Cephalexin for Dogs: Usage, Dosage, & Side Effects

Medications By Ben Team 6 min read May 24, 2021 20 Comments

K9 of Mine is reader-supported, which means we may earn a small commission through products purchased using links on this page. Here’s how it works.
cephalexin for dogs
vet approved graphic

Most healthy dogs have pretty robust immune systems, which are capable of eliminating bacteria that would quickly sicken you or me.

And it’s a good thing they do – given their penchant for rolling in the dirt, sniffing poop at very close range, and licking anything vaguely interesting, dogs encounter bacteria constantly.

But that doesn’t mean their immune systems are infallible. Every once in a while, they encounter a bacterial strain that is capable of evading their defenses, and setting up shop. But fortunately, modern dogs can be given antibiotics to help eliminate these pathogens and return to good health.

There are a number of different antibiotics veterinarians prescribe for sick dogs, but one of the most common is called Cephalexin (also spelled Cefalexin).

Cephalexin and Dogs: Key Takeaways

  • Cephalexin is a common antibiotic used to treat a variety of bacterial infections.
  • Cephalexin is a relatively old medication, which was first developed in 1967.
  • While it isn’t right for all dogs, cephalexin is well-tolerated by most canines.

What Is Cephalexin and What Does It Treat In Dogs?

Known by brand names such as Keflex, Cefadroxil and Biocef, cephalexin is a type of medication known as a first-generation cephalosporin. Somewhat similar to penicillin, cephalexin is better suited for treating some bacterial strains than others.

Cephalexin kills both gram-positive and some gram-negative bacteria (you can read more about the differences between these two types of bacteria here) by disrupting the way bacteria create their cell walls. Cephalexin withstands passage through the intestinal tract well, which helps ensure that it enters the bloodstream and is distributed to the target area.

Originally created in 1967, this antibiotic is used to treat people and other animals in addition to dogs. In fact, it even appears on the World Health Organization’s List of Essential Medicines, because it is such a helpful drug for treating a variety of bacterial infections.

Cephalexin is used to treat infections occurring in several different parts of the body, including the bones, skin, ears, urinary tract and lungs. It has a broad spectrum of efficacy, and is helpful for treating infections caused by the following bacteria:

  • Several different staphylococci, including Staphylococcus aureus and Streptococcus pneumonia
  • A variety of streptococci, including Streptococcus pyogenes
  • Haemophilus influenza
  • Escherichia coli
  • Klebsiella pneumonia
  • Proteus mirabilis

But cephalexin is not effective against all bacteria. For example, Pseudomonas, Enterococci, and Enterobacter are not affected by the drug.

In many cases, veterinarians may prescribe cephalexin to begin treating an infection while waiting for the results of cultures taken during an office visit.

Once the bacteria in question has been positively identified and the lab has determined which antibiotics will treat it, the vet may change the prescription to a more effective medication.

Cephalexin Is Available For Dogs By Prescription Only

Cephalexin is only available by prescription, so you’ll need to visit your veterinarian if you suspect your dog is suffering from some type of bacterial infection.

Although this is frustrating to many owners, there are three important reasons cephalexin is treated as such:

  1. Some dogs are allergic to cephalexin, while others may suffer from conditions that cephalexin can exacerbate.
  2. Some dogs may be taking medications that will interact with the antibiotic in potentially dangerous ways.
  3. Improper use, administration and disposal of antibiotics can lead to bacterial resistance, which is a serious concern in the modern world.

Accordingly, you’ll always want to follow your vet’s instructions regarding cephalexin to give your dog the best chance of recovering from the infection that is troubling her.


Cephalexin Dosage For Dogs: What’s Appropriate?

Your veterinarian will determine the proper cephalexin dosage for your pet, so you should always follow his or her instructions to the letter.

Different dosages are used to treat different bacterial strains and infections in different parts of the body, however, cephalexin is usually prescribed at a dosage of 15 mg/kg, although some vets prefer to prescribe dosages of 30 miligrams/kg in severe cases.

The medication is generally given via oral tablets, and administered every 8 to 12 hours (one to three times per day).

Your veterinarian may alter this dosage as necessary for your pet’s specific circumstances. For example, dogs suffering from kidney disease or kidney failure may require reduced doses. The duration of the treatment will also vary based on a number of factors too.

