Dr. Jerusha (Jessie) Lay, Assistant Professor of Animal Health
Coronaviruses are a family of related viruses, and just like any other family, they have some things in common and some differences.
Many types of coronaviruses have been around for years. SARS-CoV-2 is the specific virus causing the disease COVID-19 and the current worldwide pandemic. Coronaviruses are strands of RNA. Once a virus is inhaled or makes its way into the airways, it begins to replicate. As a virus multiplies, it may mutate, which means that the copy is different than the original. Small changes in the strand of RNA can result in big differences in what the virus does to those it infects. For example, cats that are infected with a common type of cat coronavirus usually show mild symptoms or no symptoms at all. The cat's immune system will be exposed to the virus, then it will develop immunity. Rarely, in kittens, the virus may mutate and cause a fatal infection of the abdominal cavity.
Most of these viruses cannot cross species barriers, which means that a coronavirus of cows will only infect cows, the coronavirus of dogs will only infect dogs, and so on. These viruses may cause different symptoms, depending on the virus and animal. The coronavirus of cattle may cause diarrhea and/or respiratory disease, which is often severe in calves. The coronavirus in dogs also causes diarrhea and is often included in the distemper-parvo vaccine for puppies. A common version of a coronavirus that is self-limiting has been in humans for a long time but did not cause the severe disease like this current strain we are seeing and had not been found to be transmitted into animals.