Last updated: June 19, 2026
Cephalexin Dosage Calculator for Dogs
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Quick Answer
The Cephalexin Dosage Calculator for Dogs estimates the antibiotic dose as Dose per administration (mg) = body weight (kg) × 15 mg/kg, given twice daily (every 12 hours). For a 250 mg/5 mL suspension (50 mg/mL), the liquid volume is the dose in mg divided by 50. For example, a 25 kg dog needs 375 mg (7.5 mL) per dose, or 750 mg per day. Severe infections may require 22–30 mg/kg under veterinary supervision. Cephalexin is a prescription medication, so this tool is an educational dosing aid only — the exact dose, frequency, and duration must be set by a veterinarian.
A dog's standard cephalexin dose equals its weight in kilograms times 15 milligrams per kilogram, given twice daily. For example, a 25 kilogram dog needs about 375 milligrams per dose, or 750 milligrams per day. Always confirm the dose with your veterinarian.
Key Takeaways
- Dose per administration (mg) = dog weight (kg) × 15 mg/kg — a 25 kg dog gets 375 mg
- The standard canine schedule is 15 mg/kg twice daily (every 12 hours)
- Liquid (250 mg/5 mL = 50 mg/mL): mL per dose = dose in mg ÷ 50 — 375 mg equals 7.5 mL
- Weigh in pounds? Divide by 2.2046 to convert to kilograms before dosing
- Severe infections may need 22–30 mg/kg — only under veterinary supervision
- Cephalexin is prescription-only — this calculator is a dosing aid, not a substitute for veterinary advice
Creators
Dharmendra SinghReviewers
Creators
Dharmendra SinghReviewers
Formula
Dose per administration (mg) = Dog weight (kg) × 15 mg/kg
Where:
- D_mg=Dose per administration(mg)
- W_kg=Dog body weight(kg)
Worked Examples
25 kg dog (standard 15 mg/kg)
A medium-large dog (e.g. a Labrador) at the standard rate for a typical skin or urinary infection.
- 1Dose = 25 kg × 15 mg/kg = 375 mg per administration
- 2Daily total = 375 mg × 2 doses = 750 mg/day
- 3Liquid (250 mg/5 mL = 50 mg/mL) = 375 ÷ 50 = 7.5 mL per dose
- 4Tablets (250 mg) = 375 ÷ 250 = 1.5 tablets per dose
50 lb dog (weighed in pounds)
A dog weighed in pounds — the calculator converts to kilograms before dosing.
- 1Convert weight: 50 lbs ÷ 2.2046 = 22.7 kg
- 2Dose = 22.7 kg × 15 mg/kg = 340 mg per administration
- 3Tablets (250 mg) = 340 ÷ 250 = 1.36 tablets per dose
10 kg small dog
A small dog (e.g. a Beagle-sized pet) where a liquid suspension is often easier to dose accurately.
- 1Dose = 10 kg × 15 mg/kg = 150 mg per administration
- 2Daily total = 150 mg × 2 doses = 300 mg/day
- 3Liquid = 150 ÷ 50 = 3.0 mL per dose
Introduction
The Cephalexin Dosage Calculator for Dogs estimates the antibiotic dose from your dog's weight using the standard canine rate, then converts it into a liquid volume or tablet count. Cephalexin (cefalexin, brand name Keflex) is a first-generation cephalosporin and one of the most commonly prescribed antibiotics in veterinary medicine. The usual dose is 15 mg/kg twice daily, so the dose per administration is simply weight (kg) × 15 mg/kg. This tool is an educational dosing aid, not veterinary advice — cephalexin is a prescription medication, and only your veterinarian can diagnose your dog and set the correct dose, route, and duration. For related tools, see our Benadryl dosage for dogs calculator and cephalexin for cats dosage calculator.
Important Safety Information
Antibiotic dosing is a medical decision. An incorrect dose, or using an antibiotic when it isn't needed, can harm your dog and promote resistant bacteria. Please read this before relying on the numbers from this calculator.
Prescription only: cephalexin requires a veterinary prescription — never start, stop, or change an antibiotic without your vet
Confirm the diagnosis: antibiotics only treat bacterial infections; they do nothing for viral illness
This calculator uses the standard 15 mg/kg rate — your vet may prescribe a higher rate (up to ~30 mg/kg) for severe infections
Never use leftover antibiotics or a medication prescribed for another pet or person
Finish the full course: stopping early drives antibiotic resistance and relapse
Treat any allergic reaction as an emergency: facial swelling, hives, or difficulty breathing need immediate care
This calculator does not replace professional veterinary judgement. Always confirm every dose with your veterinarian before giving it to your dog.
