The virus primarily attacks the lining of the gastrointestinal tract, causing internal ulceration and, ultimately, total sloughing of the intestinal epithelium. This results in profuse and usually bloody diarrhea, severe dehydration, malnutrition, anemia, and often death; mortality rate 60-90%.
The virus causes a decrease in the cat's white blood cells, thus compromising its immune system. Typically, it also causes a decrease in hematocrit and platelet counts on a complete blood count. This is often key in diagnosing panleukopenia.
Other symptoms include depression, lethargy, loss of appetite, fever, vomiting, loss of skin elasticity due to dehydration and self-biting in the tail, lower back and back legs.
If a cat is exposed during pregnancy, the virus can cause cerebellar hypoplasia in her offspring. This is why administering modified live feline panleukopenia vaccine during pregnancy is discouraged.
It is impossible for a cat to spread Panleukopenia to a dog, as dogs can not contract the virus.