10 Facts You Should Know About Cephalexin for Dogs


Taylor A Ritz

Cephalexin is a broad-spectrum antibiotic used to treat some infections in dogs. An antibiotic can be used to treat many bacterial infections and cephalexin is often favored due to the relatively small number of side effects. Cephalexin is also known as Keflex, Keftab, Rilexine, Sporidex, and Biocef.

1. What Is Cephalexin?

As mentioned above, cephalexin is an antibiotic that treats many different bacterial infections in dogs. An antibiotic is a medication that fights bacterial infections. Antibiotics fight bacterial infections by disrupting bacteria’s biological processes and preventing them from proliferating.

Cephalexin is a cephalosporin, a type of antibiotic similar to penicillin.

2. How Does Cephalexin Work?

Bacteria are single-celled organisms found throughout the planet. Some are helpful, while others can be harmful. Bacterial infections occur when a harmful strain of bacteria enters and reproduces inside your – or your dog’s – body.

Cephalexin works by causing cell wall rupture in the membrane of the bacterial cells. The antibiotic inhibits the bacterial cell from synthesizing the peptidoglycan layer of the cell wall. 

3. What Kind of Bacteria is Cephalexin Effective Against?

Bacterial infections come in two types: gram-positive and gram-negative. The most significant difference between gram-positive and gram-negative bacteria is in their membranes; gram-positive bacteria have a thick membrane, while gram-negative bacteria have a thinner membrane.

Fortunately, cephalexin has proven effective against infections with either gram-positive or gram-negative bacteria, making it a very useful antibiotic. It is worth noting that the Merck Veterinary Manual considers cephalexin an active agent against gram-positive bacteria; however, it is only moderately active against gram-negative bacteria. 

4. Can Cephalexin Treat a Dog Bite?

Veterinarians prescribe cephalexin for many reasons. If your dog gets into a fight and experiences a puncture wound, your veterinarian is likely to prescribe cephalexin. This should prevent an infection from occurring.

5. Is Cephalexin Approved by the Food and Drug Administration?

The Food and Drug Administration, or FDA, has not approved the use of cephalexin on dogs. However, veterinarians can prescribe cephalexin for use in dogs under “extra-label” provisions. Extra label provisions are a result of the Animal Medicinal Drug Use Clarification Act of 1994 (also known as AMDUCA). This piece of legislation allows veterinarians to prescribe an FDA-approved drug in a manner that is not in accordance with the drug’s label.

For example, veterinarians can use a drug on a different species, for a different health issue, at a different dosage, or via a different route than was is expressly stated on the drug’s label. In summary, the AMDUCA allows veterinarians to use medicines in ways not approved of by the FDA when the health of an animal is threatened.

So, even though cephalexin is not formally approved by the FDA for use in treating bacterial infections in dogs, it is often prescribed for exactly that purpose. 

6. What Kinds of Infections Can Cephalexin Treat?

Cephalexin is a broad-spectrum antibiotic. This means cephalexin can be effective against a multitude of bacterial infections. Some of these include:

  • E. coli
  • Haemophilus influenza
  • Proteus mirabilis
  • Streptococcus pneumonia
  • Streptococcus pyogenes 

Veterinarians often give dogs cephalexin for issues with the skin, urinary tract, joint, ear, or respiratory infections.

7. When Will Your Dog’s Vet Prescribe Cephalexin?

If your veterinarian suspects that your dog has a bacterial infection, she will test the infection to determine what kind of bacteria have infiltrated your canine companion. In the event of a skin infection, a licensed veterinarian can take a skin scraping to test the bacteria; otherwise, they will likely use a blood test.

Based on the findings, your dog’s veterinarian can prescribe cephalexin or penicillin to eliminate the bacteria and, subsequently, the infection.

8. How Much Cephalexin Should You Give Your Dog?

A typical dosage of cephalexin in canines is 10 to 15 milligrams for each pound of body weight. This means a 50-pound dog would receive about 500 milligrams of cephalexin in a dose. 

You should always consult your veterinarian with questions and concerns regarding medicine. Follow your veterinarian’s instructions to have your dog feeling fit and healthy as quickly as possible.

9. How Often Should You Give Your Dog Cephalexin?

Follow your veterinarian’s instructions regarding how often to give your dog cephalexin. It is very important to follow the antibiotic procedure your veterinarian gives you. Cephalexin is typically given to dogs two to three times each day. It’s vital to be consistent in these daily dosage times.

If you are late with a dose, give your dog their cephalexin as soon as possible, unless it is nearly time for your dog’s next dose of the drug; do not give your dog two doses of the antibiotic at one time. Consistency is key. Most prescriptions for cephalexin suggest an administration regiment of 7 to 10 days. 

10. What Are Some Considerations For Giving Your Dog Cephalexin?

Cephalexin is available in liquid, tablet, and capsulated variations. Though cephalexin is also available for use in humans, you should never give cephalexin intended for a human to your dog. The ingredients that make up a cephalexin tablet intended for a human are likely different than those made for a dog. Inactive ingredients found in your medication may well be toxic to your dog.

As with any drug, your dog may experience side effects from taking cephalexin. Dogs may experience nausea, vomiting, or diarrhea after taking this medication. Your veterinarian may tell you to give your dog the antibiotic with food to alleviate some of these possible discomforts.

Other potential side effects include drooling, excess panting, and excitability.

Dogs that are pregnant or nursing should not be given cephalexin. You should not give the drug to dogs that have been diagnosed with kidney failure. Any dog that has ever experienced a seizure, especially those diagnosed with epilepsy, should also avoid this antibiotic.

Anyone, human or canine, who has experienced bad allergic reactions to penicillin or other antibiotics should take great care. Cephalexin has been linked to lameness and other motor issues in large breed dogs in extremely rare cases.

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Taylor Ritz

Taylor has a Bachelor of Science in Animal Science. She is a former zookeeper and animal trainer. She has her own dog, Dobby, with whom she has bicycled across the U.S. and thru-hiked the Long Trail.

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