The mouse, civits etc. sicken, or die, or are sacrified (killed) and found to have infected lungs.
I can't find my cat links but I recall there are studies with cats which all developed antibodies as hoped, and then when exposed to the virus, died.
I think it was Moderna that had a laughably small animal trial using a species of primate that never becomes severely ill with Covid. I read a research review recently saying that Pfizer and Moderna skipped animal trials - I see this kind of statement when they mean that the effort was too paltry and lacking in rigor to count as a normal animal trial.
Below I'll quote a great article by Christian Elliot that all who need to educate their employers and family members or physicians may want to share:
18 Reasons I Won't Be Getting a Covid Vaccine (deconstructingconventional.com)
"After 2000, scientists made many attempts to create coronavirus vaccines.
For the past 20 years, all ended in failure because the animals in the clinical trials got very sick and many died, just like the children in the 1960's.
You can read a summary of this history/science here.
Or if you want to read the individual studies you can check out these links:
In 2004 attempted vaccine produced hepatitis in ferrets
In 2005 mice and civets became sick and more susceptible to coronaviruses after being vaccinated
In 2012 the ferrets became sick and died. And in this study mice and ferrets developed lung disease.
In 2016 this study also produce lung disease in mice.
The typical pattern in the studies mentioned above is that the children and the animals produced beautiful antibody responses after being vaccinated.
The manufacturers thought they hit the jackpot.
The problem came when the children and animals were exposed to the wild version of the virus.
When that happened, an unexplained phenomenon called Antibody Dependent Enhancement (ADE) also known as Vaccine Enhanced Disease (VED) occurred where the immune system produced a "cytokine storm" (i.e. overwhelmingly attacked the body), and the children/animals died.
Here's the lingering issue...
The vaccine makers have no data to suggest their rushed vaccines have overcome that problem.
In other words, never before has any attempt to make a coronavirus vaccine been successful, nor has the gene-therapy technology that is mRNA "vaccines" been safely brought to market, but hey, since they had billions of dollars in government funding, I'm sure they figured that out.
Except they don't know if they have...
Bkmk