Here's a link to an article on the first animal trails for the SARS-Cov-1 mRNA vaccine.

All the ferrets died after being vaccinated then exposed to a corona virus.

All the cats too.

When they sacrificed the unvaccinated animals their immune system had a great response. The vaccinated animals had their immune systems go into overdrive and kill the animals.

It's a bit complicated but basically when exposed to a corona virus their immune system turned on but couldn't turn off once it had the virus under control.

This is why they skipped the animal trails this time around.

http://www.thepeoplesvoice.org/TPV3/Voices.php/2021/02/20/covid-19-mrna-injections-the

There's also a compelling argument around leaky vaccines and mareks virus in chickens. Again it's complicated but essentially the vaccinated chickens become hosts for the virus to mutate and grow stronger which in turn has devastating effects on the unvaccinated chickens. Before the vaccine Marek's was a nuisance, now it's devestating costing billions a year in lost product.