[header] How to treat feline panleukopenia (distemper ) [title] Keep an eye out for a high fever. [step] The incubation period from being in contact with the virus to developing clinical signs is approximately four to five days. The first symptom to develop is a high fever, which can occur so suddenly that the owner suspects their cat has been poisoned. 
[substeps] In adult cats that have a strong immune system or are vaccinated, they may contact the virus but keep it in check and not become ill. [title] Watch for vomiting and bloody diarrhea to start.