Antibiotic doses for dogs vary widely depending on the specific drug, your dog’s weight, and the type of infection being treated. There is no single “antibiotic dose” for dogs. A dose that works for one antibiotic could be dangerously wrong for another. Veterinarians calculate every prescription individually, and getting the dose right matters for both effectiveness and safety.
How Veterinarians Calculate the Dose
Every antibiotic has a recommended dose expressed in milligrams per kilogram (or per pound) of your dog’s body weight. To get the actual amount your dog needs, you multiply that rate by your dog’s weight. For example, if an antibiotic is dosed at 10 mg per kilogram and your dog weighs 20 kg (about 44 pounds), the dose would be 200 mg per administration.
This calculation changes for every antibiotic. Amoxicillin is typically prescribed at 10 mg per kilogram of body weight, given twice daily. Cephalexin, commonly used for skin infections, is dosed at 15 to 30 mg per kilogram twice daily. Amoxicillin-clavulanate (sold as Clavamox) runs about 6.25 mg per pound of body weight twice daily. These differences are significant: giving a cephalexin-sized dose of a more concentrated antibiotic could cause serious harm.
Common Antibiotics and Their Typical Doses
Here are the standard veterinary dosing ranges for the antibiotics most frequently prescribed to dogs:
- Amoxicillin: 10 mg/kg twice daily, for a minimum of 5 consecutive days
- Amoxicillin-clavulanate (Clavamox): 6.25 mg/lb twice daily
- Cephalexin: 15 to 30 mg/kg twice daily (or 30 to 60 mg/kg once daily for skin infections)
- Clindamycin: 2.5 to 15 mg/lb every 12 hours for wound, abscess, and dental infections; 5 to 15 mg/lb every 12 hours for bone infections
- Metronidazole: 10 to 15 mg/kg twice daily for 7 days (commonly used for diarrhea and gastrointestinal infections)
- Doxycycline: 10 mg/kg once daily for 30 days (standard treatment for tick-borne diseases like Lyme disease)
Notice the range even within a single drug. Clindamycin can be prescribed anywhere from 2.5 to 15 mg per pound depending on the severity and location of the infection. Your vet picks the right point in that range based on what’s going on with your specific dog.
Why “Twice Daily” Isn’t Always the Rule
Most canine antibiotics are given twice daily, meaning every 12 hours. But some are effective at once-daily dosing. Doxycycline for tick-borne illness is given once a day. Cephalexin can be given once daily at a higher dose (30 to 60 mg/kg) instead of twice daily at a lower dose, and research shows both schedules work equally well for skin infections.
Spacing matters. “Twice daily” means roughly 12 hours apart, not just two doses at some point during the day. If you give both doses within a few hours of each other, blood levels of the drug spike and then drop too low before the next dose, reducing effectiveness and potentially encouraging resistant bacteria.
How Long the Course Should Last
Treatment duration depends entirely on the condition. A straightforward skin or wound infection might need 7 to 14 days of antibiotics. Lyme disease treatment with doxycycline typically runs a full 30 days. Deep infections like bone infections can require weeks or even months of treatment.
The American Animal Hospital Association’s antimicrobial stewardship guidelines emphasize that duration should be based on scientific evidence for each specific condition, not a one-size-fits-all rule. Your vet may also schedule a recheck partway through treatment to decide whether to continue, adjust, or stop the medication. Finishing the full prescribed course as directed helps prevent the infection from bouncing back and reduces the risk of breeding antibiotic-resistant bacteria.
Why Human Antibiotics Are Risky for Dogs
Even when the active ingredient is the same, human antibiotics can be dangerous for dogs. Human formulations often contain inactive ingredients, colors, or preservatives that are safe for people but toxic to dogs. Some liquid amoxicillin products made for children contain xylitol, an artificial sweetener that can cause life-threatening drops in blood sugar and liver failure in dogs. The dose in a human product is also calibrated for human body weights and conditions, making it easy to accidentally underdose or overdose your dog.
Veterinary-specific formulations are made with dogs in mind, using safe inactive ingredients and tablet sizes that allow for accurate weight-based dosing.
Signs of Antibiotic Overdose
If your dog gets too much of an antibiotic, symptoms can range from mild stomach upset to serious neurological problems. The most common signs of overdose include drooling, loss of appetite, vomiting, and diarrhea. More serious cases can cause tremors, seizures, excessive drinking or urinating, and skin lesions.
Some antibiotics carry specific risks at high doses. Enrofloxacin, a fluoroquinolone antibiotic, is contraindicated in small and medium breed puppies during rapid growth (roughly 2 to 8 months of age) because it can damage developing cartilage and cause joint problems. Large and giant breeds remain in this vulnerable growth phase even longer, up to 12 or 18 months. In adult dogs, enrofloxacin at the standard dose of 5 mg/kg daily showed no joint problems in clinical trials, but doses of 50 mg/kg daily caused vomiting and appetite loss, and 125 mg/kg daily caused depression, difficulty walking, and death.
Those numbers illustrate why precision matters. The margin between a therapeutic dose and a toxic dose varies by drug, and with some antibiotics, it’s narrower than you might expect.
Getting the Dose Right at Home
Once your vet prescribes an antibiotic, the most important things you can do are weigh your dog accurately, give the exact amount prescribed, maintain consistent timing between doses, and complete the full course. If your dog vomits within 30 minutes of a dose, contact your vet about whether to re-dose. If you miss a dose, give it as soon as you remember, but if it’s nearly time for the next one, skip the missed dose rather than doubling up.
Liquid formulations often need refrigeration and have a short shelf life once mixed, so check the label. Tablets can sometimes be hidden in food, but confirm with your vet that the specific antibiotic can be given with meals, since some drugs absorb differently with food in the stomach.