SARS-CoV-2 in cats, dogs, ferrets, and minks: The ACE2 receptor connection

In a recent review¹ published in the journal Viruses, researchers discussed the potential risks of animal-to-human and human-to-animal transmission of SARS-CoV-2—the virus causing COVID-19 in humans. The researchers focused on cats, dogs, ferrets, and farm minks.

SARS-CoV-2 uses the ACE2 receptor for the virus to enter its host. Twenty-four amino acid residues in human ACE2 are required to bind to SARS-CoV-2’s spike protein. A species with similar amino acid residues would be a susceptible host. Dogs’ and cats’ ACE2 has greater than 50% similarity to human ACE2.¹

Cats are more sensitive to SARS-CoV-2 than dogs. Since the start of the pandemic, there have been 126 outbreaks of SARS-CoV-2 reported in cats (67 in the United States)¹ and only a few cases in dogs. These animals likely contracted COVID-19 from their infected owners, and subsequently developed respiratory symptoms. Of serum samples collected from cats, 14.7% contained SARS-CoV-2, and of those 10.8% contained viral neutralizing antibodies.¹ Only 3.3% of 919 dogs had SARS-CoV-2 neutralizing antibody titers.¹ The data shows that it is possible, but not likely, for dogs and cats to acquire COVID from their owners.

Ferrets are highly susceptible to SARS-CoV-2 both naturally and experimentally. SARS-CoV-2 antibodies remained at detectable levels for more than 129 days after the first detection of antibodies.¹ Researchers tested lopinavir-ritonavir, hydroxychloroquine sulfate, and emtricitabine-tenofovir as antivirals for COVID in ferrets. Only emtricitabine-tenofovir lowered the virus titers in ferrets.¹ Lipoprotein fusion inhibitors were also used in ferrets to completely block transmission.

Farmed minks have also contracted SARS-CoV-2 and are very susceptible. One case of a mink likely transmitting COVID to a human has been reported,¹ and in that case, the mink and human were in close contact.

Overall, we should be cautious about infecting pets, cats particularly. Ferrets are a good animal model that is being used to study SARS-CoV-2, and minks are the one animal that has been shown to have the potential to infect humans, but more research is needed.

Ryan Moriarty is a 2022 PharmD candidate at the University of Connecticut.

Reference

1. Dróżdż M, Krzyżek P, Dudek B, Makuch S, Janczura A, Paluch E. Current state of knowledge about role of pets in zoonotic transmission of SARS-CoV-2. Viruses. 2021;13(6):1149. Published June 16, 2021. doi:10.3390/v13061149