Canine parvovirus monoclonal antibody successfully prevented disease when administered before canine parvovirus experimental challenge

Objective: To determine the effectiveness of canine parvovirus (CPV-2) monoclonal antibody (CPMA) to prevent CPV-2 disease after an experimental challenge to support a label claim for prophylactic use. Methods: 25 Beagle pups aged 7 to 8 weeks were randomized to CPMA-treated (n = 20) or PBS-treated control (5) groups. One day after SC administration of PBS or CPMA (0.1 mL/kg) on study day (SD) 0, all pups were challenged by intranasal administration of virulent CPV-2b. Personnel masked to treatment groups monitored clinical signs, including rectal temperature, vomiting, and/or abnormal feces, over SD 2 through SD 14. Samples collected included sera, whole blood, and feces to assess antibody responses, lymphopenia, and fecal shedding of CPV-2, respectively. The CPV-2 disease case definition included at least 3 of 4 criteria: fever of 39.7 °C (103.4 °F) or greater, decreased lymphocytes to 50% of baseline or below, presence of diarrhea, and detection of CPV-2 virus in feces. Results: All 5 control pups developed parvovirosis and met the CPV-2 case definition. In contrast, none of the 19 CPMA prophylactically treated pups developed more than 1 of the criteria for CPV-2 disease. One pup infected with CPV-2 via environmental exposure and treated therapeutically was also protected against CPV-2 disease signs. Conclusions: Prophylactic CPMA treatment successfully protected all pups from experimental CPV-2 disease. Clinical Relevance: Prophylactically administered CPMA provides a reasonable expectation of passive protection of naïve pups against parvovirosis in high-risk settings, such as outbreak situations.