Dogs can take several types of antibiotics, but none should be given without a veterinarian’s guidance. The most commonly prescribed options include amoxicillin-clavulanate, cephalexin, doxycycline, metronidazole, clindamycin, and enrofloxacin. Each one targets different types of bacteria and is chosen based on the specific infection your dog has.
Amoxicillin-Clavulanate for Skin and Dental Infections
Amoxicillin combined with clavulanate (often sold under the brand name Clavamox) is one of the most widely prescribed antibiotics for dogs. The clavulanate component helps the amoxicillin work against bacteria that would otherwise resist it. It’s FDA-approved for skin and soft tissue infections like wounds, abscesses, and cellulitis, as well as periodontal (gum and tooth) infections.
For skin infections, treatment typically lasts 5 to 7 days, or until 48 hours after symptoms clear up. Deeper skin infections can require up to 21 days of treatment, with a maximum of 30 days. If your dog isn’t improving after 5 days, your vet will likely reassess and try a different approach. Plain amoxicillin (without the clavulanate) is also used for certain infections, including Lyme disease, at higher doses given three times daily.
Cephalexin for Pyoderma and Wound Infections
Cephalexin belongs to the cephalosporin class of antibiotics and is a go-to choice for bacterial skin infections in dogs, particularly pyoderma, which shows up as pus-filled bumps, crusty patches, or hair loss. It’s also used for urinary tract infections and wound infections. Cephalexin is typically given two to three times a day, and treatment length depends on how deep the infection goes.
Another cephalosporin, cefpodoxime, is also FDA-approved for treating skin infections in dogs, including wounds and abscesses. A newer option, cefovecin, is given as a single injection by your vet and provides about two weeks of antibiotic activity, which can be helpful for dogs that are difficult to pill at home.
Doxycycline for Tick-Borne Diseases
Doxycycline is a tetracycline antibiotic and the preferred treatment for tick-borne infections like Lyme disease, ehrlichiosis, and anaplasmosis. Vets favor it over other options because dogs with tick-borne illness often carry more than one type of tick-transmitted pathogen at the same time, and doxycycline covers a broader range of those infections than penicillin-type antibiotics do.
Treatment for tick-borne diseases requires a long course, typically four weeks. It’s important to give doxycycline with food because it can irritate the esophagus if swallowed on an empty stomach. Dogs that are difficult to treat orally may be switched to an injectable alternative.
Metronidazole for Diarrhea and GI Issues
Metronidazole (brand name Flagyl) works specifically against anaerobic bacteria, the kind that thrive in low-oxygen environments like the gut. It’s commonly prescribed for diarrhea, inflammatory bowel conditions, and certain parasitic infections. The drug works by entering bacterial cells and breaking apart their DNA, which kills them.
Metronidazole is effective, but it carries a unique risk that other common dog antibiotics don’t: neurotoxicity. If your dog receives too high a dose or stays on it too long, signs can include loss of coordination, involuntary eye twitching, difficulty balancing, or in severe cases, seizures. These effects are typically reversible once the medication is stopped, but they’re a reason vets monitor dosing carefully and generally keep treatment courses short.
Clindamycin for Deep Wounds and Bone Infections
Clindamycin is particularly useful for deep infections that other antibiotics struggle to reach. It’s FDA-approved in dogs for skin infections, deep wounds, abscesses, dental infections, and osteomyelitis (bone infections). It penetrates well into bone tissue, which makes it one of the few oral antibiotics effective for skeletal infections.
Clindamycin also works well against anaerobic bacteria, the types commonly found in bite wounds, abscesses, and dental disease. It’s often chosen when a dog’s infection involves a mix of bacteria living in oxygen-poor tissue deep below the skin surface.
Enrofloxacin and Why It’s Reserved for Tough Cases
Enrofloxacin is a fluoroquinolone, a powerful class of antibiotic that vets typically reserve for infections that haven’t responded to safer first-line options. It’s used for urinary tract infections, respiratory infections, and skin infections caused by resistant bacteria.
The main safety concern is joint damage. In young, growing dogs, enrofloxacin can damage the cartilage in joints and cause lameness. For this reason, it’s generally avoided in puppies and large-breed dogs that are still growing. Even in adult dogs, fluoroquinolones are considered a “last resort” class because overuse contributes to antibiotic resistance.
Common Side Effects Across All Antibiotics
The most frequent side effects you’ll see with nearly any antibiotic are gastrointestinal: vomiting, diarrhea, loss of appetite, or softer stools than usual. This happens because antibiotics don’t just kill the harmful bacteria causing the infection. They also disrupt the beneficial bacteria living in your dog’s gut, reducing the diversity and balance of the microbiome. This disruption can lead to blooms of harmful organisms that were previously kept in check by the healthy gut bacteria.
Giving antibiotics with food often reduces stomach upset. Some vets recommend probiotics during or after a course of antibiotics to help restore gut bacteria, though the timing and specific product matter. If your dog develops severe diarrhea, bloody stool, or stops eating entirely during antibiotic treatment, contact your vet rather than simply stopping the medication, since ending a course early can allow resistant bacteria to survive and make the infection harder to treat the second time around.
Why Human Antibiotics Aren’t Interchangeable
Some antibiotics prescribed for dogs, like amoxicillin, cephalexin, and doxycycline, are the same molecules used in human medicine. But the dosages, formulations, and treatment durations are different. A dog’s metabolism processes drugs at a different rate than yours, and the wrong dose can be ineffective or toxic. Human combination products also sometimes contain additional ingredients, like xylitol in liquid formulations, that are safe for people but poisonous to dogs.
Giving your dog leftover human antibiotics, or antibiotics prescribed for a different pet, risks undertreating the actual infection, causing unnecessary side effects, and breeding antibiotic-resistant bacteria. The specific antibiotic your vet chooses depends on where the infection is, what type of bacteria is likely causing it, and sometimes the results of a culture test that identifies exactly which drugs will work.