Lecture 4 -- Feline panleucopenia, cowpox and influenza virus

These flashcards cover essential topics and details regarding feline viral infections, their pathogenesis, clinical signs, treatments, and prevention strategies.

What is feline panleucopenia? Which virus causes feline panleucoenia?

• Caused by feline parvovirus

  • Feline panleucopenia is also called feline parvovirus

• “Panleucopenia” = Reduction in white blood cells

What type of virus is feline panleukopenia?

• DNA virus

  • Not mutate very much

• Non-envelooped

  • Resistnat to many disinfectants → Survives long term in contaminated environments

Which type of cells does parvovirus target, and why?

• Targets rapidly dividing cells

• Reason:

  • It is a small DNA virus that does not encode its own DNA polymerase → Must use the host cell’s DNA replication machinery to copy its genome → Therefore, it targets cells that are actively replicating DNA

Which tissues (that have rapidly dividing cells) are targeted in feline panleucopenia, and what clinical signs result ?

1. Intestinal villus crypt epithelium

   • Crypt cells are rapidly dividing to replace villus cells

     • Clinical sign: Enteritis

2. Bone marrow and lymphoid tissue

   • Constant production of WBCs requires rapid cell division

     • Clinical sign: Panleucopenia = Decreased production of white blood cells

3. Late gestation/ neonatal cerebellum

   • High mitotic activity during brain development

     • Clinical sign: Cerebellar hypoplasia (Decreased no. of cell)

4. Early pregnancy

   • Clinical sign: Foetal death → Abortion

What are the other clinical signs of feline panleucopenia?

• Sudden death

• Profuse diarrhoea

• Pyrexia

• Depression

• Anorexia

How is feline panleucopenia treated?

• Fluid therapy (For enteritis)

• Antibacterials (Control secondary infection)

• Interferon (Not licensed)

How is feline panleucopenia diagnosed?

• Clinical signs and history

  • Is the cat vaccinated?

• Faecal PCR or lateral flow test

• ELISA

• Post mortem histopathology (Especially when there is an outbreak)

  • Shorten and loss of intestinal vilii

  • Depletion of gut lymphoid tissue

Is there vaccination for feline parvovirus (feline panleucopenia)?

Yes (Live or inactivated)

• Highly effective (If the cat is vaccinated against feline panleucopenia, it is very unlikely to get clinical disease)

How is feline panleucopenia prevented, apart from vaccination?

• Strict biosecurity

• Elimination of virus from the environment

  • Remove the contaminated material first before cleaning the environment

  • Use disinfectants proven effective against parvovirus

Is feline parvovirus (FPV) related to canine parvovirus (CPV-2)? Could they infect both species?

Yes

• CPV-2 is likely evolved from FPV via an intermediate host in late 1970s

• CPV-2 can only infect dogs while FPV can only infect cats

What happened over time after CPV-2 has evolved from FPV? Why does it matter?

• CPV continued to mutate, producing new variants (CPV-2a → CPV-2b → CPV-2c)

• Clinically important because these variants has cross-species transmission potential (Can infect dogs, as well as cats)

Does feline panleucopenia (FPV) vaccination protect against CPV-2 variants?

Yes

• Prevents clinical signs of infection

• Prevents virus shedding, reducing the risk of transmission

What type of virus is cowpox, affecting cats?

Cowpox is an orthopox, DNA virus

What is the natural reservoir of cowpox? Which group of cats are at highest risk?

Rodents, particularly bank voles and wood mice

• Cats get infected by hunting/ eating infected rodents

• Outdoor/ rural hunting cats are at highest risk (Rare in indoor cats)

Can cowpox be transmitted to humans?

Yes

• Cowpox is a zoonotic disease

What are the clinical signs of cowpox in cats?

• Start with a single primary lesion (at site of a rodent bite)

• Widespread multiple small skin lesion 1-3weeks later

Can cats infected with cowpox recover?

Yes.

• Most animals recover uneventfully

• Immunosppressed cats may develop systemic illness or uncontrolled lesion

What should be avoided when treating cats infected with cowpox? Why?

Avoid use of steroids

• Lesion of cowpox is often mistaken for flea allergy dermatitis, which requires use of steroid

• Steroid suppress the immune system → Worsen cowpox infection

Can domestic cats get H5N1 avian influenza?

Yes, but infection is rare.

Avian influenza viruses circulating in birds are usually of low pathogenicity. How does avian influenza become highly pathogenic?

To become infectious, one of the viral proteins must be cleaved by a host cell protease

• Low-pathogenic strains:

  • Protease is found mainly in the respiratory and intestinal tracts, where the virus replicates → Infection is typically limited to these tissues = Mild, flu-like clinical signs

• Highly pathogenic strains:

  • Mutations in hemagglutinin (HA) protein happens→ Additional amino acids inserted → Proteases for cleaving that mutated HA protein are ubiquitously 普及 distributed throughout the body→ Severe polysystemic infection (Not only respiratory or GI tract, but also CNS and other organs)

Are influenza viruses RNA or DNA viruses?

RNA enveloped virus

• High mutations rate → Antigenic drift

• Sensitive to soap and disinfectants

How do cats become infected with avian influenza H5N1?

Through contact with infected domestic or wild birds., their droppings

Clinical signs of H5N1 in cats

• Fever (raised body temperature)

• Lethargy / decreased activity

• Conjunctivitis

• Laboured breathing

Can infected cats transmit H5N1 (Cat-to-cat transmission VS Cat-to-human transmission)? If yes, how?

• Yes

  • Cat-to-cat transmission is possible

  • Cat-to-human transmission is very rare (Humans are more likely to get infection directly from birds)

• Cats can excrete virus via respiratory and digestive tracts

How can owners prevent infection in cats?

• Avoid contact with:

  • Dead or sick wild birds

  • Bird droppings, feathers, or carcasses

  • Contaminated feed or water bowls that wild birds could have accessed

• Do not feed cats raw poultry, game, or wild bird meat

Is there vaccination of influenza virus for cats, and if so, what types are they?

Yes

• Have both live attenuated and inactivated

What are core vaccines recommended for cats?

Feline calicivirus (FCV)

Feline parovirus (FPV) = Feline penleukopenia

Feline herpes virus 1 (FHV-1)

What is the recommended feline vaccination schedule according to the VGG?

• Initial vaccination: 8–9 weeks of age

• Second dose: 3–4 weeks after the first

• Third dose: 14–16 weeks of age

• Booster: at 1 year of age, then every 3 years thereafter

Why do we have to consider maternal antibodies (MDA) when planning vaccination?

Too early:

• High MDA levels can block vaccine efficacy

  • Maternal antibodies circulating in the kitten’s blood may neutralise the vaccine antigen before the kitten’s immune system can respond → No active immunity develops by its own even though it was vaccinated

Too late:

• Kitten have lost MDA by 8 weeks → Kitten may be unprotected if we vaccinate them too late

What is the possible adverse reaction of vaccination in cats?

1/10000 Injection site (Scruff of neck) sarcomas