Calculate cephalexin (Keflex) dosage for cats by weight and infection type. Covers oral suspension and capsule forms with feline safety guidelines.
Cephalexin is a first-generation cephalosporin antibiotic commonly prescribed for cats to treat bacterial skin infections, urinary tract infections, wound infections, and bone infections. While not FDA-approved specifically for cats, it is widely used off-label by veterinarians and has a well-established safety profile in feline patients.
The standard dosage for cats is 10-15 mg/lb (22-33 mg/kg) given orally every 8-12 hours. Treatment duration typically ranges from 7-14 days for skin infections to 4-6 weeks for deep or bone infections. This calculator helps determine the correct dose based on your cat's weight and the available formulation.
Cephalexin is available as capsules (250 mg, 500 mg) and oral suspension (125 mg/5 mL, 250 mg/5 mL). For cats, the oral suspension is often preferred due to easier dose adjustment for their small body weight. Always complete the full course of antibiotics as prescribed — stopping early promotes antibiotic resistance. If symptoms fail to improve within a few days, prompt veterinary reassessment can prevent progression and support safer antibiotic selection.
For best results, combine calculator output with direct observation and periodic check-ins with a veterinarian or qualified advisor. Small adjustments made early usually improve comfort, safety, and long-term outcomes more than large corrective changes made later.
Accurate antibiotic dosing is essential for treatment success and preventing resistance. Underdosing leads to treatment failure, while overdosing increases side effects. This calculator ensures precise measurement, especially important for small cats where dose margins are narrow. This cephalexin for cats dosage calculator helps you compare outcomes quickly and reduce avoidable mistakes when making day-to-day care decisions. Use the estimate as a planning baseline and confirm final decisions with a qualified professional when risk is high.
Dose (mg) = Weight (lbs) × Dose Rate (mg/lb). Standard rate: 10-15 mg/lb (22-33 mg/kg). Oral suspension: Dose Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). Capsules: round to nearest available size. Daily total = Dose × Frequency (2 or 3 times).
Result: 125 mg per dose (5 mL), 250 mg daily for 14 days
A 10-pound cat at 12.5 mg/lb needs 125 mg per dose. Using 125 mg/5 mL suspension, administer 5 mL twice daily. For skin infections, continue for 14 days or as directed by your veterinarian.
Cephalexin is effective against many gram-positive organisms including Staphylococcus, Streptococcus, and some gram-negative bacteria like E. coli and Proteus. It works by inhibiting bacterial cell wall synthesis, making it bactericidal. It's often the first-choice antibiotic for feline skin infections and abscesses, which are extremely common in outdoor or multi-cat households.
Pilling a cat is challenging for many owners. The oral suspension form is generally easier: draw the correct volume into a small syringe, gently hold the cat's head, and slowly squirt the liquid into the cheek pouch. Mixing with a teaspoon of tuna juice or chicken broth can improve acceptance. For capsule forms, pill pockets or compounded flavored preparations may be available through your veterinarian.
Observe your cat's response to treatment over the first 48-72 hours. Improvement in appetite, activity, and reduction of discharge or swelling are positive signs. If no improvement is seen after 72 hours, a culture and sensitivity test may be needed to identify resistant bacteria. Follow-up appointments ensure the infection has fully resolved.
Cephalexin is considered safe for most cats when prescribed by a veterinarian. Side effects are typically mild — occasional vomiting, diarrhea, or decreased appetite. Cats with known penicillin allergies may have cross-reactivity (5-10% risk).
Common uses include skin and soft tissue infections (abscesses, wound infections), urinary tract infections, bone infections (osteomyelitis), and respiratory infections. It's effective against many gram-positive bacteria and some gram-negatives.
The active ingredient is identical, but you should only give it under veterinary guidance. Human capsules may need to be opened and divided for accurate cat dosing. Never self-prescribe antibiotics — inappropriate use promotes resistance.
Duration depends on the infection: 7-14 days for simple skin infections, 14-21 days for UTIs, and 4-6 weeks for bone or deep infections. Always complete the full prescribed course even if symptoms improve.
Give cephalexin with a small amount of food to reduce stomach upset. If vomiting persists, contact your vet — they may adjust the dose, switch to a different formulation, or prescribe an anti-nausea medication.
Cephalexin is generally safe for kittens over 6 weeks old, but dosing must be precise. Kittens under 6 weeks or severely debilitated should only receive antibiotics under close veterinary supervision.