Canine Parvovirus infection is a disease caused by Canine Parvovirus (CPV) that results in hemorrhagic gastroenteritis and secondary infections, mainly in puppies between six weeks and six months old that are not immunized. Since there is no specific treatment for the condition, supportive therapy based on antibiotics, antiemetics, and non-steroidal anti-inflammatory drugs is traditionally used. Ozone therapy is an economical treatment that has bactericidal, fungicidal, and antiviral properties, besides promoting oxygenation and tissue regeneration, as well as anti-inflammatory and analgesic effects, and was used as a complementary therapy in this study. Therefore, four mixed-breed dogs, aged between 2 and 3 months, with no previous immunization against CPV and testing positive for the virus in a rapid test were selected. The animals were randomly distributed into two groups, being 1: the control group (n=2) that received only supportive treatment; and 2: the experimental group (n=2), that in addition to conventional therapy received intravenously 500 mL of ozonized Ringer's Lactate solution. Before treatment and after 24 and 48 hours, the following clinical signs were evaluated: episodes of emesis and diarrhea, weight, hydration, blood glucose level, abdominal pain, and blood count. One control group animal died within the first hours of hospitalization. Both animals in the experimental group presented faster resolution of diarrheal episodes and shorter hospitalization time when compared to the surviving animal that received only supportive treatment. Although further studies are needed, ozone therapy showed promising results for the treatment of canine parvovirus.