DogSource: Rebuello/Albarellos 2002
50 mg/kg IM · once to twice daily
Antibiotic Therapy
Ceftriaxone
Third-generation (injectable) cephalosporin · bactericidal (cell-wall synthesis inhibitor)
Species: Dogs & Cats7 dose protocols4 dosage forms
This page is a calculation and educational reference for veterinarians and veterinary students. It does not replace examination, culture and susceptibility testing, clinical judgment, or the attending veterinarian's final decision.
Drug overview
Third-generation (injectable) cephalosporin · bactericidal (cell-wall synthesis inhibitor)
Brand names: Rocephin®
Dose reference only—not an empiric regimen: 25 mg/kg parenteral · every 12–24 hSource: Plumb's (general)
Spectrum of activity
A third-generation, bactericidal cephalosporin with broad Gram-negative coverage (Enterobacteriaceae such as E. coli and Klebsiella, Pasteurella, Haemophilus, Neisseria) and good penetration into the central nervous system. It is active against streptococci and methicillin-susceptible staph, and also covers spirochetes (Borrelia of Lyme disease, Leptospira). But it has no activity against Pseudomonas, Enterococcus and Listeria (intrinsic cephalosporin resistance), methicillin-resistant staph (MRSA), or intracellular/cell-wall-free bacteria (Mycoplasma, Rickettsia). Its anaerobic coverage is weak; for anaerobic infections it is usually combined with metronidazole.
Veterinary uses and doses
General / systemic infection
DogSource: Trepanier 1999
15–50 mg/kg parenteral · once daily
CatSource: Greene 1998
Cat: 25–50 mg/kg IV, IM or IO · every 12 h
Meningitis / borreliosis (Lyme)
DogSource: Greene 1998
15–50 mg/kg IV or IM · every 12 h · 4–14 days
Clinical note: The usual single-dose maximum (based on human data) is about 1 gram.
Skin & genitourinary
DogSource: Greene 1998
25 mg/kg IM · once daily · 7–14 days
Infective endocarditis
DogSource: DeFrancesco 2000
20 mg/kg IV · every 12 h
Clinical note: In endocarditis, used as an alternative when fluoroquinolones and aminoglycosides are resisted or contraindicated.
Surgical prophylaxis
DogSource: Greene 1998
25 mg/kg IV or IM · single dose (pre/intra-op)
Dosage forms
- Vial 1000 mg (1 g)
- Vial 500 mg
- Vial 250 mg
- Vial 2000 mg (2 g)
Safety and clinical notes
- ⚠️ Reserve-drug quick reference: the general dose is a calculation reference, not an empiric treatment regimen. Use ceftriaxone only for a defined indication and, whenever feasible, a susceptible isolate documented by culture and susceptibility testing when narrower first-line options are unsuitable.
- Injectable only (not absorbed orally): IV or IM. Give IV as an infusion over at least 30 minutes in compatible fluids (normal saline, D5W, or dextrose-saline); IM injection is painful.
- ⚠️ Do not reconstitute or further dilute ceftriaxone with calcium-containing fluids (such as Ringer's, lactated Ringer's, or Hartmann's), and do not mix or administer them simultaneously through the same IV line. If sequential administration is required in a non-neonatal patient, thoroughly flush the line with a compatible fluid between infusions; avoid ceftriaxone in neonates receiving IV calcium.
- Contraindicated in cephalosporin allergy; up to 16% of penicillin-allergic patients may cross-react.
- Dose adjustment is needed in severe renal impairment or concurrent hepatic dysfunction; avoid in jaundice (icterus).
- Adverse effects: hematologic reactions (eosinophilia, thrombocytosis or thrombocytopenia, leukopenia, neutropenia), diarrhea, mild azotemia, and IM injection-site pain.
- Reconstitute the vial powder with sterile water, normal saline or D5W (choose the diluent volume in this app); at about 100 mg/mL it is stable refrigerated for up to 10 days. Common vials: 250, 500, 1000 and 2000 mg.
Cited sources
- Plumb's (general)
- Rebuello/Albarellos 2002
- Trepanier 1999
- Greene 1998
- DeFrancesco 2000
Calculate a weight-based dose
Drug-data last updated: