Cephalexin Killed My Dog

It might be that you had self-medicated your dog sometimes back with antibiotics without the vet’s prescription and your dog responded well. Unfortunately, your dog later developed an infection and you thought of treating him with Cephalexin but everything didn’t turn out right, and you ended up losing your dog.

I can empathize with you having lost my dog sometime back through an accident. It is a challenging time and as a loving paw parent, the wisest thing to do is understand more about this drug to avoid similar mistakes in the future and help a friend or two with the information.

In this article, you will understand more about Cephalexin, and possible reasons that might have contributed to the death of your pet.  

What is Cephalexin?

Cephalexin is an antibiotic often prescribed to treat skin infections in dogs and cats. A vet may also prescribe it for other types of infections.

It works effectively as a broad-spectrum antibiotic that kills a variety of strains. It is a first-generation medication made from cephalosporin.

The medication is sold in a variety of stores under numerous brand names, including Rilexine, Keflex, Biocef, Sporidex, and Keftab. It is available as pills, capsules, or even liquid.

This medication has received FDA (U.S. Food & Drug Administration) approval for use in both people and dogs, but not in any other species. In certain circumstances, the FDA does permit veterinarians to administer and use human products containing this drug in animals.

However, in some situations, veterinarians can legally prescribe specific human medications to animals. Because this use isn’t disclosed on the medication label, it is known as extra-label or off-label use.

Cephalexin should only be used with a prescription. If your dog is sick, your veterinarian may perform several tests, including blood tests, to identify the specific bacterial strain responsible. The vet will only recommend the drug if he discovers that the particular bacteria will be killed by cephalexin.

How Does Cephalexin Work?

Cephalexin is a drug that belongs to the cephalosporin class of antibiotics. Since bacteria are living things, they need nutrients like proteins. Cephalexin works by inhibiting the synthesis of proteins in the bacterial cell wall leading to their death. This explains why cephalexin effectively kills gram-positive bacteria.

However, cephalexin does not kill all types of bacteria. Additionally, it is ineffective against parasites, fungi, and viruses. It survives through the intestines when consumed orally and reaches the bloodstream with ease. It can thus reach the intended location easily.

It’s important to use antibiotics exactly as prescribed by your veterinarian because improper use of antibiotics including cephalexin can result in the development of bacterial resistance.

Cephalexin Killed My Dog

Below are some of the reasons why a dog can be killed by Cephalexin;

Underlying Health Conditions

Cephalexin can cause adverse side effects if a dog had other health issues. It is advisable to discuss with your vet It is crucial to discuss any past illnesses with a veterinarian before starting Cephalexin medication because these health issues might not be immediately obvious.

An allergic reaction

Certain dogs may experience an allergic response to cephalexin leading to severe side effects or even death. The signs of an allergic reaction can include difficulty breathing, swelling, hives, and vomiting.

Interaction with other medication

If a dog is under medication, there is a high chance of the drugs interacting with Cephalexin and the results can be fatal. You need to notify your vet of any drug that your dog is taking, even if it is a vitamin supplement.


A veterinarian should recommend specific dosages of the powerful drug Cephalexin to be administered. Giving your canine too much Cephalexin could have fatal consequences.

Cephalexin dosage

The appropriate dose will be suggested by your veterinarian based on a variety of factors. They will also take into account the animal’s age, breed, weight, and overall health status. The dosage will also vary depending on what illness your canine is suffering from, such as whether it is a skin infection or a bladder infection, and any other medications the dog is taking.

In general, 10 to 15 mg of cephalexin per pound of your pet’s weight is recommended. Normally, this medicine is administered every 8 to 12 hours for a few days, but depending on the individual circumstances of your pet’s condition, your vet might suggest a different dosage. Even if they appear to be getting better or their physical symptoms disappear fast, your pet should always complete their entire prescription.

Your dog can take cephalexin with or without meals. Giving it with a small meal may lessen nausea and other digestive issues.

Missed a Dose?

Cephalexin should be administered to your pet as soon as you remember if you forget to do so. If your next dose is approaching, skip the missed one and go back to your regular dosing plan. Give no additional or double doses.

What Does Cephalexin Treat In Dogs?

  • Urinary tract (UTI)
  • Skin and soft tissue, such as hotspots and pyoderma
  • Bone
  • Respiratory tract
  • Ear (otitis)
  • Bone infections
  • Heart valve infections
  • Haemophilus influenza
  • Klebsiella pneumonia
  • Proteus mirabilis

Only Use Cephalexin for Dogs by Prescription

Avoid giving your dog Cephalexin without a vet prescription. Below are some of the reasons why it is important to follow a vet’s prescription when giving your dog Cephalexin.

1. Allergies

There’s a possibility that your canine has an allergy to the medication.  

2. Underlying health condition

Some underlying diseases can be made worse by taking Cephalexin. So, it’s better to take your dog to a vet because he will do a thorough screening before administering any drug.

3. Medications

If your dog is already under medication, there is a high possibility that Cephalexin will react with them. So, it’s advisable to inform your vet of any medicine that your dog is taking. 

4. Bacterial Resistance

You might not know the actual dose that is recommended to treat your dog. Giving your dog an incomplete dose can lead to the development of bacterial resistance. This leads to the re-occurrence of the infection.

A Guide for Giving Cephalexin to Your Furry Friend

  • Observe the dosage and dosing recommendations provided by your veterinarian.
  • Cephalexin can be taken with or without meals. Your veterinarian might suggest giving your canine this antibiotic with food. This could lessen negative impacts.
  • Once your pet begins taking any medicine, keep an eye on them. Make sure they don’t experience any negative side effects or medication allergies.
  • Make sure your dog takes the full course of Cephalexin treatment. This will aid in the total elimination of bacterial illness.
  • Don’t administer the medicine to any additional pet. The dose and strength are based on the dog’s evaluation by your veterinarian.

