A Guide to the Top Antibiotics for Dogs

What you should know about the antibiotics your veterinarian prescribed for your dog.

By
Dr. Jennifer Bailey, DVM
-
Published:
1
A group of pill bottles containing common antibiotics for dogs.
Your veterinarian has dozens of options when prescribing an antibiotic for your dog’s infection and will choose the most appropriate one, based on her professional experience and education. However, it can be helpful if you are aware of any contraindications or potential side effects of your dog’s medication. Credit: Nancy Kerns

Antibiotics are the best weapon in our medical arsenal for fighting bacterial infections in dogs. Prescribed and given appropriately, antibiotics give our dogs the best chance at recovery from an infection. It is important to note that antibiotics are effective only at treating bacterial infections, not canine viral, yeast, or fungal infections.

Some antibiotics are better suited for certain types of infections than others. Your veterinarian will select an antibiotic based on the type of infection your dog has and where that infection is located. The results of a bacterial culture and sensitivity test, when available, can also help direct the antibiotic selection.

Other considerations for antibiotic selection include which formulation is easiest to give your dog (liquid versus tablet), how much your dog weighs, how often the antibiotic needs to be given, what medications your dog is currently being given, and any reactions your dog has had to medications in the past.

You must give antibiotics exactly as prescribed by your veterinarian; there are serious consequences for antibiotic misuse for dogs. Always complete the full course of treatment, even if your dog seems to be feeling better. Contact your veterinarian if your dog experiences one or more side effects from the antibiotic. Your veterinarian may prescribe something to help alleviate the side effect or may prescribe a different antibiotic.

The following is an information guide to the most common antibiotics that are used in dogs.

Amoxicillin for Dogs

Common trade names: Amoxi-Tabs, Amoxi-Drop, Bimox.

Drug class: Penicillin

Indicated for: Respiratory tract infections, urinary tract infections, gastrointestinal infections, skin infections (abscesses, lacerations, and wounds). Can also be used to treat Lyme disease in dogs who are sensitive to or are too young to receive doxycycline.

Contraindications: Should not be used in dogs who have had a previous hypersensitivity to any antibiotic in the penicillin or cephalosporin classes of drugs.

Potential side effects: Diarrhea, vomiting, and loss of appetite.

Formulations available: Tablets, capsules, and oral suspension.

Amoxicillin/Clavulante for Dogs

Common trade names: Clavamox, Augmentin

Drug class: Penicillin

Indicated for: Skin infections (superficial and deep pyoderma), soft tissue infections (wounds, abscesses, cellulitis), periodontal infections, urinary tract infections, endocarditis (heart valve infections), and canine infectious respiratory disease complex caused by a bacterial infection.

Contraindications: Should not be used in dogs who have had a previous hypersensitivity to any antibiotic in the penicillin or cephalosporin classes of drugs.

Potential side effects: Diarrhea, vomiting, loss of appetite.

Formulations available: Tablets and oral suspension. Clavamox is the veterinary formulation and Augmentin is the human formulation. The ratio of amoxicillin to clavulanate is different between Clavamox and Augmentin, so prescribing Clavamox for dogs is preferred over prescribing Augmentin.

Azithromycin for Dogs

Common trade names: Zithromax

Drug class: Macrolide

Indicated for: Skin infections and other susceptible infections. Used to treat susceptible protozoal infections (Babesia gibsoni and microti, theileriosis, and cryptosporidiosis). Also used to treat ileus (cessation of normal gastrointestinal smooth muscle contractions).

Contraindications: Should be used with caution in dogs who have liver disease.

Potential side effects: Diarrhea, vomiting, and loss of appetite.

Formulations available: Tablets, oral suspension. Also available as injection for veterinary use only.

Cephalexin for Dogs

Common trade names: Keflex, Rilexine

Drug class: Cephalosporin

Indicated for: Skin infections, urinary tract infections.

Contraindications: Should not be used in dogs who have had a previous hypersensitivity to any antibiotic in the penicillin or cephalosporin classes of drugs.

