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==Introduction==

==Introduction==

Canine Adenovirus 1 (CAV-1) was first isolated by Carbasso in 1954¹ from a case of acute hepatitis in the dog. This virus found to be identical to the virus isolated in 1947 by Rubarth² from a dog showing acute liver lesions, and so CAV-1 was originally known as Infectious Canine Hepatitis (ICH) virus. Subsequently, CAV1 infection was shown to be common in young dogs worldwide, with 82% of British dogs displaying neutralising antibody titres by nine months of age³. It has also since been demonstrated that CAV1 has a role in diseases other than [[Infectious Canine Hepatitis]], such as [[Canine Infectious Tracheobronchitis]].

Canine Adenovirus 1 (CAV-1) was first isolated by Carbasso in 1954¹ from a case of acute hepatitis in the dog. This virus found to be identical to the virus isolated in 1947 by Rubarth² from a dog showing acute liver lesions, and so CAV-1 was originally known as Infectious Canine Hepatitis (ICH) virus. Subsequently, CAV1 infection was shown to be common in young dogs worldwide, with 82% of British dogs displaying neutralising antibody titres by nine months of age³. It has also since been demonstrated that CAV1 has a role in diseases other than [[Infectious Canine Hepatitis]], such as [[Canine Infectious Tracheobronchitis]].

CAV-1 is a Mastadenovirus, member of the [[Adenoviridae - Overview|Adenoviridae]] family.

 

CAV-1 is a member of the Adenoviridae family, a group double-stranded DNA viruses with an  icosahedral nucleocapsid. Many Adenoviridae have been isolated from mammals and birds, but only a small number of these cause significant veterinary disease. The family consists of four genera: Mastadenovirus, Aviadenovirus, Atadenovirus and Siadenovirus. Canine adenovirus 1 is a Mastadenovirus.

 

 

 

The virus genome is contained within a non-enveloped icosohedral nucleocapsid, which comprises capsomeres (called hexons) and twelve vertex capsomeres  (called pentons). A fibre antigen protrudes from each of the twelve pentons, and this attaches to host cell receptors as well as being a type-specific haemagglutinin.  This fibre antigen is a feature specific to the Adenoviridae. The hexon of mammalian adenoviruses contains a cross-reacting group antigen.

==Hosts==

==Hosts==

==Transmission==

==Transmission==

CAV-1 infection occurs by inhalation and ingestion, after shedding in the urine, faecs or respiratory secretions. Transmission my be by direct contact, or by indirect contact and fomites such as handlers or infected surfaces. Following infection, the virus initially replicates in the tonsils and Peyer's patches. A viraemia is produced, and CAV-1 secondarily localises and replicates in the liver and kidneys.

CAV-1 infection occurs by inhalation and ingestion of the virus after shedding in the urine, faeces or respiratory secretions. Transmission may be by direct contact, or by indirect contact such as via handlers or infected surfaces. Following infection, the virus initially replicates in the tonsils and Peyer's patches. A viraemia is produced, and CAV-1 secondarily localises and replicates in the liver and kidneys.

Canine adenovirus 1 is resistant to environmental inactivation, and can survive for days on fomites at room temperature. Inactivation requires the use of phenol, sodium hydroxide or iodine based disinfectants, or steam cleaning.

Canine adenovirus 1 is resistant to environmental inactivation, and can survive for days on fomites at room temperature. Inactivation requires the use of phenol, sodium hydroxide or iodine based disinfectants, or steam cleaning.

==Clinical Features==

==Disease==

Although there is evidence for a high incidence of infection among the non-vaccinated canine population, this is not matched by a similar occurance of clinically detectable infectious hepatitis since many infections are subclinical. In additions to [[Infectious Canine Hepatitis]], CAV-1 has been shown to be involved in several other types of disease. These include encephalopathy ⁴, ocular lesions, neonatal disease⁵, chronic hepatitis⁶, and interstitial nephritis⁷. The virus can be isolated from throat swabs or lungs from some dogs with respiratory disease, and CAV-1 is known to be of importance in [[Canine Infectious Tracheobronchitis]].

Although there is evidence for a high incidence of infection among the non-vaccinated canine population, this is not matched by a similar occurrence of clinically detectable infectious hepatitis since many infections are subclinical. In additions to [[Infectious Canine Hepatitis]], CAV-1 has been shown to be involved in several other types of disease. These include encephalopathy ⁴, ocular lesions, neonatal disease⁵, chronic hepatitis⁶, and interstitial nephritis⁷. The virus can be isolated from throat swabs or lungs from some dogs with respiratory disease, and CAV-1 is known to be of importance in [[Canine Infectious Tracheobronchitis]].

==Pathology==

==Pathology==

Subclinical infection with canine adenovirus 1 most typically causes a mild bronchointerstitial pneumonia, although a necrotising bronchiolitis  may occur in immunocompromised dogs. This is seen histologcally as necrosis of the bronchiolar and alveolar epithelium, pulmonary oedema and hyperplasia of type II pneumocytes.  

Subclinical infection with canine adenovirus 1 most typically causes a mild bronchointerstitial pneumonia, although a necrotising bronchiolitis  may occur in immunocompromised dogs. Bronchointerstitial pneumonia is seen histologically as necrosis of the bronchiolar and alveolar epithelium, pulmonary oedema and hyperplasia of type II pneumocytes.  

In [[Infectious Canine Hepatitis]], canine adenovirus 1 principally causes damage to the endothelium and to hepatic cells. Endothelial damage results in widespread petechial haemorrhages, and hepatic damage may be visualised as an enlarged liver, mottled with areas of necrosis. Microscopically, centrolobular necrosis is seen in the liver, and adenoviral nuclear inclusion  bodies may be observed in Kupffer and parencymal cells. Glomerulonephritis and occular pathology are not uncommon findings.

In [[Infectious Canine Hepatitis]], canine adenovirus 1 principally causes damage to the endothelium and to hepatic cells. Endothelial damage results in widespread petechial haemorrhages, and hepatic damage may be visualised as an enlarged liver, mottled with areas of necrosis. Microscopically, centrolobular necrosis is seen in the liver, and adenoviral nuclear inclusion  bodies may be observed in Kupffer and parenchymal cells. Glomerulonephritis and occular pathology are not uncommon findings.

The pathology exhibited in [[Infectious Canine Tracheobronchitis]] varies with other contributing organisms and the severity of disease.

The pathology exhibited in [[Infectious Canine Tracheobronchitis]] varies with the other contributing organisms and the severity of disease.

 

==References==

==References==

#Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''' ''Merial''  

#Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''' ''Merial''  

[[Category:Adenoviridae]][[Category:Dog]]

 

[[Category:To_Do_-_Lizzie]]

 

 

[[Category:Adenoviridae]][[Category:Dog Viruses]][[Category:Respiratory Diseases - Dog]]

 

 

[[Category:Expert_Review]]

[[Category:Respiratory_Viral_Infections]]

[[Category:Respiratory_Viral_Infections]]