Early administration of canine parvovirus monoclonal antibody prevented mortality after experimental challenge

Abstract OBJECTIVE To evaluate the effectiveness of canine parvovirus monoclonal antibody (CPMA) as a treatment against canine parvovirus (CPV-2)–induced mortality and to support USDA product licensure. ANIMALS 28 purpose-bred Beagle dogs aged 8 weeks were randomized to the treated (n = 21) or control (7) group. METHODS Dogs were challenged intranasally with 10 4.2 TCID 50 virulent CPV-2b on Day 0 and monitored for 14 days for fecal viral shed and clinical disease. All dogs began shedding CPV-2 on Day 4 and were treated intravenously with a single dose of either CPMA (0.2 mL/kg) or saline (equal volume). No additional treatments were given to either group. Feces and sera were collected for quantitative analysis of fecal viral shed (hemagglutination) and antibody responses (hemagglutination inhibition and dot-blot ELISA), respectively. Dogs were monitored twice daily for parameters including lymphopenia, fever, vomiting, abnormal feces, inappetence, and lethargy. Humane endpoints triggered euthanasia by a veterinarian masked to treatment groups. The primary outcome variable was prevention of mortality as compared to controls. RESULTS Mortality was prevented in all CPMA-treated dogs compared to 57% mortality in the control group ( P = .0017, Fisher exact test). Canine parvovirus monoclonal antibody–treated dogs also experienced less severe and/or shorter durations of diarrhea, fever, vomiting, CPV-2 shedding in feces, and lymphopenia. Both groups showed similar immunoglobulin M responses as measured by semiquantitative analysis. CLINICAL RELEVANCE Intravenous administration of CPMA can effectively improve clinical outcome when administered early in CPV-2 disease. Canine parvovirus monoclonal antibody treatment after proven infection does not interfere with adaptive immunity.