It is important to note that some bacterial infections will require multiple treatment regimens to eradicate the offending pathogens.

This will often necessitate the regular collection of cultures to monitor the bacteria, and it may be necessary for veterinarians to change the dosage or switch to another antibiotic altogether to avoid problems with antibiotic resistance.

Cephalexin is prepared in several different forms, and your vet will prescribe the one best suited for your dog’s needs. Most commonly, the medication comes in capsules which should be swallowed. However, there are chewable formulations, which are a better option for some dogs. An oral suspension (liquid) is also available as is an injectable form.

Side Effects of Cephalexin in Dogs

Most dogs tolerate cephalexin well, and side effects are generally rare and mild. However, it is always wise to watch out for changes in your dog’s health, behavior and demeanor, which should be reported to your vet promptly.

Some of the side effects include:

  • Drooling
  • Nausea
  • Vomiting
  • Excessive panting
  • Hyperactivity

Additionally, as with just about every medication available, cephalexin may cause allergic reactions in a small number of dogs. This can manifest in symptoms like skin rashes, facial swelling, or difficulty in breathing.

If you note any of these signs, contact your veterinarian immediately.  

Many veterinarians recommend giving cephalexin along with food to help reduce the likelihood of intestinal upset. However, some dogs appear to tolerate the medication well without food.

You may also want to ask your vet about incorporating a probiotic anytime you administer a broad-spectrum antibiotic to your dog. This may help ensure that your dog’s intestinal tract remains colonized by beneficial bacteria, which may help prevent diarrhea and other types of gastrointestinal distress. 

Cephalexin and Canines: General Safety Information

As with any other prescription medication, it is important to use cephalexin responsibly and to follow your veterinarian’s instructions faithfully.

Never use antibiotics or other prescription medications for other dogs in your home, unless your vet has given you permission to do so.

Always complete the entire course of medication as instructed by your vet, even if your dog’s symptoms begin to go away. Prematurely halting your dog’s medication can allow the infection to come roaring back, making treatment more difficult.

Always dispose of unused medications properly and only when your vet instructs you to do so.

 Additionally, you’ll always want to watch for signs that your dog is allergic to the medication.

Typically, allergic reactions take the form of hives or excessive itching, but in some cases allergic reactions can lead to difficulty in breathing, low blood pressure, or even cause dogs to enter a coma. Always contact your vet immediately at the first sign of an allergic reaction.

Alternative Antibiotics for Dogs

Cephalexin is not appropriate in some situations and for some dogs.

Fortunately, veterinarians have a number of other antibiotics that can be used in its place. Penicillin is one of the most common alternatives, although amoxicillin may be used in other cases.

Some dogs may not even require antibiotics at all. Warm compresses can be used in some cases to enhance blood-flow to the afflicted region. This blood helps carry oxygen and white blood cells to the area, which can help to kill the bacteria and clear the infection.


Has your vet every prescribed cephalexin for your dog? How did the treatment go? Did it clear up your dog’s infection? We’d love to hear your experiences in the comments.

Metacam for Dogs
Recommended For You

Metacam for Dogs

Written by

Ben Team

Ben is the managing editor for K9 of Mine and has spent most of his adult life working as a wildlife educator and animal-care professional. Ben’s had the chance to work with hundreds of different species, but his favorite animals have always been dogs. He currently lives in Atlanta, GA with his beautiful wife, their Rottie, and their Pyr.


Join our pup pack!

Get tons of great dog training advice and tips about gear!



Leave a Comment

Email Address
Nicole waller

My dog started taking this med soon as 10 min he started shaken scared shit out me and my husband he always been healthy update shots he got really bad allergies he bites but so bad he had bleeding so we started meds never again

Ben Team

Yikes, Nicole! That sounds scary.
Hopefully, your vet can prescribe another medication that’ll work better.
Fingers crossed for you guys!

