Abstract
Animals like mink, cats and dogs are susceptible to SARS-CoV-2
infection. In the Netherlands, 69 out of 127 mink farms were infected
with SARS-CoV-2 between April and November 2020 and all mink on infected
farms were culled after SARS-CoV-2 infection to prevent further spread
of the virus. On some farms, (feral) cats and dogs were present. This
study provides insight into the prevalence of SARS-CoV-2 positive cats
and dogs in ten infected mink farms and their possible role in
transmission of the virus. Throat and rectal swabs of 101 cats (12
domestic and 89 feral cats) and 13 dogs of ten farms were tested for
SARS-CoV-2 using PCR. Serological assays were performed on serum samples
from 62 adult cats and all 13 dogs. Whole Genome Sequencing was
performed on one cat sample. Cat-to-mink transmission parameters were
estimated using data from all ten farms. This study shows evidence of
SARS-CoV-2 infection in twelve feral cats and two dogs. Eleven cats
(19%) and two dogs (15%) tested serologically positive. Three feral
cats (3%) and one dog (8%) tested PCR-positive. The sequence generated
from the cat throat swab clustered with mink sequences from the same
farm. The calculated rate of mink-to-cat transmission showed that cats
on average had a chance of 12% (95%CI 10% to 18%) of becoming
infected by mink, assuming no cat-to-cat transmission. As only feral
cats were infected it is most likely that infections in cats were
initiated by mink, not by humans. Whether both dogs were infected by
mink or humans remains inconclusive. This study presents one of the
first reports of interspecies transmission of SARS-CoV-2 that does not
involve humans, namely mink-to-cat transmission, which should also be
considered as a potential risk for spread of SARS-CoV-2.