Feline Panleucopenia

Antigenicity

• One serotype

Hosts

• Cats
• Mink
• Raccoons
• Pandas

Pathogenesis

• Also known as Feline Infectious Enteritis and Feline Panleukopenia
• Often fatal
• Pyrexia, severe enteritis (often bloody), dehydration, leukopenia, anemia
• Kittens <2 weeks show cerebellar hypoplasia
• Kittens more susceptible than cats
• Oral infection
• Initial replication in pharyngeal lymphoid tissue
• Viremia
• Virus targets rapidly dividing cells: lymph nodes, bone marrow, crypts of small intestine

Epidemiology

• Infection by direct contact and fomites
• Subclinical infections occur
• Virus excretion can be persistent
• Endemic worldwide

Diagnosis

• Clinical signs
• Hematology: leukopenia
• Can be confirmed by haemagglutination (HA) or ELISA using feces

Control

• Inactivated vaccines are available and essential for boarding
• Administered parenterally post-weaning to induce a systemic immune response to neutralize viremia
• Annual booster

Parvovirus Enteritis

• Parvovirus enteritis is also know as feline infectious enteritis or feline panleucopenia
• Since a vaccine is available, this disease is now uncommon.
• Over the last 10/15 years this has been seen primarily in the cat, but it is now also seen in the dog.

Clinical

• Manifests mainly in cats under 6 months old.
• Common in groups of unvaccinated cats.
  • Produces big outbreaks, with vomiting and pyrexia.
• Severe vomiting and diarrhoea occur.
  • diarrhoea is thin, watery and foul-smelling, and may also be blood-tinged.
    • Animals usually die despite treatment- die from dehydration.
• Animals suffer from fever.
• Pancytopaenia also occures.
  • White blood cell count drops very low so as to become almost non-existent.
    • Drops to 1/ml from 10000/ml.
  • Animals may therefore also die from other infections.

Pathology

Gross

• Virus targets crypt cells and lymphoid areas.
  • Causes villus atrophy.
• In the cat, the intestine is thickened, turgid and swollen.
  • Has a pale, dull and mottled appearance.
  • The contents are rather dry - this gets worse lower down the gut.
• Areas of depression in the mucosa can be seen in the upper small bowel.
  • Due to necrosis of tissue overlying Peyers patch.
• Lower down in the gut, enteritis is apparent.
  • Cat- fibrinous.
  • Dog- haemorrhagic.
    • Blood in lumen.
  • Inflammation sometimes doesn't appear very severe.
• There may be very few lesions
  • Histology is usually required for diagnosis.
• A radiomimetic virus.
  • Affects all rapidly dividing cells and destroys them.
    • E.g. epithelium in the base of the crypts of small intestine are killed.

Histological

• The crypt lining cells undergo complete necrosis, but very little inflammation occurs.
  • Collapse of villous architecture.
• May be fibrinous exudates on surface of mucosa.
• The submucosa and lamina propria are not affected and are left intact.
  • Many neutrophils in the lamina propria.
• Cyst-like structures are seen in the deepest parts of the glands of the intestinal mucosa, if the animal survives for more than a few days.
  • Flattened epithelial cells line these cystic glands.
    • Are enterocytes trying to repair the damage.
    • However, animals usually die from dehydration or secondary infection before the mucosa recovers.
• Inclusion bodies may be seen, but these are very hard to find.
• May get lymphocyte invasion of mucosa.
• Lymph nodes appear pale and oedematous, and almost aplastic.
• Bone marrow appears pale and fatty looking and is depleted of cells.