Potential side effects: Diarrhea, vomiting, and loss of appetite.

Formulations available: Chewable tablets, capsules, non-chewable tablets, oral suspension.

Cefpodoxime for Dogs

Common trade names: Keflex, Rilexine

Drug class: Cephalosporin

Indicated for: Skin infections, urinary tract infections.

Contraindications: Should not be used in dogs who have had a previous hypersensitivity to any antibiotic in the penicillin or cephalosporin classes of drugs.

Potential side effects: Diarrhea, vomiting, and loss of appetite.

Formulations available: Chewable tablets, capsules, non-chewable tablets, oral suspension.

Cefovecin/Convenia for Dogs

Common trade names: Convenia

Drug class: Cephalosporin

Indicated for: Skin infections. Can be used for (but is not labeled for) urinary tract infections and periodontal infections. Can also be used for (but is not labeled for) treating Lyme disease in canine patients who are sensitive to or are too young to receive doxycycline.

Contraindications: Should not be used in dogs with a previous hypersensitivity to any antibiotic in the penicillin or cephalosporin classes of drugs. Should be used with caution in dogs with kidney disease. The safe use of this drug in puppies younger than 4 months of age has not been established.

Potential side effects: Diarrhea, vomiting, and loss of appetite. This is a long-acting antibiotic. Side effects can remain for up to two months following injection. Anaphylaxis (a severe allergic reaction) has been reported but is rare.

Formulations available: Injection for veterinary use only.

Clindamycin for Dogs

Common trade names: Antirobe, Cleocin.

Drug class: Lincosamide.

Indicated for: Skin infections, dental infections (such as tooth root abscesses), osteomyelitis (bone infections), systemic infections (such as sepsis), surgical prophylaxis (such as before a dental procedure or before a surgical procedure if a dog is hypersensitive to amoxicillin). Also used for susceptible protozoal infections (Babesia gibsoni, Hepatozoon canis, Neospora, and Toxoplasma).

Contraindications: Should be used with caution in dogs who have severe kidney and/or liver disease. Unlike in humans, use of clindamycin in dogs is not associated with an increased risk of severe Clostridium difficile infection and associated diarrhea.

Potential side effects: Diarrhea, vomiting, and loss of appetite. Can cause esophagitis (inflammation of the esophagus) if not given with food or water.

Formulations available: Tablets, capsules, oral solution. Also available as injection for veterinary use only.

Doxycycline for Dogs

Common trade names: Vibramycin, Doxy 100, Doxirobe (periodontal gel).

Drug class: Tetracycline.

Indicated for: Leptospirosis, several tick-borne diseases (anaplasmosis, Lyme disease, erlichiosis, Rocky Mountain spotted fever, babesiosis), and periodontal infections. Also part of the treatment plan for canine heartworm disease.

Contraindications: Do not give with multivitamins, calcium supplements, antacids, or laxatives two hours before or after giving doxycycline; these products may inactivate doxycycline. Should be used with caution in dogs with severe liver disease.

Potential side effects: Vomiting, nausea, and loss of appetite. Can cause esophagitis (inflammation of the esophagus) if not given with food or water. May cause your dog’s skin to become more at risk for developing sunburn, particularly on the nose, eyelids, ears, and underside of the dog’s belly. It’s rare, but it can cause discolored baby teeth in puppies or interfere with the formation of enamel on adult teeth as they are developing in puppies.

Formulations available: Tablets, capsules, oral suspension. Also available as a gel for application under the gums for treatment/prevention of periodontal disease (for veterinary use only).

Erythromycin for Dogs

Common trade names: Gallimycin.

Drug class: Macrolide.

Indicated for: Susceptible infections. Should only be prescribed if a bacterial culture and sensitivity test indicates that this is the best antibiotic to address your dog’s infection. Also used to treat ileus (cessation of normal gastrointestinal smooth muscle contractions).

Contraindications: Should be used with caution in dogs who have the MDR1 (ABCB1) gene mutation. (The breeds that most commonly have this mutation include Collies, Shetland Sheepdogs, Australian Shepherds, Old English Sheepdogs, English Shepherds, German Shepherds, Long-Haired Whippets, Silken Windhounds, and mixed-breed dogs descended from one of those breeds.)

