Cefadroxil — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	PO	22 mg/kg	q12h	Duration: 5-7 days for acute infections; 10-14 days for chronic or deep infections Notes: For pyoderma, continue treatment for 2-3 days beyond clinical resolution.
Cat	PO	22 mg/kg	q12h	Duration: 5-7 days Notes: Use cautiously in cats with renal impairment; adjust dose if needed.
Horse	PO	25 mg/kg	q12h	Duration: 5-10 days Notes: Oral absorption may be variable; consider alternative if severe infection.
Cattle	PO	10-15 mg/kg	q12h	Duration: 3-5 days Notes: Not approved for food animals in many countries; extra-label use requires veterinary oversight and extended withdrawal times.
Sheep/Goats	PO	10-15 mg/kg	q12h	Duration: 3-5 days Notes: Extra-label use; observe withdrawal times.
Rabbit	PO	15-25 mg/kg	q12h	Duration: 5-7 days Notes: May cause GI upset; monitor for diarrhea.
Birds	PO	50-100 mg/kg	q12h	Duration: 5-7 days Notes: Dose based on limited studies; adjust based on species and severity.

Clinical Indications & Species Uses

General Indications

Treatment of infections caused by susceptible gram-positive and gram-negative bacteria

Dog (Canine)

Treatment of skin and soft tissue infections (pyoderma, wounds, abscesses)
Urinary tract infections (cystitis, pyelonephritis)
Respiratory tract infections (pneumonia, bronchitis)
Bone and joint infections (osteomyelitis, septic arthritis)

Cat (Feline)

Skin and soft tissue infections
Urinary tract infections
Respiratory tract infections

Horse (Equine)

Respiratory tract infections (e.g., strangles, pneumonia)
Skin and soft tissue infections
Urinary tract infections

Cattle (Bovine)

Respiratory tract infections (e.g., bovine respiratory disease complex)
Metritis
Foot rot
Mastitis (when caused by susceptible organisms)

Small Ruminants (Sheep / Goat)

Respiratory tract infections
Skin infections
Urinary tract infections

Rabbit & Small Mammals

Respiratory tract infections (e.g., pasteurellosis)
Skin infections
Urinary tract infections

Avian & Poultry

Respiratory tract infections
Skin and soft tissue infections
Urinary tract infections

Exotic & Other Species

Reptiles: skin and respiratory infections
Small mammals (ferrets, guinea pigs): respiratory and skin infections

Pharmacology & Mechanism of Action

Drug Class: Cephalosporin antibiotic | Pharmacological Group: First-generation cephalosporin

Mechanism of Action: Cefadroxil is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs) and interfering with peptidoglycan cross-linking. This leads to cell wall weakening, osmotic instability, and ultimately bacterial lysis. It is bactericidal against susceptible organisms.

Pharmacodynamics: Cefadroxil has a broad spectrum of activity against gram-positive bacteria (e.g., Staphylococcus spp., Streptococcus spp.) and some gram-negative bacteria (e.g., Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis). It is resistant to many beta-lactamases produced by gram-positive bacteria but is less stable against those from gram-negative organisms. Its activity is time-dependent, with efficacy correlated with the time the drug concentration remains above the minimum inhibitory concentration (MIC).

⚡ Pharmacokinetics Summary

Absorption: Cefadroxil is well absorbed after oral administration in most species. In dogs, bioavailability is approximately 100% after oral dosing. Absorption is not significantly affected by food, but administration with food may delay peak concentrations.

Distribution: Cefadroxil distributes widely into body tissues and fluids, including skin, soft tissues, respiratory tract, urinary tract, and bone. It penetrates well into interstitial fluid and is distributed into the prostate and synovial fluid. It crosses the blood-brain barrier poorly unless the meninges are inflamed. Protein binding is low (approximately 20% in dogs).

Metabolism: Cefadroxil undergoes minimal metabolism in the body. The majority of the drug is excreted unchanged.

Excretion: Cefadroxil is primarily excreted by the kidneys via glomerular filtration and tubular secretion. In dogs, approximately 90% of the dose is recovered in urine within 24 hours. Biliary excretion is minimal.

