Ceftriaxone

Ceftriaxone is a parenteral third-generation cephalosporin used extra-label for selected serious bacterial infections in veterinary patients. Its spectrum includes many susceptible gram-negative organisms and some gram-positive pathogens. Tissue distribution, including penetration into inflamed meninges, supports selected deep-infection applications. Veterinary experience and exposure differ substantially among species.

Group

Third-generation cephalosporin antibacterial

Mechanism of Action

Ceftriaxone binds bacterial penicillin-binding proteins and inhibits transpeptidation during peptidoglycan synthesis. Failure of normal cell-wall cross-linking weakens growing bacteria and leads to lysis. Activity is bactericidal and depends on adequate exposure relative to organism susceptibility. Its resistance to some beta-lactamases broadens activity, although other beta-lactamases and altered targets can confer resistance.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Susceptible bacterial infection	50 mg/kg	IM, SC	Every 12–24 h	Pharmacokinetic proposal from healthy dogs; select interval using organism susceptibility and infection site. SC is extralabel.
Meningitis or borreliosis	15–50 mg/kg	IV, IM	Every 12 h	Up to 14 days; Listed course 4–14 days. The cited 1 g single-dose ceiling is a human limit, not an established canine maximum.
Perioperative antibacterial prophylaxis	25 mg/kg	IV, IM	Once
Skin or genitourinary infection	25 mg/kg	IM	Every 24 h	Up to 14 days; Listed course 7–14 days.
Infectious endocarditis	20 mg/kg	IV	Every 12 h	When resistance or other contraindications preclude fluoroquinolones and aminoglycosides.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Systemic bacterial infection	25–50 mg/kg	IV, IM, IO	Every 12 h

Horses

Use / stage	Dose	Route	Schedule	Instructions
Susceptible bacterial infection	25–50 mg/kg	IV, IM	Every 12 h
Alternative susceptible infection regimen	20 mg/kg	IV	Every 12 h

Indications

Treatment of selected ceftriaxone-susceptible systemic infections, including sepsis, in veterinary patients.
Treatment of selected susceptible bacterial pneumonia, urinary infection or deep soft-tissue infection.
Specialist treatment of susceptible bacterial meningitis or other central nervous system infection, with species- and organism-specific support.

Contraindications

Serious cephalosporin hypersensitivity

Interactions

Calcium-containing IV solutions can precipitate with ceftriaxone; avoid concurrent admixture.
Do not mix with other medicines without established compatibility.
Aminoglycosides and other nephrotoxic medicines may increase renal adverse effects.
Calcium precipitation risk is particularly important in neonates; exact separation and line requirements are product dependent.

Adverse effects

Injection-site discomfort
Gastrointestinal disturbance
Hypersensitivity
Biliary sludge with high exposure
Possible cytopenias and increased hepatic or renal laboratory indices

Toxicity

Overexposure may increase beta-lactam neurologic adverse effects; discontinue and provide supportive care if toxicity develops.

Preparations

Preparation	Form	Strength	Route
Ceftriaxone injection 1 g vial Strength expressed as ceftriaxone equivalent, supplied as sodium salt. Final concentration depends on the selected reconstitution.	Injection	1000 mg / vial	IV, IM
Ceftriaxone powder 250 mg vial Strength expressed as ceftriaxone base equivalent from sodium salt; verify exact final concentration after reconstitution.	Injection	250 mg / vial	IV, IM
Ceftriaxone powder 500 mg vial Strength expressed as ceftriaxone base equivalent from sodium salt; verify exact final concentration after reconstitution.	Injection	500 mg / vial	IV, IM
Ceftriaxone powder 2000 mg vial Strength expressed as ceftriaxone base equivalent from sodium salt; verify exact final concentration after reconstitution.	Injection	2000 mg / vial	IV, IM

Monitoring and Administration

Obtain culture and susceptibility results for serious infections.

The dog regimens are pharmacokinetically proposed schedules, rather than a proven regimen for every infection.

Assess renal and hepatobiliary function during prolonged therapy. Use a product-specific reconstitution instruction; do not derive final volume from added diluent alone.

Administer IV ceftriaxone over at least 30 minutes. Consider adjustment in severe renal dysfunction, particularly with simultaneous hepatic impairment; assess icterus or biliary disease before treatment.

For longer courses, follow CBC, renal indices, urinalysis and liver enzymes. Copper-reduction urine glucose tests can be falsely positive; high concentrations may interfere with some manual creatinine methods.

Use product-specific storage periods: described approximately 100 mg/mL saline/D5W solutions were stable for 3 days at room temperature or 10 days refrigerated; approximately 250 mg/mL solutions for 24 hours or 3 days, respectively. These periods are not interchangeable across concentrations or formulations.