Feline panleukopenia

Feline panleukopenia, more commonly known as feline distemper, is a viral infection affecting cats caused by feline parvovirus, a close relative of canine parvovirus. It is not related to canine distemper. Protection is offered by commercial feline distemper vaccine, which is usually a mixture of vaccines for several different diseases, including panleukopenia.

Transmission and symptoms
Panleukopenia is primarily spread through contact with an infected cat's bodily fluids, feces, or fleas. The virus may also sometimes spread through contact with bedding, food dishes, or even by handlers of infected cats.

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, usually bloody diarrhea, causing 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, infection causes a decrease in WBC, hematocrit and platelet counts on a CBC. This is often key in diagnosing panleukopenia.

Symptoms include depression, lethargy, loss of appetite, a high fever, vomiting, diarrhea, and loss of skin elasticity.

If a pregnant 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.

Vaccination controversy
In recent years, vaccination has become a controversial topic among veterinarians and pet owners. Recent studies have demonstrated that many vaccines are effective for several years, despite the common practice of "boosting" vaccines every year. This has particularly been demonstrated for the feline panleukopenia part of the FVRCP vaccine, which is a combined vaccine for feline viral rhinotracheitis, calicivirus, and panleukopenia. For this reason, the American Veterinary Medical Association (AVMA) and American Association of Feline Practitioners (AAFP) have developed vaccination guidelines recommending that FVRCP vaccinations generally be administered every 3 years (after completion of the kitten series of boosters).

FVRCP vaccines have also come under scrutiny of late due to possible risks to long term health. A study at Colorado State University noted an association between vaccination with parenteral (injectable) FVRCP vaccinations and development of antibodies against feline kidney tissue. Antibody development is hypothesized to develop when the immune system reacts to protein contaminants from the cell line used to cultivate vaccinial viruses. The cell line in question, the Crandell-Rees Feline Kidney (CRFK) cell line, was derived from a cat kidney. It is currently unknown whether this antibody development can lead to renal disease, though a recent follow-up study demonstrated evidence of inflammation on re-biopsy samples from some of the study cats. Feline injection-site sarcoma (vaccine-associated fibrosarcoma) has also occurred in association with FVRCP vaccines, though feline leukemia virus (FeLV) and rabies virus vaccines are more commonly implicated.

Given the studies documenting long-term efficacy and the creation of vaccine guidelines by authoritative organization like the AAFP, many veterinarians have adjusted their vaccine schedules. Some practitioners offer blood tests that measure the cat's levels of protective antibodies to determine which cats need to be vaccinated more frequently. Due to the extremely deadly and contagious nature of panleukopenia, the AVMA and AAFP strongly advocate the appropriate use of vaccinations against panleukopenia.