This is an interesting question! I knew a little bit about Transmissible Spongiform Encephalopathies from being a vet tech (scrapie in sheep & goats, CWD in deer, TME in mink and ferrets, and of course BSE/vCJD in cattle and humans— especially because I lived in Germany and the UK for big chunks of the 80’s and 90’s and so was banned from donating blood until very recently just in case I was a carrier myself!) but because I don’t work in a farm setting it’s not something I really need to keep up with so my knowledge is pretty shallow. This question got me googling and I found this interesting article:

Animals Resistant to Prion Disease: Intrinsic vs. Extrinsic Factors

https://www.frontiersin.org/articles/10.3389/fncel.2020.00254/full#h3

It’s super long and gets very technical at times so I will freely admit that I skimmed big chunks of it, but my “Today I Learned” takeaway is: horses, dogs, and rabbits are very highly resistant to prion disease, as in not developing disease even when injected directly into their brains, let alone when being fed contaminated material. I knew so many different species had their variants (though I also knew not all diseases seem to be able to cross to all species), and that we have evidence of cats and zoo animals becoming ill during the BSE outbreak, so I think in the back of my mind I had an assumption that all mammals would be at risk.

Dogs being resistant makes sense to me— they’re highly generalized scavengers whose whole schtick is being able to thrive on whatever garbage they find lying around, lol. But horses and rabbits are both infamous for being so medically fragile! I guess now I know what superpower they traded away everything else to gain… (/facetious in case that wasn’t clear!)