Cephalexin is an oral antibiotic that may be prescribed by veterinarians for certain bacterial infections in dogs, especially bacterial skin infections such as pyoderma. It belongs to the cephalosporin class of antibiotics and acts by disrupting the formation of the bacterial cell wall, thereby inhibiting the growth of susceptible bacteria.
Cephalexin should only be used as a veterinarian-prescribed antibiotic, like any other antibiotic. It is not a good choice for all infections, and it should not be used for non-bacterial conditions. Antibiotics are not always needed, and giving them when they are not needed can delay proper care and contribute to antimicrobial resistance.
What Is Cephalexin?
Cephalexin is a beta-lactam antibiotic in the cephalosporin class. It is frequently used in dogs to treat pyoderma and other bacterial infections of the skin. Some veterinarians may also prescribe it off-label for certain urinary tract infections or other bacterial conditions when they believe it is warranted.
RILEXINE® chewable tablets are a veterinary formulation of cephalexin for the treatment of secondary superficial bacterial pyoderma in dogs due to susceptible strains of Staphylococcus pseudintermedius.
What Is Cephalexin Used for in Dogs?
A veterinarian may prescribe cephalexin if they suspect or confirm that a bacterial infection is present and is likely to respond to this type of antibiotic. While cephalexin is most often associated with bacterial skin infections, its use depends on the dog’s diagnosis, health history, and the bacteria involved.
Veterinarians might consider cephalexin for conditions such as:
- Skin infections caused by bacteria
- Superficial pyoderma
- Infected wounds, when indicated
- Certain soft tissue infections
- Some urinary tract infections, depending on the case
- Post-operative infections where the bacteria are likely to be susceptible
Cephalexin is not effective against all bacteria. Sometimes, your veterinarian may suggest a culture and sensitivity test to identify the bacteria and select the most suitable antibiotic. Appropriate culture and susceptibility tests should be performed prior to therapy whenever possible, and therapy should be adjusted accordingly.
Cephalexin for Dogs: Skin Infections
One of the most common reasons cephalexin may be prescribed for dogs is skin infection. Signs of bacterial skin infections include redness, pustules, scabs, itching, hair loss, flaky skin, odor, or irritated patches. These infections can occur when allergies, fleas, moisture, wounds, skin folds, or other issues break down the skin barrier.
Cephalexin can treat susceptible bacterial skin infections, but the underlying cause must still be addressed. If a dog has recurring pyoderma, the veterinarian may search for allergies, parasites, hormonal disease, immune problems, or incomplete response to prior treatment.
Cephalexin for Dogs Dosage
The right amount of cephalexin for dogs depends on several factors, including the dog’s weight, the type and severity of infection, kidney function, medical history, and the particular product being used. Always follow the veterinarian’s prescription label and do not try to calculate the dose yourself at home.
For reference, the FDA label for RILEXINE chewable tablets specifies a dose of 22 mg/kg, or 10 mg/lb, twice daily for 28 days for its labeled indication: secondary superficial bacterial pyoderma due to susceptible Staphylococcus pseudintermedius. The Merck Veterinary Manual lists a much broader cephalexin dose for dogs of 15–45 mg/kg by mouth every 6–12 hours, but this does not replace a veterinarian’s prescribed dose.
The amount prescribed for a dog may vary from these references depending on the diagnosis, severity of the infection, formulation, and veterinarian’s discretion. Do not give a dog cephalexin that was prescribed for another pet or person.
How Is Cephalexin Given to Dogs?
Cephalexin is taken by mouth and may be available as a capsule, chewable tablet, or liquid. It may be given with or without food. Your veterinarian may recommend giving the medication with a small amount of food if your dog vomits or seems nauseated after taking it. Liquid cephalexin should be shaken well and measured carefully.
It is important to give the medication exactly as directed and to complete the full prescribed course, even if your dog looks better before the medication is finished. Stopping antibiotics early can allow some bacteria to survive, which can make the infection more difficult to treat.
How Quickly Does Cephalexin Work?
Cephalexin starts working in the body fairly quickly, but it may take a couple of days before you notice visible improvement. VCA says the medication will take one to two hours to take effect, but outward results may not be noticeable right away.
Depending on the infection being treated, owners may observe a gradual improvement in redness, swelling, discharge, odor, or discomfort. If the symptoms do not improve within the time period given by the veterinarian, or if they get worse at any time, the dog should be rechecked.
What to Expect During Treatment
During treatment, your veterinarian may ask you to keep track of your dog’s symptoms, appetite, energy level, skin, digestion, and overall comfort. Some dogs do very well, but others need follow-up visits, longer treatment, topical therapy, or additional testing.
