Prolonged Antibody Responses in Dogs and Cats Exposed to COVID-19 Diagnosed Pet Owners

Abstract:

Background: Dogs and cats can be infected with SARS-CoV-2 and develop various clinical presentations. Active surveillance of potentially zoonotic pathogens in pets is required as part of the One Health initiative’s aim to study interaction of pathogens between people, animals, and the environment.

Objectives: To investigate immunoglobulin responses after dog and cat short- and long-term exposure to COVID-19 diagnosed pet owners.

Animals: A total of 1,000 serum samples from dogs (n =747) and cats (n=253) owned by 1, 299 surveyed pet-owners in the United States were evaluated.

Methods: Serum samples were analyzed using recombinant nucleo-capsid and spike proteins using enzyme linked immunosorbent assay (ELISA) tests for IgM and IgG antibodies. Time between exposure and antibody testing was collected from unique pet-owner reported survey information for individual dogs and cats. The proportion of antibody responses were compared using generalized mixed effects logistic regression (GLMER).

Results: Immunoglobulin responses were more frequently directed against spike than nucleo-capsid proteins in dogs and cats (Table). IgG responses were more frequent than IgM responses in both species. The longest time interval between reported COVID-19 exposure and immunoglobulin detection was 840 days in dogs, and 660 days in cats. IgG and IgM had similarly long intervals between exposure and immunoglobulin testing in dogs, but not in cats.

Conclusions: Protracted IgG and IgM responses in US dogs suggest repeated exposure to SARS-CoV-2. Differences in husbandry practices, or species-specific immune systems between dogs and cats may explain the different immunoglobulin responses in our study.