Infectious Canine Hepatitis (ICH)

Infectious Canine Hepatitis (ICH) also known as Rubarth’s disease and contagious hepatitis in animals.

Infectious Canine Hepatitis (ICH) is a contagious viral disease of dogs, characterized by biphasic fever, congestion of mucous membrane, severe depression, leukopenia and prolonged bleeding time (thrombocytopenia).

Etiology

• Infectious Canine Hepatitis (ICH) is caused by adenovirus- 1 (CAV-1) which is antigenically related to CAV-2.
• It is a linear non enveloped double stranded DNA viruses.

Epidemiology

• Distribution: Worldwide.
• Dogs and foxes are mostly susceptible.
• All age group of dogs are susceptible.
• Dogs less than one year old is highly susceptible to acute form of the disease.

Source of infection

• The virus is excreted through faeces, urine and saliva of infected animals.
•  The clinically recovered dogs shed the virus in their urine for greater than 6 months.

Transmission

• Ingestion of food  and water contaminated by urine, faeces and saliva of the infected animal.

Pathogenesis

Clinical manifestation

• Incubation period for this disease is 6-9 day.
• Biphasic fever.
• Increased rectal temperature (103-06^oF), accelerated pulse and respiratory rate.
• Anorexia, vomition, abdominal pain and diarrhoea with or without evidence of haemorrhage.
• Enlargement of tonsilar lymph node.
• Coughing.
• Cervical lymphadenomegaly.
• Subcutaneous edema of the head, neck and dependent portion of trunk.
• Petechial and ecchymotic haemorrhage on buccal mucosa, haemorrhage around the deciduous teeth and epistaxis.
• Icterus is uncommon in acute form of ICH.
• Abdominal distension is due to accumulation of serosanguineous fluid or haemorrhage
• Tucked up appearance of abdomen on palpation of xiphoid region.
• Transient corneal opacity and edema is due to iridocyclitis. The condition is called as blue eye
• CNS signs include depression, disorientation, seizures and terminal coma.
• Death in dog can result from damage to brain (hepatoencephalopathy), lungs and other parenchymal organs or from the development of DIC.

Complication

• Dogs are more prone to bacterial pyelonephitis as a result of renal damage after ICH infection.
• Disseminated intravascular coagulopathy.
• Decreased synthesis of clotting factors in liver is leading to bleeding defect.

Necropsy Finding

• The abdominal cavity contain  bright red colour fluid.
• Liver  is enlarged, dark and mottled appearance, fibrinous deposit on the surface of the liver.
• Gall bladder is enlarged and edematous.
• Enlarged spleen.
• Greyish necrotic foci on the surface of kidney cortex.

Diagnosis

• Based on clinical signs and lesions.
• Haematological findings- leukopenia, lymphopenia, neutropenia and thrombocytopenia.
• Proteinuria (TP >50 mg/ dl), increased concentration of protein in CSF fluid and aquous humor.
• Increased level of AST, ALT, Bilirubin and ammonia level in serum.
• Hypergammaglobinemia and Hypoglycemia.
• Antigen detection by PCR and immunohistochemical staining of the tissue.
• Serological tests – AGID, CFT and VNT are used to detect antibodies in serum.

Treatment

• Symptomatic and supportive treatment can be tried.
• Fluid therapy with polyionic isotonic ringers’ solution.
• For animal with hypoglycemia, hypertonic glucose infusion should be continued at the rate of 0.5-0.9g/ kg/hr for efficient utilization.
• Blood or plasma transfusion can be tried, when an animal suffering from severe anaemia.

Therapy is directed to reduce the ammonia concentration in blood, which is achieved by decreasing the  protein catabolism ammonia and reduce the  ammonia resorption in renal tubules:

• Decreased feeding of protein diet.
• Cleansing and evacuation of bowel content with acidifying ammonia.
• Non absorbable antibacterial drug (Neomycin) is given to reduce the ammonia producing bacteria in the bowel.
• Renal reabsorption is reduced by use of urinary acidifier (Ascorbic acid) and oral or  parenteral administration of potassium.

Prevention

• Vaccination of pups at 8-10 weeks and 10-12 weeks of age with modified live vaccine and  revaccination should be done every 3 years.
• Combined vaccine (DHLPPi vaccine) at 6-8 weeks of age and booster dose 3-4weeks later after that  annual revaccination every year.
• Cleaning and disinfection of shed with 1-3 % sodium hypochlorite.