Skin infections may also be treated with medicated shampoos, topical antiseptics, allergy management, flea prevention, or other measures to treat the underlying cause. Antibiotics may help with the bacterial aspect of the problem, but they might not stop the infection from coming back if the trigger is still there.
Potential Side Effects of Cephalexin in Dogs
Most dogs do very well with cephalexin, but side effects can happen. The most common adverse effects involve the digestive tract. These may include:
- Loss of appetite
- Vomiting
- Diarrhea
- Nausea
- Excess salivation
- General stomach upset
VCA lists gastrointestinal upset, including lack of appetite, vomiting, and diarrhea, as possible side effects. Allergic-like reactions that include fever, rash, difficulty breathing, or pale gums should be treated as urgent.
When to Contact Your Veterinarian
If your dog is taking cephalexin and vomits, has diarrhea, has a poor appetite, seems unusually tired, or shows any symptom that appears concerning, contact your veterinarian.
Call urgently if your dog shows signs of an allergic reaction or serious adverse reaction, such as:
- Facial swelling
- Hives or rash
- Shortness of breath
- Pale gums
- Severe weakness or collapse
- Severe vomiting or diarrhea
- Refusal to eat
- Sudden worsening of symptoms
VCA advises discontinuing cephalexin and contacting your veterinarian immediately if serious reactions happen. The RILEXINE label says that dogs with a known hypersensitivity to cephalexin or other beta-lactam antibiotics should not be given it.
Which Dogs Should Use Cephalexin Cautiously?
Not all dogs may be good candidates for cephalexin. It should not be used in dogs known to be allergic to cephalexin, cephalosporins, or certain related beta-lactam antibiotics unless specifically directed by a veterinarian.
Dogs with kidney dysfunction, pregnant or nursing dogs, or dogs that have been sensitive to other antibiotics may require extra caution. Pets with kidney disease may require more frequent monitoring or dose changes.
Can I Give My Dog Human Cephalexin?
Dogs should only take cephalexin if it has been prescribed by a veterinarian. Human medication may have the wrong dosage, formulation, inactive ingredients, or instructions for a dog. The prescription should be calculated according to the dog’s weight, diagnosis, and health status, even if the active ingredient is the same.
Do not give leftover cephalexin from another person, another pet, or an old prescription. The infection may not be bacterial, the antibiotic may not be appropriate for the bacteria involved, or the dose and duration may be inappropriate.
What If I Miss a Dose?
If you miss a dose of cephalexin, follow the instructions from your veterinarian or the medication label. VCA usually suggests administering the missed dose when you remember and then continuing with the normal schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give two doses at the same time.
How Should Cephalexin Be Stored?
Store cephalexin as directed on the product label and by your veterinarian. VCA recommends that cephalexin be stored in a tightly closed container, away from light, at room temperature of 59°F to 86°F. Oral suspensions are usually refrigerated and thrown away after 14 days.
Some chewable tablets are made to taste good, so keep them locked up and out of reach of dogs, cats, and children. The RILEXINE label warns that pets may eat more than the recommended dose if they can access the tablets, which could lead to overdose.
Why It Is Important to Use Antibiotics Properly
Antibiotics are useful drugs, but they need to be used wisely. The RILEXINE label states that prescribing antibacterial drugs where a bacterial infection is not proven or strongly suspected is unlikely to benefit the animal and may increase the risk of drug-resistant pathogens.
Pet owners can encourage responsible use of antibiotics by using them as prescribed, completing the entire course of medication, not sharing antibiotics between pets, and returning for rechecks when recommended.
Using Cephalexin Safely: What Dog Owners Should Remember
If the infection is bacterial and the organism is expected to be susceptible, cephalexin may be an effective antibiotic for dogs. It is most often used for bacterial skin infections such as pyoderma, and veterinarians may also use it in other cases when appropriate.
The right dosage, treatment length, and monitoring plan depend on the dog’s condition and should always come from a veterinarian. While many dogs tolerate cephalexin well, side effects and allergic reactions are possible.
If your dog has a suspected infection, do not use leftover antibiotics or human medication. Contact your veterinarian for an exam, diagnosis, and a treatment plan that fits your dog’s specific needs.
Disclaimer: This information is for general informational purposes only and is not intended as veterinary or medical advice. It should not be used as a substitute for professional care. Please consult a licensed veterinarian for diagnosis, treatment, and guidance regarding your animal’s health.