Potential side effects: Diarrhea, vomiting, loss of appetite.

Formulations available: Tablets, capsules, oral suspension. Also available as injection for veterinary use only.

Marbofloxacin/Zeniquin for Dogs

Common trade names: Zeniquin

Drug class: Fluoroquinolone

Indicated for: Skin infections, urinary tract infections, and leishmaniasis.

Contraindications: Do not give at the same time as other medications. Do not give with multivitamins that contain certain minerals, such as calcium, iron, magnesium, aluminum, or zinc. Should be used with caution in dogs who have severe kidney or liver disease. Should be used with caution in dogs who have a seizure disorder. May cause your dog’s skin to become more at risk for developing sunburn, particularly on the nose, eyelids, ears, and underside of the dog’s belly. *  Note: The use of fluoroquinolones is contraindicated for puppies during their rapid growth phase. The rapid growth phase begins at 2 months of age in all puppies and ends at 8 months old for small and medium breed dogs, 1 year of age for large breed dogs, and 18 months old for giant breed dogs. The use of fluoroquinolones in puppies has been shown to cause cartilage deformation within their joints when given for prolonged periods of time at high doses.

Potential side effects: Diarrhea, vomiting, nausea, and loss of appetite.

Formulations available: Tablets.

Metronidazole for Dogs

Common trade names: Flagyl

Indicated for: Severe systemic infections caused by anaerobic bacteria (bacteria that do not require air to grow). May also be used for enteritis (gastrointestinal infections) caused by Clostridium species of bacteria, gastritis (stomach infection) caused by Helicobacter, giardiasis (when used in combination with fenbendazole), hepatic encephalopathy, and canine chronic ulcerative stomatitis.

Contraindications: Should be used with caution in dogs who have severe liver disease.

Potential side effects: Diarrhea, vomiting, nausea, and loss of appetite. Can cause nervous system side effects, including ataxia (wobbly gait) and nystagmus (rapid eye movement).

Formulations available: Tablets, capsules, oral suspension. Also available as injection for veterinary use only.

Orbifloxacin/Orbax for Dogs

Common trade names: Orbax.

Drug class: Fluoroquinolone.

Indicated for: Skin infections, urinary tract infections.

Contraindications: Do not give at the same time as other medications. Do not give with multivitamins that contain certain minerals, such as calcium, iron, magnesium, aluminum, or zinc. Should be used with caution in dogs who have severe liver disease. Should be used with caution in dogs who have a seizure disorder. * Note: The use of fluoroquinolones is contraindicated for puppies during their rapid growth phase. The rapid growth phase begins at 2 months of age in all puppies and ends at 8 months old for small and medium breed dogs, 1 year of age for large breed dogs, and 18 months old for giant breed dogs. The use of fluoroquinolones in puppies has been shown to cause cartilage deformation within their joints when given for prolonged periods of time at high doses.

Potential side effects: Diarrhea, vomiting, nausea, and loss of appetite.

Formulations available: Tablets, oral suspension.

Trimethoprim/Bactrim for Dogs

Common trade names: Bactrim, Sulfatrim, TMS

Indicated for: Skin infections, urinary tract infections, and leishmaniasis. Indicated for treatment of pneumocystis pneumonia caused by Pneumocystis jiroveci. Also used for susceptible protozoal infections (Hepatozoon americanum, Neospora, and Toxoplasma) and for coccidiosis.

Contraindications: Should be used with caution in dogs who have moderate to severe kidney or liver disease. A serious immune-related condition called sulfonamide-induced polysystemic immune complex disease (SPICD) can develop in dogs taking trimethoprim/sulfamethoxazole. Doberman Pinschers, Samoyeds, and Miniature Schnauzers are at increased risk for developing SPICD.

Potential side effects: Keratoconjunctivitis sicca (dry eye).

Formulations available: Tablets, oral suspension.

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