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PetDosageChart

Keflex (Cephalexin) Dosage for Dogs

Antibiotic (Cephalosporin) ⏱ Onset: 1-2 hours ⏳ Duration: 8-12 hours

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. This information is sourced from veterinary drug references including Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

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Keflex Dosage Chart for Dogs by Weight

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Weight Low Dose Standard Dose Max Dose Frequency
5 lbs (2.3 kg) 23mg 50.5mg 69mg every 8-12 hours
10 lbs (4.5 kg) 45mg 99mg 135mg every 8-12 hours
15 lbs (6.8 kg) 68mg 149.5mg 204mg (250mg tablet) every 8-12 hours
20 lbs (9.1 kg) 91mg 200mg (250mg tablet) 273mg (250mg tablet) every 8-12 hours
25 lbs (11.3 kg) 113mg 248.5mg (250mg tablet) 339mg every 8-12 hours
30 lbs (13.6 kg) 136mg 299mg (250mg tablet) 408mg every 8-12 hours
40 lbs (18.1 kg) 181mg 398mg 543mg (2 × 250mg) every 8-12 hours
50 lbs (22.7 kg) 227mg (250mg tablet) 499.5mg (2 × 250mg) 681mg every 8-12 hours
60 lbs (27.2 kg) 272mg (250mg tablet) 598.5mg 816mg every 8-12 hours
70 lbs (31.7 kg) 317mg 697.5mg (3 × 250mg) 951mg (4 × 250mg) every 8-12 hours
80 lbs (36.3 kg) 363mg 798.5mg (3 × 250mg) 1089mg every 8-12 hours
90 lbs (40.8 kg) 408mg 897.5mg 1224mg (5 × 250mg) every 8-12 hours
100 lbs (45.4 kg) 454mg (2 × 250mg) 999mg (4 × 250mg) 1362mg every 8-12 hours
120 lbs (54.4 kg) 544mg (2 × 250mg) 1197mg (5 × 250mg) 1632mg every 8-12 hours
150 lbs (68 kg) 680mg 1496mg (6 × 250mg) 2040mg (8 × 250mg) every 8-12 hours

What is Keflex (Cephalexin) used for in dogs?

skin infections (pyoderma) urinary tract infections bone infections wound infections

How to give Keflex to your dog

Cephalexin can be given with or without food, but giving with food reduces stomach upset. Complete the entire prescribed course, even if your dog seems better. For skin infections, treatment often needs to continue for 3-4 weeks or longer.

Available Forms

capsule, tablet, liquid suspension

Give with Food?

Yes — give with food

Side effects of Keflex in dogs

Common side effects

nausea
vomiting
diarrhea
decreased appetite

Serious side effects

  • allergic reaction (hives, swelling)
  • severe diarrhea
  • blood in stool
  • seizures (rare, very high doses)

When to call the vet

Call your vet immediately if your dog shows any of these signs:

  • Signs of allergic reaction (facial swelling, hives, difficulty breathing)
  • Severe or bloody diarrhea
  • Vomiting that does not resolve
  • No improvement after 3-5 days
  • Rash or skin reaction develops

Related Medications for Dogs

Fluoroquinolone antibiotic

Baytril

Enrofloxacin

For Urinary tract infections

View dosage chart
Antibiotic (Penicillin)

Amoxil

Amoxicillin

For bacterial infections

View dosage chart
Antibiotic (Tetracycline)

Vibramycin

Doxycycline

For tick-borne diseases (Lyme, ehrlichiosis)

View dosage chart
Antibiotic / Antiprotozoal

Flagyl

Metronidazole

For diarrhea

View dosage chart

Sources & References

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Cephalexin.

Frequently Asked Questions

What is cephalexin used for in dogs?
Cephalexin is one of the most commonly prescribed antibiotics for dogs. It is especially effective for skin infections (pyoderma), urinary tract infections, wound infections, and bone infections. It works by killing bacteria by disrupting their cell wall formation.
How much cephalexin do I give my dog?
The standard dose is 22 mg per kilogram of body weight, given every 12 hours. For example, a 50 lb (23 kg) dog would typically receive 500 mg twice daily. Your vet may adjust the dose based on the type and severity of infection.
How long should a dog take cephalexin?
Treatment duration depends on the infection. Simple urinary tract infections may need 7-14 days. Skin infections (pyoderma) often require 3-4 weeks or even longer for deep infections. Always complete the full prescribed course.
Is cephalexin safe for dogs?
Cephalexin is considered very safe for dogs and is one of the most commonly prescribed veterinary antibiotics. The most common side effects are mild GI upset (nausea, diarrhea). Serious allergic reactions are rare but possible, especially in dogs with known penicillin allergies.

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