What to Know About Antibiotics for Dogs


In this Article

  • How Do Dogs Get Sick?
  • What Are Some Common Bacterial Illnesses in Dogs?
  • What Are Some Commonly Prescribed Antibiotics for Dogs?
  • Are Human Antibiotics and Dog Antibiotics the Same?
  • What Are the Side Effects of Antibiotics in Dogs?
  • Are Antibiotics Safe for Dogs?

Antibiotics are a type of medication that destroys bacterial infections in humans and animals. They work by killing bacteria — or keeping the bacteria from growing and increasing in number. There are many different classes of antibiotics that treat a range of illnesses.

Under the guidance of a veterinarian, your dog can be treated with antibiotics for a variety of illnesses caused by bacteria.

How Do Dogs Get Sick?

Your pet comes into contact with bacteria every day. When their immune system is at its strongest, they can fight off an infection without getting sick. An infection causes symptoms when your dog’s immune system is too weak to fight it off.

The bacterial sources that contaminate your pet can include feces, contaminated water, or improperly cooked meat. These infections are more common in rescued dogs and those who have spent a lot of time in kennels. As with humans, puppies and older dogs are more likely to become sick because their immune systems are weaker than when they are in their prime. 

What Are Some Common Bacterial Illnesses in Dogs?

Bacteria are on the skin, on all surfaces, and in the air. Most of these bacteria have no impact, though some do cause illness and disease. Some common types of illness-causing bacteria in dogs include:

  • E. coli
  • Salmonella
  • Helicobacter
  • Streptococcus
  • Campylobacter
  • Clostridia 

What Are Some Commonly Prescribed Antibiotics for Dogs?

There are a few go-to drugs when it comes to what antibiotics dogs can take, depending on the illness. Amoxicillin is one of the most common. It is prescribed when an infection is suspected because it is a broad-spectrum drug — it can fight many different kinds of bacteria — and it is inexpensive.

Metronidazole for dogs is another widely used antibiotic. It is used to treat diarrhea and illnesses of the large intestine. It’s often combined with other antibiotics, and it’s prescribed for many illnesses in cats and horses as well. It can be used orally or topically, or it can be injected by your vet.

Cefazolin/cephalexin, enrofloxacin, and doxycycline are also commonly prescribed dog antibiotics. Oral antibiotics require a prescription and can be legally purchased only from a pharmacy or veterinarian. You can also find topical over-the-counter antibiotics for dogs like Neosporin in many stores. This is used to treat common scrapes and scratches.

Are Human Antibiotics and Dog Antibiotics the Same?

Though the chemical ingredients of the antibiotics are the same, veterinary-specific medicines are the safest choice for your dog. Human-dosage medications run the risk of exposing your dog to toxic ingredients.

Medications will not always be in a pure form. Some medications have artificial preservatives and flavors. One especially dangerous chemical is a sugar substitute called xylitol, which can be toxic to dogs. That is why veterinarian-prescribed medications are safest. Even with metronidazole, the U.S. Food and Drug Administration hasn’t yet approved it for use in animals. But when prescribed by a vet, it is effective for parasites and bacteria that affect dogs and humans.

What Are the Side Effects of Antibiotics in Dogs?

The side effects of antibiotics depend on which antibiotic the dog is given — and how much is taken.

General overall side effects can include:

  • Drooling
  • Nausea or vomiting
  • Loss of appetite
  • Diarrhea
  • Fatigue 

More specifically, an allergic reaction due to the use of amoxicillin and other antibiotics can lead to swelling or hives. Higher doses of metronidazole and other antibiotics can lead to:

  • Tremors
  • Muscle spasms
  • Seizures
  • Irregular heartbeat 

You should contact your veterinarian if serious side effects occur.

Are Antibiotics Safe for Dogs?

When prescribed by a veterinarian, antibiotics are safe for dogs. 

However, antibiotics can be overprescribed. Antibiotic resistance is a major concern because it is more difficult to treat antibiotic-resistant infections.

Bacterial infection resistance can also happen through:

  • Passing of bacteria to populations with weakened immune systems
  • Genetic mutations
  • Poor infection control
  • Humans giving their own personal antibiotics to pets

If you suspect that your dog may have an infection, the first step is to call your veterinarian. They will determine if the best treatment includes antibiotics.

Show Sources


American Kennel Club: “Metronidazole for Dogs.”

Centers for Disease Control and Prevention: “Antibiotic Use Questions and Answers.”

The Journal of Small Animal Practice: “Therapeutic Antibiotic Use Patterns in Dogs: Observations from a Veterinary Teaching Hospital.”

National Animal Supplement Council: “Bacterial Infections and Dogs.”

PetMD: “Can Dogs Have Amoxicillin?”

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