Feline Panleucopenia

Introduction

Feline Parvovirus, also known as feline infectious enteritis (FIE) or feline panleukopenia is a non-enveloped virus, capable of persisting for long periods of time in the enviroment.

It infects the lymph nodes of the oropharynx and the nasopharynx, and the spreads to other tissues. It infects and kills actively replicating cells. Kittens are most susceptible, but unvaccinated older cats can also become infected.

Hosts

Feline Parvovirus is most commonly seen in cats, but is also seen in minks, racoons, and pandas.

Pathogenesis

Feline Parvovirus kills the stem cells of the villi. The villi tip cells turnover normally but are not being replaced, leading to stunted villi and malabsorption. Clinical signs include pyrexia, severe enteritis (often bloody), dehydration, leukopenia, and anemia.

Severe vomiting and diarrhoea may also occur. This is often thin, watery and foul-smelling, but may also be blood-tinged.

Neonatal kittens less than 2 weeks show cerebellar hypoplasia. This leads to problems with coordination and balance.

The virus targets rapidly dividing cells: lymph nodes, bone marrow, crypts of small intestine. The breakdown of lymphoid tissue leads to a decreased white blood cell count, and destruction of lymphoid and myeloid stem cells.

Animals who have contracted the virus usually die despite treatment, due to the extensive dehydration.

Epidemiology

Infection may be via direct contact or by fomites. Subclinical infection may also occur.

Diagnosis

1.Clinical signs.

2. Haematology.

3. Analysis of faeces; use of an ELISA to detect the virus antigen or detecting the virus DNA, using a PCR (Polymerase chain reaction.)

4. Evidence of exposure to virus - detect antibody to virus within the blood.

Control

Modified live and inactivated virus vaccines are avaliable, with boosters every 1-2 years required. One should also try to prevent exposure to kittens with feline panleukopenia.

Parvovirus Enteritis

Since the introduction of a vaccine, this disease is now relatively uncommonly seen. Over the last 10/15 years this has been seen primarily in the cat, but it is now also seen in the dog.

Pathology

Gross

The virus targets crypt cells and lymphoid areas,causing villus atrophy. In the cat, the intestine becomes thickened, turgid and swollen, with a pale, dull and mottled appearance.

The contents appear rather dry, and this becomes increasingly evident lower down the gut.

Lower down in the gut, enteritis is apparent. In the cat this is fibrinous enteritis, and in the dog it is haemorrhagic.

Histological

The crypt lining cells undergo complete necrosis, but very little inflammation is seen. Fibrinous exudates may be seen on surface of the mucosa. However,the submucosa and lamina propria are often unaffected. Cyst-like structures are seen in the deepest parts of the glands of the intestinal mucosa after only a few days of infection. These cystic glands are lined with flattened epithelial cells.

Inclusion bodies may also be seen, but these are often very hard to find.

The Lymph nodes appear pale and oedematous, and almost aplastic. The Bone marrow appears pale and fatty looking and is depleted of cells.