Evidence of exposure to SARS-CoV-2 in cats and dogs from households in Italy

  1. E.I. Patterson
  2. G. Elia
  3. A. Grassi
  4. A. Giordano
  5. C. Desario
  6. M. Medardo
  7. S.L. Smith
  8. E.R. Anderson
  9. T. Prince
  10. G.T. Patterson
  11. E. Lorusso
  12. M.S. Lucente
  13. G. Lanave
  14. S. Lauzi
  15. U. Bonfanti
  16. A. Stranieri
  17. V. Martella
  18. F. Solari Basano
  19. V.R. Barrs
  20. A.D. Radford
  21. U. Agrimi
  22. G. L. Hughes
  23. S. Paltrinieri
  24. N. Decaro

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Abstract

SARS-CoV-2 originated in animals and is now easily transmitted between people. Sporadic detection of natural cases in animals alongside successful experimental infections of pets, such as cats, ferrets and dogs, raises questions about the susceptibility of animals under natural conditions of pet ownership. Here we report a large-scale study to assess SARS-CoV-2 infection in 817 companion animals living in northern Italy, sampled at a time of frequent human infection. No animals tested PCR positive. However, 3.4% of dogs and 3.9% of cats had measurable SARS-CoV-2 neutralizing antibody titers, with dogs from COVID-19 positive households being significantly more likely to test positive than those from COVID-19 negative households. Understanding risk factors associated with this and their potential to infect other species requires urgent investigation.

One Sentence Summary

SARS-CoV-2 antibodies in pets from Italy.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2020.07.21.214346: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementIRB: Sampling of animals for this study was approved by the Ethics Committee of the Department of Veterinary Medicine, University of Bari, Italy (approval number 15/2020).
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variableData analysis: Fisher’s exact test was used to analyze differences in antibody detection from households with known COVID-19 infection status, and antibody detection from male and female animals.
    Cell Line Authenticationnot detected.

    Table 2: Resources

    Experimental Models: Cell Lines
    SentencesResources
    The virus-serum dilution was inoculated onto Vero E6 cells, incubated at 37°C for 1 hour, and overlaid as in standard plaque assays.
    Vero E6
    suggested: None
    Software and Algorithms
    SentencesResources
    All statistical analyses were performed in GraphPad Prism.
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. NCRC

    Our take

    A study, available as a preprint and thus not yet peer reviewed, of 540 dogs and 277 cats in northern Italy showed no evidence of current SARS-CoV-2 infection, but >3% of animals had antibodies suggesting that in areas with active transmission among humans, pets may be occasionally exposed to the virus. Although there is little evidence that dogs or cats develop serious symptoms following exposure or transmit the virus to other animals or humans, household pets should be isolated from owners with COVID-19 to prevent transmission.

    Study design

    ecological

    Study population and setting

    The focal population included 817 pets (540 dogs, 277 cats) in northern Italy surveyed from March to May 2020. Samples mainly came from the region of Lombardy (476 dogs, 187 cats). Oropharyngeal, nasal, and rectal swabs were collected by their regular veterinarian during routine visits. Pets were from households with and without COVID-19 cases. A subset of animals (340 dogs, 188 cats) had full clinical histories available, including breed, sex, age, exposure to COVID-19 cases, and presence of respiratory symptoms. Another subset of animals had serum samples available to test for SARS-CoV-2 antibodies: 188 dogs and 63 cats with full histories and 200 dogs and 89 without historical information.

    Summary of main findings

    None of the 839 swab samples from 817 animals tested positive for SARS-CoV-2 based on a PCR test targeting the nucleoprotein and envelope protein genes; this includes 38 dogs and 38 cats with respiratory symptoms at the time of sampling, and 64 dogs and 57 cats that were living in homes with confirmed COVID-19 cases. Serological testing showed that 13/388 dogs (3.4%) and 6/152 cats (3.9%) had neutralizing antibodies to SARS-CoV-2. Dogs from households with COVID-19 cases and male dogs were significantly more likely to be seropositive. There was also a borderline positive (p = 0.051) rank correlation between the seropositivity of dogs and the human COVID-19 case density (cases per 10,000 people) in provinces with at least ten samples. Similar trends were observed in cats, but statistical tests were not significant.

    Study strengths

    The study included a much larger sample size of cats than a previous serological survey in China, and was the first large survey of SARS-CoV-2 infection and serology in dogs. Animals came from a range of age groups and varied in their exposure to human COVID-19 cases, unlike other reports that tested animals from COVID-19 case households only.

    Limitations

    It is unclear where and when many animals were exposed to SARS-CoV-2, since some were not from households with COVID-19 cases. The small sample size meant that the study was not powered to detect differences in prevalence between animals from COVID-19 case households and non-case households or differences between male and female cats. The correlation between animal seropositivity and human COVID-19 case density across provinces should be regarded with caution because of the very limited number of provinces with sufficient data (n = 4 for cats, n = 6 for dogs).

    Value added

    This study adds to evidence in China and the United States that dogs and cats produce antibody responses following exposure to SARS-CoV-2 from their owners or within the community. However, research has yet to provide evidence that pets with SARS-CoV-2 infection can transmit the virus back to humans. Additionally, studies have not provided evidence of transmission between cats or dogs outside of the laboratory.

  3. ScreenIT

    SciScore for 10.1101/2020.04.07.029090: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • No conflict of interest statement was detected. If there are no conflicts, we encourage authors to explicit state so.
    • No funding statement was detected.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  4. Version published to 10.1101/2020.07.21.214346v2 on bioRxiv
  5. Version published to 10.1101/2020.07.21.214346v1 on bioRxiv