Amoxicillin is an antibiotic in the penicillin family. If a dog is allergic to penicillin, oxacillin, nafcillin or any other penicillin-based antibiotics, the dog will also be allergic to amoxicillin. Amoxicillin can be found in combination with other brand name drugs, such as Clavamox and Augmentin, which are a combination of amoxicillin and clavulanate potassium.
According to "The Pill Book Guide to Medication for Your Dog and Cat" (Kate A.W. Roby, VMD, et al, 1998), the usual dosage is given twice a day. The ratio is 5 to 10 milligrams per pound or 10 to 25 milligrams per kilogram. Amoxicillin is best given around mealtime to avoid any digestive problems.
Depending on how bad the dog's infection is, a vet might choose to give a dosage three times a day instead of just twice. A vet needs to determine if the dog needs the low end of the scale or the high. Amoxicillin is generally thought to be safe in puppies and senior dogs but is not for pregnant or nursing dogs because amoxicillin can cause defects in the smallest puppies.
The normal side effect for amoxicillin is a brief bout of diarrhea. This can be countered by feeding your dog a teaspoon of plain yogurt with live cultures every day. If the dog is more than 50 pounds, then a tablespoon of yogurt can be given. Other side effects need to be reported to the vet immediately, because they could signal an allergy. These include vomiting, breathing problems, strange swellings on the face or body, fever and bleeding from the anus or nose.
Amoxicillin comes in tablet, liquid and injectable forms. "The Pill Book Guide to Medication for Your Dog and Cat" recommends using the injectable form for animals that are extremely sick or have poor powers of digestion. Liquid forms need to be shaken before being given.Tablets come in sizes ranging from 50 to 400 milligrams.
Like all antibiotics, amoxicillin needs to be given for seven to 10 days for it to be able to kill off any harmful bacteria. Stopping amoxicillin before that time frame can cause the bacteria to come back. If any liquid amoxicillin in an opened bottle is not used in 14 days, it needs to be tossed out.