Canine Adenovirus Infection

Canine adenovirus (CAV)'s global ubiquity poses significant threats to canine health, while also jeopardizing animal health. This has garnered substantial attention worldwide. At BioVenic, we possess an in-depth understanding of CAV's biological characteristics, epidemiology, pathogenic mechanisms, and clinical symptoms. Our commitment is to provide tailored diagnostic solutions and tools, as well as vaccines to our customers.

Etiology

CAV is a member of the Adenoviridae family, Mastadenovirus genus. The CAV genome is a linear, non-segmented, double-stranded DNA virus approximately 30-31 kb in length. CAV virus has no envelope and has an icosahedral symmetrical structure with a diameter of about 70-100 nm. CAV is divided into two serotypes, canine adenovirus type 1 (CAV-1) mainly causes canine infectious hepatitis, bear and fox encephalitis, and can cause eye damage; canine adenovirus type 2 (CAV-2) mainly causes canine Infectious laryngotracheitis and pneumonia in puppies. We have introduced the infectious canine hepatitis caused by CAV-1 in detail. This page provides comprehensive information on all aspects of infection caused by CAV-2.

Fig.1 Distinct stages of axonal transport in CAV-2.^1,2

Geographical Distribution

CAV infection occurs worldwide at very high rates. CAV-2 was first isolated from the upper respiratory tract of dogs by Ditfield in 1962 during an outbreak of canine infectious laryngotracheitis. The geographic distribution of CAV-2 spans different regions worldwide.

Susceptible Animals

CAV-2 mainly infects puppies, foxes, wolves, etc. Infection is particularly serious in puppies under 4 months of age. It is often co-infected with canine distemper virus and Bordetella, causing kennel cough, and the onset is most obvious in winter.

Source of Infection

Sick animals and recovered virus carriers are the main source of CAV infection. There are a lot of viruses in eye and nose secretions, saliva, feces, and urine secreted by sick animals. On the other hand, there are also a lot of viruses in the cages contaminated by it, and the external environment is easily polluted for a long time. The virus in the urine of recovered animals can last for more than 6 months.

Transmission

• The virus is spread primarily through contact with infected dogs.
• Indirect transmission is also one of the ways of CAV transmission.
• Because CAV-2 is transmitted through mucous membranes and air, it can spread rapidly in immune-compromised dog populations.

Pathogenesis

After entering the canine body, CAV-2 mainly infects non-ciliated bronchial epithelial cells, epithelial cells of the nasal mucosa, pharynx and tonsillar fossa, mucosal cells of trachea and bronchi, and type 2 alveolar epithelial cells, causing mild and acute upper respiratory infection. Often co-infected with other respiratory viruses or bacteria, causing acute paroxysmal cough. CAV-2 can also infect intestinal epithelial cells, causing canine gastrointestinal diseases.

Signs and Symptoms

CAV-2 can cause respiratory and gastrointestinal symptoms in infected animals, which may manifest as:

Diagnosis

Current methods for diagnosing CAV-2 by laboratory techniques include the following:

• Electron Microscope: CAV-2 has obvious morphological characteristics. The size and structure of virus particles can be observed under the electron microscope by negatively staining the mixed culture of the virus and cells with phosphotungstic acid.
• Virus Isolation and Identification: Use canine kidney passage cells to isolate the CAV-2, which is also recommended by the OIE identification method.
• Veterinary Immunodiagnostic: Use the prepared tissue fluid as the antigen and then perform the complement fixation test, or use the concentrated cell-infected mixture as the antigen and use the agar gel immunodiffusion (AGID) assay to detect the antibody in the serum. Fluorescence in Situ hybridization (FISH) also be used to detect the CAV antigen in the heart, liver, spleen, and other tissue sections, prints, and infected cultures.
• Veterinary Molecular Diagnostics: PCR and quantitative real-time PCR can distinguish and identify CAV-1 and CAV-2.

Treatment and Prognosis

No specific therapy. If a dog is infected with CAV-2, it is important to administer antibacterial and anti-inflammatory medication first to boost its resistance. In the case of a rapid course of the disease, it is generally possible to inject hyperimmune serum into the sick dog for emergency treatment. Antiviral fluids can also be used for symptomatic treatment. Cooperate with antibiotics, and then supplement electrolytes and glucose to prevent secondary infection in sick dogs.

Sick dogs usually have a good prognosis.

Prevention and Control

• Vaccination is a key preventive measure recommended by BioVenic. Although vaccination with CAV-2 only prevents disease progression, it does not prevent infection with CAV-1 and CAV-2.
• Additionally, regular disinfection of surfaces, isolation of infected dogs, and minimizing contact between susceptible and infected individuals are important preventive steps.

BioVenic acknowledges the importance of addressing CAV infection and is dedicated to advancing the field through the development of diagnostic tools, vaccines, and treatment options. Our commitment to research and development is centered on elevating the precision and effectiveness of diagnostic methods, innovating vaccines, and enhancing therapeutic approaches. If you are interested in collaborating with us, please feel free to contact us.

References

1. Bru, Thierry, Sara Salinas, and Eric J. Kremer. "An update on canine adenovirus type 2 and its vectors." Viruses 15.5 (2010).
2. Image retrieved from Figure 2 "Different steps of CAV-2 axonal transport." Bru, Thierry, et al., 2010, used under [CC BY 4.0], the image title was changed to "Distinct stages of axonal transport in CAV-2."