Half-Life: Dog: 2-3 hours; Cat: 2-4 hours; Horse: 1-2 hours; Cattle: 2-3 hours; Sheep/Goats: 2-3 hours; Rabbits: 1-2 hours; Birds: 1-2 hours.

Bioavailability: Oral: ~100% in dogs; ~90% in cats; ~80% in horses; ~70-90% in ruminants.

Protein Binding: Approximately 20% in dogs; 15-20% in other species.

Available Formulations & Strengths

Oral Tablet 250 mg, 500 mg, 1 g (PO)

Oral Capsule 500 mg (PO)

Oral Suspension 125 mg/5 mL, 250 mg/5 mL, 500 mg/5 mL (PO)

Contraindications & Clinical Warnings

Contraindications:

Known hypersensitivity to cephalosporins or beta-lactam antibiotics
History of anaphylactic reactions to penicillins (cross-reactivity risk)
Use in small herbivores (e.g., rabbits, guinea pigs) with caution due to risk of GI dysbiosis

Warnings & Clinical Precautions:

Use with caution in animals with renal impairment; dose adjustment may be necessary.
Prolonged use may result in overgrowth of non-susceptible organisms (e.g., Clostridium difficile).
In food animals, observe withdrawal times and comply with extra-label drug use regulations.
May cause gastrointestinal upset; administer with food to reduce nausea.
Use in pregnant or lactating animals only if clearly needed; safety not fully established.

Adverse Effects & Reactions

Common:

Gastrointestinal upset (vomiting, diarrhea, anorexia)
Hypersensitivity reactions (skin rash, urticaria)

Serious / Severe:

Anaphylaxis
Acute renal failure (rare)
Clostridium difficile-associated diarrhea
Blood dyscrasias (neutropenia, thrombocytopenia)

Rare:

Hepatotoxicity
Neurological signs (seizures) at high doses
Superinfections (candidiasis)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Probenecid	Decreases renal tubular secretion of cefadroxil, increasing its plasma concentration and half-life.	Moderate
Aminoglycosides (e.g., gentamicin)	Additive nephrotoxicity; monitor renal function.	High
Loop diuretics (e.g., furosemide)	May increase nephrotoxicity of cephalosporins.	Moderate
Bacteriostatic antibiotics (e.g., tetracyclines, macrolides)	Potential antagonism of bactericidal activity; avoid concurrent use.	Moderate

Overdose & Toxicity Management

Signs of Toxicity:

Gastrointestinal signs (vomiting, diarrhea)
Neurological signs (seizures, tremors) at very high doses
Acute renal failure (rare)

Emergency Treatment Protocol: Induce emesis if recent ingestion and animal is stable. Administer activated charcoal to reduce absorption. Provide supportive care including IV fluids to maintain hydration and renal perfusion. Monitor renal function and neurological status. Seizures may be controlled with diazepam or barbiturates. There is no specific antidote.

Food Animal Withdrawal Times

🥩 Meat: 4 days🥛 Milk: 3 days

Withdrawal times are not established for cefadroxil in food animals in many countries; extra-label use requires extended withdrawal periods (e.g., meat 4 days, milk 3 days as a general guideline). Consult regulatory authorities for specific requirements.

Storage, Handling & Regulatory Information

Storage Temperature: Store at room temperature (20-25°C) in a tight container.

Handling & Special Conditions: Protect from moisture. Reconstituted oral suspension should be refrigerated and used within 14 days.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; human-approved product may be used extra-label.

Extra-Label (Off-Label) Use: In the US, cefadroxil is not approved for veterinary species; use in animals is extra-label under AMDUCA. For food animals, a valid veterinarian-client-patient relationship is required, and withdrawal times must be extended. In some countries, cefadroxil is approved for dogs and cats.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Cefadroxil is a first-generation cephalosporin with good activity against gram-positive cocci and some gram-negative organisms. It is commonly used in small animal practice for skin, urinary, and respiratory infections. Its excellent oral bioavailability and low protein binding make it a convenient choice for outpatient therapy. However, its spectrum is limited compared to newer cephalosporins, and resistance among gram-negative bacteria is increasing. In horses and ruminants, oral absorption may be variable, and parenteral alternatives may be preferred for severe infections. Always perform culture and sensitivity testing when possible. Monitor renal function in animals with pre-existing kidney disease or when using concurrently with nephrotoxic drugs.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)