IV | Every 8 h | |
| Gram-negative infection | 30 mg/kg | IM, SC | ||
| Sepsis | 20–25 mg/kg | IV | Every 4–8 h | |
| Orthopedic surgical prophylaxis | 20 mg/kg | IV | Every 1.5 h | Begin at induction and repeat every 90 minutes until wound closure. |
| Soft-tissue surgical prophylaxis | Reference only | IV | 20 mg/kg IV at surgery, followed by 20 mg/kg SC six hours later. This is a staged route-changing regimen, not indefinite six-hour dosing. | |
| Neonatal bacterial infection | 10–30 mg/kg | IV, IO | Every 8 h | Neonates only. |
| Systemic infection | 33 mg/kg | IV, IM | Every 8–12 h | |
| Bacterial infections | 20–25 mg/kg | IM, IV | Every 8 h |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bacterial infections | 25 mg/kg | IM, IV | Every 6 h | |
| Bacterial infections | 25 mg/kg | IV, IM | Every 6–8 h | |
| Foal bacterial infection | 20 mg/kg | IV | Every 8–12 h | Foals only. |
| Neonatal foal infection | 15–20 mg/kg | IV | Every 8 h | Neonatal foals only. |
Chelonians
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Bacterial infections | 22 mg/kg | IM | Every 24 h |
Indications
- Perioperative prevention of surgical-site infection in dogs, cats and horses undergoing procedures for which antibacterial prophylaxis is indicated.
- Parenteral treatment of susceptible skin and soft-tissue infections in dogs and cats.
- Treatment of susceptible osteomyelitis and septic arthritis in veterinary patients.
- Treatment of selected systemic infections, including bacteremia or sepsis, caused by susceptible organisms.
Contraindications
- Cephalosporin hypersensitivity; assess prior severe beta-lactam allergy.
Interactions
- Avoid mixing with other drugs in the same vial or syringe unless compatibility is established.
Adverse effects
- Hypersensitivity
- Gastrointestinal upset
- Injection-site reactions with parenteral products
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Cefazolin 500 mg vial Strength is per vial; no final mL concentration is implied. | Injection | 500 mg / vial | IV, IM |
| Cefazolin 1000 mg vial Strength is per vial; no final mL concentration is implied. | Injection | 1000 mg / vial | IV, IM |
Monitoring and Administration
Choose treatment using organism identity, infection site and susceptibility testing. Reassess clinical response and renal function where impaired clearance may increase exposure.
Food-animal authorization and withdrawal periods depend on the exact formulation, species, regimen and jurisdiction; do not transfer foreign approvals or residue intervals to another product.
The source contains inconsistent infusion strength wording; only unambiguous vial masses are encoded. Reported reconstituted stability is 24 hours at room temperature, 14 days refrigerated or 3 months frozen, dependent on the specific preparation.
Give IV doses over at least 3–5 minutes and use a large muscle mass for IM delivery. Renal impairment may require dose adjustment.
Reconstituted stability differs by manufacturer and container: the supplement describes 24 hours at room temperature, 96 hours refrigerated or 12 weeks frozen in the original container. Do not substitute the longer refrigerated period reported for a different preparation.