Vetiology

Adenoviruses are linear, double-stranded DNA viruses which infect a wide variety of mammals and birds. Two have been identified in the dog: canine adenovirus type 1 (CAV-1) which infects most of the major organs causing, amongst other diseases, hepatitis, and canine adenovirus type 2 (CAV-2) which causes respiratory and enteric diseases.

Canine adenovirus type 1 causes canine hepatitis. The virus invades the dogs liver, causing swelling, cell damage sometimes liver haemorrhage and often acute death due to shock. An infected dog will shed the virus in the faeces and urine. Other dogs become contaminated via the mouth or nose and the virus then lodges in the tonsils. The virus is not airborne. The incubation period is 4 to 7 days. Canine hepatitis was first documented in the silver fox in 1925, but the disease did not appear in domestic dogs until the 1930s and 1940s.

Symptoms include fever, lethargy, tonsillitis, abdominal distension and pain, loss of appetite and a pale colour. Often there is vomiting. Some dogs will develop the classic hepatitis blue eyes. The is due to odoema (fluid swelling) of the cornea of the eye. In severe acute cases, especially pups, death can occur in 1 to 2 days. If dogs can survive the initial few days, they should recover and have lifelong immunity. However, regular vaccination is a preferntial.



Canine adenovirus type 2 is related to the hepatitis virus and is one of the causes of infectious tracheobronchitis, also known as kennel cough. Vaccination against adenovirus-2 will not prevent infection with this virus but limits its severity so the chance of secondary bacterial infection and complications occurring is minimized. In most cases of kennel cough, the disease is multifaceted and will include a combination of bacterial and viral agents.

Normally, symptoms of kennel cough will develop within a week after a dog has been exposed. The most common symptoms are a dry, hacking cough followed by retching, and coughing up a white foamy discharge. The cough is brought on by an inflammation of the trachea (windpipe) and bronchi (the air passages to the lungs). Some dogs also develop conjunctivitis ("pink eye"), rhinitis (inflamed nasal mucous membrane), and a nasal discharge.