Antibiotics for dogs are used to treat bacterial infections and are among the most common types of medications prescribed for dogs. Learn about the most common types of antibiotics used for dogs, how to give them, and what side effects may occur.

Why Do Dogs Need Antibiotics?

Antibiotics are used to fight bacterial infections, which can occur in any part of the body, including the skin, mouth, eyes, ears, urinary tract, lungs, and other organs. Veterinarians may prescribe antibiotics for some of the following infections in dogs:

• Abscess
• Anal gland infections
  
• Pyoderma (bacterial skin infection)
• Otitis (ear infection, which may be bacterial)
• Oral or dental infection
• Eye infection
• Urinary tract infection
• Pneumonia
• Kennel cough and other upper respiratory infections (these are sometimes bacterial)
• Pancreatitis (may involve a bacterial infection)
• Diarrhea due to bacterial overgrowth
• Bacterial infections in other organs

Antibiotics are typically only prescribed if a bacterial infection is present or suspected. Some of these conditions can be viral, fungal, or sterile and will not require antibiotic therapy.

Common Antibiotics for Dogs

There are many different types of antibiotics available, as well as many different classes. Each class works differently to destroy bacteria. Some of the most common antibiotics for dogs prescribed by veterinarians include:

• Amoxicillin
• Amoxicillin/clavulanate (common brand name: Clavamox)
• Cephalexin
• Doxycycline
• Enrofloxacin (common brand name: Baytril)
• Gentamicin
• Metronidazole
• Sulfamethoxazole-trimethoprim
• Tetracycline
  

Some of these drugs are the same as those used for humans, but others are formulated specifically for dogs. Your veterinarian knows which antibiotics work best for different types of infections and will prescribe the appropriate drug. The vet may also collect a sample of the bacteria and send it to a laboratory for a culture and sensitivity test. This test identifies the bacteria and determines which antibiotic is most effective against it.

Side Effects of Antibiotics for Dogs

Not all antibiotics have the same side effects, though many share similar ones. Fortunately, most antibiotics are generally safe and rarely have serious effects on dogs. If your vet has prescribed antibiotics for your dog, ask about the potential side effects and if there are ways to prevent them.

More serious side effects are called adverse reactions and require veterinary attention. Contact your vet if you notice any problems while giving antibiotics.

Here are some of the most common side effects and adverse reactions of antibiotic use in dogs.

Allergic Reaction

Dogs can have allergic reactions to antibiotics, but it's relatively uncommon. Like humans, dogs can develop allergies to any drug at any time, so past tolerance of a specific antibiotic does not mean it won't cause an allergic reaction in the future.

Signs of allergic reactions range from mild to severe and may occur immediately after taking the antibiotic or hours later. During an allergic reaction, dogs may experience one or more of the following signs:

• Anaphylactic shock
• Swelling of face or muzzle
• Hives or skin rash
• Difficulty breathing
• Seizures
• Excessive drooling
• Vomiting
• Diarrhea

If you notice your dog has trouble breathing or facial swelling, you should bring them to the nearest open veterinary office immediately. Contact the vet's office to let them know you're on the way.

Treatment generally involves injection of steroids and antihistamines to stop the reaction and supportive care as needed (oxygen therapy, fluids, etc.).

If the reaction is mild, meaning your dog is breathing fine but you notice other signs, then you should contact your vet for advice.

Gastrointestinal Upset

Some antibiotics cause nausea, vomiting, diarrhea, and loss of appetite. You'll typically notice these signs within a day or two of starting antibiotics. Giving antibiotics with food can minimize these complications for some dogs. However, if your dog is experiencing GI upset even when the antibiotics are given with food, contact your veterinarian for advice. Your vet may want to switch your dog to a different antibiotic or add another medication to relieve the GI signs.

Microbiome Imbalance

When antibiotics enter the body, they often destroy both beneficial and harmful bacteria. Dogs, like people, have healthy flora in their bodies, especially in the gastrointestinal tract and on the skin. These microbes support the dog's immune system, assist with digestion, and even help produce necessary vitamins and nutrients.

Dogs on antibiotics may suffer GI effects like diarrhea due to gut imbalance. The effects of these imbalances in the body may not appear for weeks after starting antibiotics. To prevent or treat microbiome imbalance, vets often recommend the use of canine probiotic supplements, which are tailored to their specific gut flora. Your vet can recommend the best type of probiotic for your dog's current situation.

Neurological Effects

Some classes of antibiotics carry the risk of causing neurologic effects like ataxia (drunken gait), dilated pupils, head tilt to one side, nystagmus (involuntary rapid eye movement), and even seizures. Metronidazole is a commonly used antibiotic that has been known to have a risk of neurologic effects, but this is uncommon at routinely prescribed doses.

Stop antibiotic use and contact your vet immediately if you notice any neurological abnormalities in your dog.

How to Give Your Dog Antibiotics

If your veterinarian has prescribed antibiotics for your dog, be sure to precisely follow instructions and finish the whole course. If you have concerns about potential side effects call your veterinarian first. Stopping antibiotics early can cause the infection to come back, and the bacteria may become resistant to antibiotic therapy. Instructions for giving antibiotics depend on the form they come in.

Oral Antibiotics

Oral antibiotics may come in the form of pills, tablets, or liquids. Many pet parents have success hiding pills or tablets in food such as peanut butter, cheese, or commercial pill treats designed for this purpose. Liquids can be squirted into the corner of the mouth using an oral syringe. In most cases, it's best to give oral antibiotics with food so they'll be gentler on the stomach.

Topical Antibiotics

Some infections are best treated topically so that the antibiotics come into direct contact with the infection. Certain infections call for both oral and topical antibiotics. Topical antibiotics include:

• Liquid ear solutions for ear infections (you may need to clean the ears first)
• Eye drops for eye infections
• Wipes, sprays, creams, gels, or ointments for skin infections

Injectable Antibiotics

In some cases, injectable antibiotics may be used. Sometimes this option is used for pets that are difficult to medicate at home, as long as it will appropriately treat the infection. Other cases of severe infections may require more aggressive treatment, and your vet may opt to give your dog an antibiotic injection. This will be done in your vet's office and may require hospitalization if multiple injections are required. It's unlikely you'll ever need to give your dog an antibiotic shot at home, but your vet will show you how to do this if it's deemed necessary.

Safety and Warnings

In general, the benefits of antibiotic use in the correct situation outweigh the risks of leaving an infection untreated and are considered safe for dogs when prescribed by a veterinarian. In addition to following your vet's instructions, keep these tips in mind:

• Never give your dog leftover antibiotics from another pet or person unless your vet advises you to do so.
• Keep antibiotics and other medications out of your dog's (and children's) reach.
• Contact your vet if your dog gets an overdose.
• Contact your vet if the antibiotics don't seem to be helping the problem or are causing side effects.
• Always finish the whole course of antibiotics unless your vet says otherwise.

Antibiotic Resistance

Antibiotic resistance is a concern in humans and animals when it comes to their use. It occurs when bacteria become stronger than the antibiotic used to destroy it. The bacteria grows and multiplies, making the infection worse and more difficult to treat. It also creates antibiotic-resistant bacteria in the environment, putting animals and people more at risk with fewer medications able to treat infections.

Vets try to prevent antibiotic resistance by prescribing the most appropriate antibiotic for the bacteria, choosing the right dose, and recommending the proper length of treatment. This is why it is important to finish the prescribed course of antibiotic treatment even if your dog seems better.