Precautions Regarding Cephalexin for Dogs

Follow the precautions below before giving Cephalexin to your dog;

  • Do not give the Cephalexin to any animals with a penicillin or cephalosporin allergy.
  • Do not give Cephalexin to nursing, pregnant, or epileptic dogs. 
  • Dogs with renal failure should stay away from Cephalexin as well.
  • Larger dogs taking this drug may become lame or lazy
  • Do not combine the medication with any other medications, not even basic vitamins, or herbal remedies. Tell your veterinarian about any medications your dog is currently taking.
  • After combining it with water, store the solution in the fridge.
  • After 14 days, don’t continue using the suspension. Destroy it immediately.

Side Effects of Cephalexin for Dogs

Cephalexin usually is well tolerated by dogs, and most side effects are minor and infrequent. However, it is a good idea to keep an eye out for any changes in your dog’s health, behavior, or attitude. Any such changes should be immediately reported to your veterinarian.

The following are some of the adverse effects:

Nausea and Vomiting

Dogs may experience nausea and vomiting as one of the medication’s most frequent adverse effects. It might be the outcome of a drug allergy or an overdose. It is crucial to compare the dosage recommendations provided by the veterinarian with those on the bottle.  

Diarrhea and Pain

Another side effect due to overdose is diarrhea and stomach pains. You must give the medication after meals or with milk because it is quite a heavy drug. This ensures that the medication won’t harm the dog’s digestive tract. However, if diarrhea persists, medical experts advise stopping the drug and looking for more tolerable alternatives. It can cause a lack of appetite at times.

Behavior-Related Adverse Effects

Your dog can experience a broad range of behavioral issues, such as irritability or hyperactivity. He may have trouble breathing, and you’ll likely notice him gasping frequently. You can also notice that your dog may drool a lot.

Allergic Reaction

Check to see if your dog has a penicillin or penicillium mold allergy. There is a high possibility that your dog will be allergic to Cephalexin since it derives from the same sources. Your canine may exhibit the following signs if he is allergic to the medication:

  • Yeast infection
  • Breathing difficulties
  • Hives
  • Mucus or blood in the stool
  • Mouth or Tongue swelling
  • Rashes
  • Itching  

 Serious Diseases

Improper drug administration can also result in severe complications. If used frequently, it can lower the white cell count making your dog more prone to diseases. Other effects include hepatitis, interstitial nephritis, and kidney necrosis, among others.

Can You Give Human Cephalexin To Dogs

Cephalexin is known for curing many infections. However, it is important to know specifically what type of bacteria is affecting your dog. It is never a good idea to try treating a dog yourself with Cephalexin that you were being used by a friend. 

Similarly, it is not advised to administer any human antibiotics, such as Cephalexin, to your canine.

The dosages of medications for humans and dogs are usually different. Additionally, it could contain toxic substances like xylitol. Before giving your dog any medicine, always get advice from your vet.

When Does Cephalexin Not Work for Dogs?

Certain Bacteria

Occasionally Cephalexin can be ineffective. This happens when it cannot attack the target bacteria. Examples of such a bacteria include Enterobacter. This particular type of bacteria usually causes skin illnesses, UTIs, and eye infections. Using Cephalexin in such instances will not bring the desired results.


Also, take notice that Cephalexin will not treat any viral infections because it is ineffective against viruses.


Additionally, it has no impact on fungus-related infections like ringworm or athlete’s foot.

Testing your dog’s blood or skin is the only method to identify the disease’s origin. The veterinarian will then give the medication when it is obvious that it can successfully treat the underlying problem.

Cephalexin Smells Weird

Just be aware that Cephalexin has an odd taste. Some people say it smells like sulfur.

So don’t be alarmed if you open your prescription and scent something strange. That is normal. The medicine is in perfect condition.

Cephalexin Overdose Information

Severe vomiting, diarrhea, heavy drooling, and watery eyes are possible signs of a cephalexin overdose. Large amounts have the potential to harm the kidneys, and the liver and alter blood cell counts.

Contact your veterinarian or an animal poison control center immediately if you think your dog may have overdosed. Consultation fees often apply.

Pet Poison Helpline (855) 764-7661

ASPCA Animal Poison Control (888) 426-4435

Cephalexin Storage

Cephalexin should be kept in a controlled environment between 68 and 77 degrees Fahrenheit, though brief exposure to 59 to 86 degrees Fahrenheit is acceptable. To shield this medication from light and moisture, keep the container securely closed.

Compounded medications should be kept per the compounding pharmacy’s label.

Keep out of reach of children and pets.

Other Alternatives to Cephalexin for Dogs

There are many alternatives to Cephalexin. The most common is Penicillin substitute because it functions similarly to Cephalexin. But you can also use amoxicillin.

Dogs with skin infections sometimes do not require antibiotics or any drug for the infection to end.

Veterinarians apply a poultice close to the area to improve the blood flow. T-cells are delivered to the area by the blood for efficient recovery.


Cephalexin is an important antibiotic that can aid in your dog’s resistance to a variety of bacterial infections, but if administered incorrectly, it can have several adverse effects, death being one of them.

Without your veterinarian’s prescription, you shouldn’t give this medication. You must adhere to the dosage recommendations and finish the full course. Remember to discuss with your vet if your dog is under any medication.

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