Which disease is caused by a viral infection in cats that is highly fatal?

Feline panleukopenia is a highly contagious and fatal viral disease caused by the feline parvovirus. It primarily affects rapidly dividing cells in the body, which leads to a significant drop in white blood cell counts, hence the term "panleukopenia," meaning a reduction in white blood cells. This condition makes cats highly susceptible to secondary infections, leading to severe complications and often resulting in death.

The disease can manifest with symptoms such as vomiting, diarrhea, severe lethargy, and dehydration, and it is particularly dangerous for kittens who may not have fully developed immune systems. Vaccination is key in preventing this disease, and it is recommended that cats receive their vaccinations to avoid contracting the virus.

Other diseases listed, like canine distemper and canine parvovirus, primarily affect dogs; while feline leukemia is caused by a retrovirus, it has a different pathogenesis and does not present in the same acute and fatal manner as feline panleukopenia. Thus, feline panleukopenia stands out due to its viral origin and high mortality rates in affected cats.