Cephalexin Dosage Chart for Dogs
Reference chart based on the standard veterinary dose of 15 mg/kg twice daily, as documented in the Merck Veterinary Manual. For severe or deep infections, vets may increase the rate to 22–30 mg/kg under supervision.
| Dog Weight (kg) | Dog Weight (lbs) | Dose at 15 mg/kg (mg) | Daily Total (mg) | Tablets 250 mg | Liquid 50 mg/mL (mL) |
|---|---|---|---|---|---|
| 5 | 11 | 75 | 150 | 0.3 | 1.5 |
| 10 | 22 | 150 | 300 | 0.6 | 3.0 |
| 15 | 33 | 225 | 450 | 0.9 | 4.5 |
| 20 | 44 | 300 | 600 | 1.2 | 6.0 |
| 25 | 55 | 375 | 750 | 1.5 | 7.5 |
| 30 | 66 | 450 | 900 | 1.8 | 9.0 |
| 35 | 77 | 525 | 1050 | 2.1 | 10.5 |
| 40 | 88 | 600 | 1200 | 2.4 | 12.0 |
| 45 | 99 | 675 | 1350 | 2.7 | 13.5 |
| 50 | 110 | 750 | 1500 | 3.0 | 15.0 |
How Cephalexin Dosing Works for Dogs
Cephalexin is a beta-lactam antibiotic that kills bacteria by disrupting cell-wall synthesis. It is time-dependent, meaning efficacy relies on keeping blood levels above the minimum inhibitory concentration (MIC) — which is why consistent twice-daily dosing matters. Per veterinary pharmacology references, the standard dose is 15 mg/kg every 12 hours.
Dose per administration (mg) = weight (kg) × 15 mg/kg
- Standard schedule:
twice daily (every 12 hours)
- Severe infections:
vets may use 22–30 mg/kg, and/or longer courses, under supervision
- Liquid suspension:
250 mg per 5 mL = 50 mg/mL, so mL per dose = dose (mg) ÷ 50
- Tablets:
commonly 250 mg, 500 mg, and 750 mg — tablets per dose = dose (mg) ÷ tablet strength
- Course length:
typically 7–28 days depending on the infection — always finish it
How to Give Cephalexin to Your Dog
Cephalexin is well tolerated by most dogs. Consistent timing and good technique keep blood levels steady and the antibiotic effective.
Give with or just after food to reduce stomach upset
Space doses evenly — every 12 hours for the standard twice-daily schedule
For liquid, shake the bottle well and measure with the supplied oral syringe, not a kitchen spoon
Tablets can be hidden in a treat or pill pocket; ask your vet before crushing extended formulations
Always provide access to fresh water
Wash your hands after handling the medication
Set phone alarms for each dose. Even spacing (e.g. 8 am / 8 pm) keeps the drug above its effective concentration and improves the chance of clearing the infection.
What to Do About a Missed Dose
Missing an occasional dose is common during a multi-week course. Handle it safely rather than doubling up.
Give the missed dose as soon as you remember
If it is almost time for the next dose, skip the missed one and resume the normal schedule
Never give two doses at once or 'catch up' — doubling raises the risk of vomiting and other effects
If your dog vomits a dose shortly after taking it, do not automatically re-dose — call your vet
Keep a simple dosing log so you do not lose track over a long course
Common Uses of Cephalexin in Dogs
Cephalexin is effective against most gram-positive cocci and some gram-negative bacteria common in canine infections. It is a first-line antibiotic for many skin and soft-tissue infections.
- Skin infections (pyoderma):
Staphylococcus pseudintermedius — the most common indication
- Wound infections:
surgical sites, bite wounds, and lacerations
Urinary tract infections caused by susceptible bacteria
- Bone infections (osteomyelitis):
cephalexin penetrates bone well
- Soft-tissue infections:
abscesses and cellulitis
Some ear and respiratory infections, at the vet's discretion
Side Effects, Cautions, and When to Call the Vet
Cephalexin is one of the safest antibiotics for dogs, and side effects are usually mild — but know which signs are emergencies.
- Common (mild):
vomiting, diarrhoea, drooling, or reduced appetite — giving with food usually helps
- Allergy/penicillin cross-reactivity:
avoid in dogs with a known cephalosporin or penicillin allergy (~5–10% cross-react)
- Kidney disease:
cephalexin is cleared by the kidneys, so impaired dogs may need an adjusted dose
- Drug interactions:
tell your vet about every medication and supplement (e.g. probenecid raises blood levels)
- Pregnancy/nursing:
generally considered low-risk but use only under veterinary direction
Call your veterinarian immediately for hives, facial swelling, difficulty breathing, persistent vomiting, weakness, or collapse — these can signal a serious allergic reaction.