Mikel Parkhurst

If you go to wordpress.com you will find a whole thread of pet owners who have had a problem with Cephalexin. This is what the thread is under if you’re inerested: A Warning For Dog Owners
March 14, 2008 by Katherine Coble. The thread has comments starting in 2008, as you can see, all the way up to December 10, 2020. The pet owners on K9OfMine are saying the samethings as on the thread I’ve enclosed. This appears to be more than a small number of reactions, also the reactions don’t appear to be mild. I think they would really appreciate a veterinarian to comment or at least take a look and contact the FDA. All they want is a warning to pet owners about this medication. I don’t blame them. Thank you Mikel Parkhurst, Lvt, Rvt, AAS, BS, SAVetP, Wildlife Biologist.


I have a large breed eight month old puppy Maremma sheepdog. He is now about 110 pounds. He was tick bit, and the vet prescribed 2x cephalexn 500 mg, twice daily. After the first dose taken with food he had diarrhea within a half hour. Now he is listless, and sitting outside in 82 Deg heat, and this is a cold weather mountain dog. I am discontinuing the process until I can speak with my vet come Monday.


My 11 and 1/2 year old yellow lab was prescribed this for and ear infection and it almost killed her. Big bloody pusy sores all over her body! She is very sick right now.

Ben Team

So sorry to hear that Teresa! Our fingers are crossed for your pooch.
Let us know how things go.

[email protected]

My dog is trippin mentally. The vet took a sample of a fatty blob on her forarm. 7 hours later my dog is trippin. Scared to death shaking quivering eyes wide open. Whats wrong with her. What do i do?

Ben Team

Hey, Steven. We’d strongly recommend that you contact your vet immediately.
We have no way of knowing what’s going on, but our fingers are crossed for your pooch.


My dog was given cephalexin post surgery. Would this prevent her from getting or will it treat kennel cough if she got it while there for surgery?

Ben Team

Hey, Maggie. You’ll need to discuss the issue with your vet, but Cephalexin is not typically effective at treating Bordetella (kennel cough).


My 9 year old dog has a UTI the vet put her on 750 mg of Cephalexin 2 times a day for 21 days. Is that a normal amount of time and dosage for a UTI? She weighs between 40 and 45 pounds.

unnikrishnsn nair

itching of dogs ,hot spots on the skin in many places , what is the proper treatment- internal and external treatment

Ben Team

It depends on the cause of the itching. You’ll just have to start by taking your pooch to the vet.


I’m been feeding our visiting fox who now displays an injured rear paw. I have capsules of Cephalexin and would like to know more about dosage for a fox. The capsules are 500 MG, which I realize is more than a 12 pound fox could tolerate. Any advice?

Ben Team

Hey, Carole.

I’m not sure what the cephalexin dosage for a fox would be. Honestly, I’d strongly caution you to avoid interacting with a wild fox, as they’re common rabies vectors and feeding him is just going to reduce his fear of humans (which will ultimately end up getting him into trouble).

I know you’re probably just trying to help the little guy, but I’d recommend contacting a certified wildlife rehabilitator in your area if you think he’s injured.

Best of luck!

James T

took my dog to the vet for a rash, she was 10, they did blood work and said she had cushing. gave her cephalexin for the rash, 3 weeks later she died from kidney failure. did the cephalexin cause her death

Ben Team

Hey, James. So sorry about your pooch. It’s impossible for us to know if the cephalexin contributed to your dog’s problem. I’d recommend asking your vet.

Teresa Rogers

I would say yes. It’s one of the side effects. I’m hoping my dog will survive as she was given the drug for ear infection and huge pus and blood filled sores are all over her body. Her whole neck is raw red with no fur left. There’s more that this drug has done to my sweet 11 and1/2 lab. These sores doubled her foot size. Went in between her legs and her anus is raw and pus filled the size of a side plate. The smell is very offensive.


My vet gave my Dane cephalexin for an respiratory infection (cough). A few days later my other Dane got it – but the first dog was not getting any better. She switched the meds to amoxicillin – just a day or two now, but a marked improvement for both of them!

Elaine Arnett

My vet just prescribedCephalexin in combination with Gentocin Spray for a large hot spot on my corgie’s throat and neck. She’s been taking both for four days. The affected area has dried up a lot and for the most part she has stopped scratching it. I’m quite pleased it looks so much better. The only thing I have noticed is that my corgie has way lower energy than usual. I’m attributing this to side effects of one or both meds though they were not mentioned as side effects when I just researched these two meds


Also Worth Your Time