Parvoviruses are the smallest non-enveloped DNA viruses. Their capsid has approximately a diameter of 18 to 22nm. They are very resistant to environmental influences and are able to survive for several months in the outside world. They can be transferred indirectly via shoes and clothing and thus also infect animals only kept inside. The canine parvovirus (CPV) has been mutated in the mid-70s from the feline parvovirus (FPV).
The FPV and CPV are very similar and their DNA matches to 99%. The differences are a few nucleotide sequences in the protein structure responsible for the different biological characteristics. Meanwhile the virus types CPV-2a and CPV-2b are dominating. They have expanded their host range and can infect both dogs and cats, leading to diseases and are transmitted between them.
Coronaviruses are nonenveloped RNA viruses. They are not very species-specific. Thus the canine coronavirus (CCV) is closely related with the feline coronavirus (FCoV) and also infectious for cats. CCV can cause enteritis in cats, but not a feline infectious peritonitis (FIP).
However, recent studies have shown that some isolates of the feline infectious peritonitis virus are recombinants from the canine corona virus and feline coronavirus. For long, coronaviruses are not stable in the environment.
Nevertheless, FCoV may remain infectious dried on surfaces, e.g. in the household, on feeding bowls for dogs and cats or on cat litter boxes, and thus be transferred indirectly.