Studies on dogs recently revealed deficiencies in the immune system apparently common to all carnivora.  This is an evolutionary development since meat diets are bacteriocidal. The scientific basis for this contention is described in an article* published in Cell Reports.  Studies conducted at the University of Cambridge, Department of Veterinary Medicine, demonstrated “the lack of functioning genes that contributes to the ability of pathogens to hide undetected in carnivores to potentially mutate and be transmitted, becoming a human health risk.”

The molecular biological studies conducted on a canine cell line demonstrated a “progressive evolutionary down-regulation of pathogen-sensing inflammasome pathways.  These include the loss of nucleotide-oligomerization domain, leucine-rich repeat receptors, and acquisition of a unique caspase-1/-4 effector fusion protein that processes gasdermin D pore formation without inducing rapid lytic cell death and the formation of a caspase-8 containing inflammasome that inefficiently processes interleukin-1 beta.

According to Professor Claire Bryant, in addition to changes in the intestinal tract, the immune deficiency occurs in other organs including the lungs.

This molecular biological explanation confirms the mechanism associated with the high prevalence of SARS-CoV-2 in zoo carnivores including all the large felines and in farmed mink.  Doctor Bryant considers that carnivores held in close proximity in large numbers could create a disease reservoir that would allow pathogens to mutate.  This consideration was evident in Denmark during the early stages of mink COVID and confirms that farming this species will contribute to mutants irrespective of whether or not they are vaccinated.  If the vaccine authorized for animal species is widely deployed, it will be necessary to constantly monitor mink farms and zoos for emerging mutants of SARS-CoV-2, given the compromised immune response inherent to carnivores.

*Digby, Z. et al Evolutionary Loss of Inflammasomes in the Carnivora and Implications for the Carriage of Zoonotic Infections. Cell Reports. doi.org/10.1016.j.cellrep, 2021, 109614.