15. Canine infectious hepatitis and infectious laryngotracheitis.

Question 1

Infectious canine hepatitis, Fox encephalitis info ?

Answer 1

Infectious canine hepatitis, Fox encephalitis

• Rubarth-disease (1947) ➝ acute disease of dogs with vomiting, diarrhoea, bleedings and icterus
• Fox encephalitis (Green, 1928) ➝ haemorrhagic encephalitis of foxes
• Pathogen: CAdV-1
• Worldwide occurrence
• Canidae and Ursidae are susceptible
• Asymptomatic and lethal
• Frequent seropositivity due to immunisations

Question 2

CAdV-1 Pathogenesis?

Answer 2

CAdV-1 Pathogenesis

1. Viral intake: per os or via the conjunctiva
2. Tonsils, Peyer’s patches ➝ lymph nodes
3. Viraemia with lymphoid cells ➝ liver (hepatitis), brain (encephalitis), kidneys (glomerulonephritis), eyes (uveitis,

iridocyclitis)

4. CPE (cytopathogen effect), endothelial damage, DIC, Ag-Ig deposition (Type III. hypersensitivity)
   - Virus shedding with secretions such as the urine for up to 6 months
   - Long-term carriage in kidneys, persistent infections
   - Infection route is direct
   - After recovery, immunocomplex glomerulonephritis, uveitis

Question 3

Infectious canine hepatitis epizootiology?

Answer 3

Epizootiology

• Cross-protection: CAdV-2
• Sensitivity:

‣ 3-6 months ➝ mortalities

‣ Over 1 year ➝ mild or subclinical signs

• Maternal immunity protects for up to 3 months
• Incubation: 1-5 days

Question 4

Clinical signs of Infectious Canine hepatitis?

Answer 4

Clinical signs

Course

‣ Peracute: death within 1-2 days, non-specific clinical signs

‣ Acute: fever over 40℃ for 3-5 days which may look like a poisoning

‣ Extended: 1-2 weeks, oedema, convulsions, uveitis (grey/blue eyes) ➝ ‘blue eye’, cataracts, glaucoma,

ulceration

‣ Fox: acute encephalitis, convulsions, haemorrhages

• Usually in dogs under the age of 1 year

‣ Sudden death may occur

‣ Fever, depression, lymphadenomegaly (popliteal and submandibular lymph nodes may be swollen), oedema,

icterus, anorexia, vomiting, seizures, disorientation, coma ➝ death

‣ Corneal oedema, anterior uveitis, photophobia

Question 5

Canine infectious hepatitis Pathology,Histopathology?

Answer 5

Pathology, Histopathology

• Oedema, haemorrhages
• Enlarged, yellow liver
• Centrolobular hepatocyte necrosis, hepatitis, icterus
• Serosa haemorrhages, nephritis, gall bladder oedema
• Nuclear inclusion bodies (Cowdry A), smudge cell
• Liver parenchymal cell degeneration
• Invasion of inflammatory cells

Question 6

Diagnosis of infectious Canine hepatitis?

Answer 6

Diagnosis

• Laboratory tests

‣ Leukopenia, lymphopenia, neutropenia

‣ Later neutrophilia, lymphocytosis

‣ Elevated serum ALT, AST, ALP levels

‣ Bilirubinuria, proteinuria

‣ Prolonged clotting time, DIC (coagulation abnormalities)

• Direct virus detection

‣ Immunofluorescence, immunoperoxidase staining

‣ Virus isolation in canine or swine cells

‣ PCR ➝ main detection method

• Serology: VN, IIF, ELISA, HAI, CF, AGID

Question 7

Differential diagnosis of Infectious canine hepatitis?

Answer 7

Differential diagnosis

• Lab values: CPV-2, CPV-1, CDV, CHV
• Vomiting, diarrhoea: CPV-2, CDV
• Ocular lesions: CHV, CDV
• Encephalitis: rabies, distemper
• Icterus and hepatic problems: Leptospira, Babesia

Question 8

Treatment and prevention with immunisation of infectious canine hepatitis?

Answer 8

Treatment

• Clinical management: IV hydration, glucose, liver protective drugs
• Hyperimmune serum

Prevention with immunisation

• Attenuated and inactivated CAdV-1
• Attenuated CAdV-2
• Usually component of polyvalent vaccines
• Basic immunisation from 2-3 months of age
• Yearly or every 2nd or 3rd year (repetition)

Question 9

Canine Infectious Laryngotracheitis (Kennel cough) epizootiology?

Answer 9

Canine Infectious Laryngotracheitis (Kennel cough)

• Mild febrile disease of dogs with upper respiratory tract inflammation
• Causative agent: CAdV-2

Epizootiology

• Distribution: worldwide
• Clinical manifestations usually in young dogs
• Alone rarely induces clinical signs
• Crowded keeping conditions, co-infections

‣ Parainfluenza virus 2, Canine respiratory coronavirus, canine herpesvirus

‣ Bordetella bronchiseptica, Pasteurella multocida ➝ Kennel cough syndrome

Question 10

Pathogenesis and clinical signs of Canine infectious Laryngotracheitis?

Answer 10

Pathogenesis

• Air-borne infection, virus multiplication in upper respiratory tract mucosa
• Rhinitis, laryngitis, tracheobronchitis, bronchiolitis

Clinical signs

• Mild fever, nasal discharge, dry coughing
• With co-infections pneumonia

Question 11

Diagnosis, treatment and prevention of canine infectious Laryngotracheitits?

Answer 11

Diagnosis

• Case history, clinical signs, quick spread in …
• Virus isolation in canine cells
• Serology: VN, eLISA

Treatment-

• Symptomatic: respiratory support + antibiotics for co-infections

Prevention

• Improved keeping conditions (crowding)
• Immunisation (from 2-3 months, usually polyvalent vaccines)

Question 12

Fox encephalitis?

Answer 12

Fox encephalitis (CAdV-1)

• Nervous signs are more important

Clinical symptoms

• Inappetence
• Apathy
• Change in behaviour
• Later incoordination
• Convulsions
• Death

Pathology

• Hepatitis
• Lymphohistiocytic encephalitis

‣ Lymphoid cell cuffing around the blood vessels

‣ Neutron degeneration

‣ Glial nodules

• Intranuclear inclusion bodies are pathognomic (neurons, hepatocytes, urinary bladder epithelial cells)

Diagnosis

• PCR

- Differential diagnosis: Rabies, Distemper