Testing of Select Wild Mustelids for SARS-CoV-2

Since the beginning of the COVID-19 pandemic, there has been concern about what animal species might be at risk of infection with SARS-CoV-2. A number of studies have been performed to determine the susceptibility of both domesticated and wild species, and there are a number of animals that appear to be susceptible to infection and disease; however, one group that seems to be especially susceptible to this virus are the mustelids. This was shown most dramatically in April 2020 when SARS-CoV-2 outbreaks on mink farms in the Netherlands began to occur (Oreshkova 2020). Over the next year, mink farms in multiple countries, including 2 farms in British Columbia in December 2020 (BC Gov News 2020), have reported outbreaks in the mink in their facilities. These outbreaks are not only a concern for the mink on the farm and the human workers, but there is also a concern for wildlife in the local area. Unfortunately, these concerns were confirmed in December 2020 when a free-ranging wild mink captured near a mink farm in Utah was found to be positive for SARS-CoV-2 (DeLiberto and Shriner 2020). Since that time, there has been an additional report of two wild mink in Spain infected with SARS-CoV-2 (Aguilo-Gisbert et al. 2021).

“American Mink, Centre Island, Toronto, ON” by tsaiproject is licensed under CC BY 2.0

The news of the first free-ranging wild animal testing positive for SARS-CoV-2 was a huge concern for all of us who work with wildlife on a daily basis. At CWHC ON/NU we have worked with the Animal Health Laboratory here in Guelph and have instituted specific safety protocols to work with any wild mustelid that we bring into our facility. Luckily for us, we haven’t had many suspect cases, but we have tested two mustelids for SARS-CoV-2 to date (under the approval of the Chief Veterinarian for Ontario).

“Ermine: Bacon Fiend” by Kurayba is licensed under CC BY-SA 2.0

The first mustelid tested was an ermine that was captured in Burlington and brought to a local wildlife rehabilitator. The ermine was found to have signs of respiratory illness, which was concerning for underlying pneumonia. As SARS-CoV-2 will cause pneumonia in mustelids, the rehabilitation centre followed strict protocols to minimize the risk to anyone handling the ermine. Swabs and inactivating media (a solution that inactivates any virus present, so it is no longer infectious) were shipped to the rehabilitator to collect samples for testing of this ermine. The ermine unfortunately was not responding to treatment and its condition was worsening, so it was euthanized after a few days in care. The rehabilitator swabbed the ermine and placed the swabs in the inactivating media for the appropriate time before sending the samples back to Guelph for testing. The ermine tested negative for SARS-CoV-2 by PCR and at that point, the body was able to be sent to CWHC ON/NU for post-mortem examination. The post-mortem findings indicated that this ermine had pneumonia, which was most likely secondary to a bacterial infection.

The second case was a mink that was unfortunately killed by a domestic dog. This mink was found in a local hotspot for human COVID-19 infections (Mississauga). SARS-CoV-2 testing was requested for this mink for surveillance purposes based on its location in a SARS-CoV-2 hotspot. The mink was brought to our facility where appropriate precautions were taken to minimize the chances of exposure to anyone coming in contact with this mink. Post-mortem findings in this case indicated that the mink had died secondary to trauma (consistent with the history of a dog attack) and there was no evidence of underlying disease. Swabs from this mink were found to be negative for SARS-CoV-2. Additionally, this mink was tested for rabies virus and was also found to be negative.

These two cases help to highlight how we at CWHC ON/NU are continually working with our partners to respond to emerging infectious diseases that could negatively impact our free-ranging wildlife, domestic animals, and humans. 

For links to additional information on COVID-19 and wildlife, including our Interim guidance for Wildlife health and SARS-CoV-2 in Canada: Bats, please visit:  http://www.cwhc-rcsf.ca/covid-19.php.


Aguilo-Gisbert J, Padilla-Blanco M, Lizana V, Maiques E, Munoz M, Chillida-Martinez E, Cardells J, Rubio-Guerri C. First description of natural SARS-CoV-2 infection in two wild American minks (Neovison vison). Preprints. 25 March 2021. (doi: https://doi.org/10.20944/preprints202103.0647.v1)

BC Gov News. Mink on second farm test positive for COVID-19. December 2020. https://news.gov.bc.ca/releases/2020AFF0067-002145

DeLiberto T and Shriner S. Coronavirus Disease 2019 Update (536): Animal, USA (Utah) Wild Mink, First Case. ProMED International Society for Infectious Disease. December 2020. https://promedmail.org/promed-post/?id=8015608

Oreshkova N, Molenaar RJ, Vreman S, Harders F, Munnick BBO, Hakze-van der Honing RW, Gerhards N, Tolsma P, Bouwstra R, Sikkema RS, Racken MGJ, de Rooij MMT, Weesendorp E, Engelsma MY, Bruschke CJM, Smit LAM, Koopmans M, van der Poel WHM, Stegeman A. SARS-CoV-2 infection in farmed minks, the Netherlands, April and May 2020. Euro Surveill. 25(23), 2020.doi: 10.2807/1560-7917.ES.2020.25.23.2001005

Submitted by: Brian Stevens – CWHC ON/NU

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