Storage, Handling, and Key Terms
Correct storage keeps the medication effective for the full course. The glossary explains the shorthand you may see on a prescription label.
| Term / topic | What it means |
|---|---|
| Liquid suspension storage | Refrigerate after reconstitution and discard after the period on the label (often ~14 days). |
| Tablet storage | Room temperature, away from moisture and direct light; keep out of reach of pets and children. |
| mg/kg | Milligrams of drug per kilogram of body weight — the dosing rate. |
| q12h / BID | Every 12 hours / twice daily — the standard cephalexin schedule for dogs. |
| Keflex | A common brand name for cephalexin; generic cephalexin is pharmacologically identical. |
| MIC | Minimum inhibitory concentration — the drug level needed to suppress the target bacteria. |
| Pyoderma | Bacterial skin infection, the most common reason cephalexin is prescribed for dogs. |
Quick Reference Card
Cephalexin for Dogs — Quick Reference
Quick reference • Cephalexin Dosage Calculator for Dogs
Dose (mg) = Weight (kg) × 15 • Liquid (mL) = Dose ÷ 50 • Daily = Dose × 2Valid range: Standard 15 mg/kg twice daily; up to 22–30 mg/kg (vet-directed)
Common Values
⚠ Watch Out
- •Prescription medication — always confirm the dose, frequency, and duration with your veterinarian
- •Never use a cat's or a person's cephalexin, or any leftover antibiotic
- •Finish the entire course; stopping early drives resistance and relapse
- •Stop and call your vet for hives, facial swelling, breathing trouble, or persistent vomiting
Pro Tips
- →Give with food and at evenly spaced times (every 12 h) to improve tolerance and efficacy
- →Measure liquid with the supplied oral syringe, never a kitchen spoon
- →Hide tablets in a treat or pill pocket; set alarms and keep a dosing log
- →Ask your vet before crushing tablets or switching between tablet strengths
FAQs
What is the cephalexin dose for dogs?
The standard dose is 15 mg/kg (about 7 mg/lb) of body weight, given twice daily. For example, a 25 kg dog receives 375 mg per dose. For severe or deep infections, veterinarians may prescribe up to 22–30 mg/kg twice daily. This calculator uses the standard 15 mg/kg rate.
How do I calculate my dog's cephalexin dose?
Multiply your dog's weight in kilograms by 15 mg/kg: Dose = Weight (kg) × 15. If you weigh your dog in pounds, divide by 2.2046 to get kilograms first. To convert to liquid, divide the milligram dose by 50 (for a 250 mg/5 mL suspension). This calculator does all of this automatically.
How much liquid cephalexin should I give my dog?
The common suspension is 250 mg per 5 mL, which is 50 mg/mL. Divide the prescribed milligram dose by 50 to get the volume in mL. A 375 mg dose, for example, is 375 ÷ 50 = 7.5 mL. Always measure with the oral syringe provided, not a kitchen spoon.
How long should dogs take cephalexin?
Duration depends on the infection: simple skin infections typically 7–14 days, deep pyoderma often 4–6 weeks, urinary infections about 10–14 days, and bone infections 6–8 weeks. Always complete the full course your vet prescribes, even if your dog seems better.
Can I give my dog cephalexin with food?
Yes. Giving cephalexin with food can reduce gastrointestinal side effects such as vomiting and diarrhoea, and food does not significantly reduce absorption. Many owners hide tablets in a treat or pill pocket.
What happens if I miss a dose?
Give the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed one and return to the regular schedule. Never give two doses at once to make up for a missed one, as this increases the risk of side effects.
Is cephalexin the same as Keflex?
Yes. Keflex is a brand name for cephalexin, and generic cephalexin is pharmacologically identical — the same active ingredient at the same strengths. Only give a product that your veterinarian has prescribed for your dog.
Can cephalexin cause side effects in dogs?
Most side effects are mild: vomiting, diarrhoea, drooling, or reduced appetite, especially on an empty stomach. Serious allergic reactions (hives, facial swelling, difficulty breathing) are rare but are emergencies requiring immediate veterinary care.
Can I give my dog cephalexin prescribed for a cat or a person?
No. Never use another animal's or a person's medication. The strength and formulation differ, and dosing must match your specific dog. Only give cephalexin that your veterinarian has prescribed for your dog.