Viral Disease - Clinical and Pathological Changes

Question 1

Clinical signs in viral disease

Answer 1

Different viruses cause different clinical signs depending on which body systems are affected
May be acute or chronic

Question 2

Acute signs of viral disease

Answer 2

Majority of viral infections are acute
□ Pyrexia
□ Depressed
□ Off food
□ Lethargic

Secondary bacterial infections are common for intestinal and respiratory viruses

Question 3

Examples of acute viral disease

Answer 3

Cat Flu
* FHV
* FCV
Calf respiratory disease
Canine Parvovirus

Question 4

Cat Flu Clinical Signs

Answer 4

• Calicivirus, herpes virus (FCV, FHV)
  ○ Nasal and ocular discharge
  ○ Pyrexia
  ○ Anorexia
  ○ Lethargy
  FHV - Corneal ulcers
  FCV - Oral ulceration

Question 5

Calf Respiratory Disease Signs

Answer 5

Not pathognomonic
* Quiet
* Not as obvious as in small animals
* Cough
* Nasal/ocular discharge
* Pyrexia
* Depression

Question 6

Canine Parvovirus Signs

Answer 6

Mostly seen in unvaccinated puppies
* Vomiting
* Bloody diarrhoea
* Pyrexia
* Neutropenia
* Vilus stunting, crypt dilation and necrosis

Question 7

Chronic viral disease examples

Answer 7

Sequel to acute disease
* Chronic rhinitis in cats
* Lentiviruses
* Herpesviruses

Question 8

Chronic rhinitis in cats

Answer 8

After having cat flu may have significant turbinate damge
* Causes recurrent chronic infections

Question 9

Lentiviruses

Answer 9

Long drawn out infections
○ FIV - immunosuppression
○ Occasionally causes lymphomas

Question 10

Herpesviruses

Answer 10

Exhibits latency
Presents at times of stress

Question 11

Oncoviruses

Answer 11

• Retroviruses
  ○ Feline Leukaemia virus (FeLV)
  ○ Feline Immunodeficiency Virus (FIV)
  ○ Jaagsiekte sheep retrovirus (JSRV)
  ○ Koala retroviruses (KoRV)
• Herpesviruses
  ○ Marek’s Disease in chickens
• Papillomaviruses
  ○ Bovine Papillomavirus 2&4 (BPV2-4)

Question 12

Viruses with immunosuppression effects

Answer 12

Lack of immune response
* FIV
* Infectious Bursal Disease (Poultry)
Depletion of lymphocytes in bursae
* BVDV
Immune suppression
Predispose to respiratory and intestinal disease
* Parvoviruses
Infect bone marrow
Kill developing immune cells

Question 13

Viruses with immunopathology effects

Answer 13

Inappropriate immune response
* Feline Infectious Peritonitis (FIP)

Question 14

Feline Infectious Peritonitis Pathogenesis

Answer 14

Type 3 Hypersensitivity
* Forms immune complexes between virus and antibodies produced by host
* Sit within capillaries and cause immune reponse
* Complement activation
* Leakiness of vessels - fluid accumulation in body cavities

Question 15

How useful are clinicopathological changes?

Answer 15

Not very useful for diagnoses
Will reflect underlying pathology - see how severe tissue damage is
May pick up inflammatory response