Convenia (Cefovecin) Intramuscular Administration in Dogs and Cats
Direct Answer
Convenia should be administered as a single subcutaneous injection at 8 mg/kg (3.6 mg/lb) body weight, NOT intramuscularly, as this is the FDA-approved route that provides 14 days of therapeutic coverage in dogs and cats. While the evidence documents IM administration in research settings, the standard of care is subcutaneous injection.
FDA-Approved Administration Route and Dosing
Subcutaneous injection is the labeled route of administration for Convenia in dogs and cats. 1, 2
- Standard dose: 8 mg/kg body weight as a single injection 3, 2
- Duration of action: Provides therapeutic plasma concentrations for 14 days in both species 1, 4
- Injection site: Administered subcutaneously, typically between the shoulder blades or in the scruff region 1
Pharmacokinetic Basis for Subcutaneous Administration
The extended duration of action in dogs and cats is achieved through:
- Exceptionally high plasma protein binding (>98-99%) in carnivores, which prolongs elimination half-life 4, 2
- Elimination half-life: 133 hours in dogs and 166 hours in cats following subcutaneous administration 3
- Active renal tubular reabsorption in dogs and cats maintains therapeutic concentrations 3
- Peak plasma concentrations: Approximately 85 µg/mL in felids after IM injection, though SC is the standard route 2
Evidence for Intramuscular Administration
While IM administration has been studied in research settings, it is not the labeled route:
- Cheetah study: 8 mg/kg IM produced peak concentrations of 84.75 µg/mL with elimination half-life of 144.1 hours (6 days) 2
- Nonhuman primate studies: IM administration at 8 mg/kg resulted in much shorter half-lives (4.95-9.17 hours), demonstrating species-specific pharmacokinetics 3
- Plasma concentrations >7 µg/mL were maintained for 15 days in cheetahs after IM injection 2
Common Indications and Appropriate Use
Cefovecin is frequently used for:
In cats:
In dogs:
Critical Prescribing Considerations
Culture and susceptibility testing is rarely performed but strongly recommended:
- Only 0.3% of cefovecin prescriptions in first-opinion practice were preceded by culture and susceptibility testing 1
- As a third-generation cephalosporin, cefovecin is a critically important antimicrobial that should only be used after culture confirmation or when first-line agents have failed 1
- Empirical use without culture contributes to antimicrobial resistance 1
Contraindications and Precautions
β-lactam allergy:
- Absolute contraindication in animals with documented hypersensitivity to cephalosporins or penicillins 1
Hepatic or renal disease:
- No specific dose adjustments are provided in the veterinary literature for hepatic impairment 1, 4
- Renal clearance approximates plasma clearance in species without active tubular reabsorption 3
- Use with caution in animals with significant renal impairment, as accumulation may occur 3
Species-Specific Pharmacokinetic Failures
Cefovecin does NOT provide extended duration in:
- Birds: Half-life 0.9 hours in hens 5
- Reptiles: Half-life 3.9 hours in green iguanas 5
- Nonhuman primates: Half-life 4.95-9.17 hours 3
These species lack the active renal reabsorption mechanism present in dogs and cats 3, 5
Common Pitfalls to Avoid
- Using cefovecin without culture and susceptibility testing when first-line antimicrobials are appropriate 1
- Assuming IM and SC routes are interchangeable without pharmacokinetic data supporting equivalent bioavailability
- Extrapolating the 14-day duration to non-carnivore species, where elimination is dramatically faster 3, 5
- Prescribing for surgical prophylaxis when shorter-acting, less critically important antimicrobials are more appropriate 1